Restoring All 90 Teeth on a Two-Stroke Engine Flywheel

Being well known for our repair capabilities, we repair damaged two- and four-stroke engine flywheels frequently. In most cases, a few of the flywheel’s teeth are damaged and we quickly restore these by installing a tailor-made repair insert. We usually do this in-situ, either during a port stay or during a docking.

The situation found on an European-owned 2’300 TEU box ship in September 2022 was very different. When the customer contacted us about a damage to the flywheel, we sent our colleagues from QuantiServ Singapore on board for an inspection.

Badly damaged flywheel

During the inspection it very quickly became clear that this was no ordinary case, as all ninety teeth were found severely damaged. An in-situ repair of 90 teeth would take too long and would not be cost-efficient either. As the ship was about to be docked very soon, we suggested to the customer to carry out the repair during the upcoming docking in southern China.

The colleagues from QuantiServ China took over the case. They worked out a very attractive proposal that was immediately accepted by the customer. Our engineers and technicians then started all preparation and planning.

Once the vessel was in the yard, the yard workers uncoupled the intermediate shaft, took the 3.5 ton flywheel off the engine and moved it out of the engine room through a narrow slot that they had cut into the vessel’s hull. The flywheel was then trucked to Shanghai, where the highly-skilled engineers and technicians from QuantiServ China immediately commenced to machine it.

They machined off its toothed rim and then shrunk on a tailor-made ring of forged steel onto the ø 3.2 meter flywheel. And to make sure that the ring stays put for the lifetime of the ship, they also installed a total of 135 large bolts. Once this was completed, new teeth were milled.

Milling new teeth obviously took time, owing to the large size of the flywheel. In fact it took five days and five nights of continuous milling!

After completing a few more processing steps, our Shanghai colleagues sent the flywheel back to the shipyard and to a very happy customer. The shipyard workers then completed this repair assignment, by reinstalling the flywheel to the 72-bore engine and by re-coupling it to the ship’s intermediate shaft.

Severely damaged flywheel prior to repair
Severely damaged flywheel prior to repair
Milling of new teeth
Milling of new teeth
Ready to be delivered back to the shipyard
Ready to be delivered back to the shipyard
Machining on a large vertical lathe
Machining on a large vertical lathe
The newly milled teeth
The newly milled teeth
During re-installation on board
During re-installation on board


The repair of every single tooth on a flywheel as presented above is not something that we do every day. Typically, just a handful of consecutive teeth are damaged. Follow one of the links below to see how we repair these cases in-situ.

Flywheel In-situ Repair on the US East Coast

Another successful flywheel repair assignment completed, in Florida, USA

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Flywheel Teeth Dentistry in Hong Kong

In-situ repair of a large 96-bore engine flywheel at Hong Kong anchorage

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In-situ Flywheel Repair in Mombasa, Kenya

In-situ Flywheel Repair on a 3’400 TEU Container Vessel in Mombasa, Kenya

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Metal Stitching an Engine Block from 1921 in-situ!

1921 Duesenberg Model A

We do a lot of in-situ work. We routinely carry out machining and metal stitching work, among others, on components that are too large to be moved to a workshop or where dismantling work is too time consuming or costly. But repairing a an antique car engine block, in the chassis, in a museum, is still quite special. Even for us.

The engine in question is an in-line, eight cylinder one with a bore of 72 mm and a stroke of 125 mm (2.875″ x 5″). With a swept volume of 4’256 cc, or 260 cubic inches, this early Duesenberg Model A engine is capable of producing up to 88 hp (66 kW) of power.

Repair in progress. The engine remained in the chassis, only the cylinder head was removed.
Repair in progress. The engine remained in the chassis, only the cylinder head was removed.

We got the opportunity to work on this engine as cracks had began to show at the corners of the engine block. The cracks originated from the threaded bores housing the cylinder head studs. They extended towards the outside of the engine block on one side and into the cooling water passage on the other.

The fact that the engine was left inside the chassis made the repair a little more challenging than usual. Our metal stitching expert had to use a mirror for much of the repair work. Without it he could not see, let alone repair the cracks at the rear end of the engine block. In addition to sealing the cracks with stitching pins, our expert also installed Full Torque™ thread inserts at the threaded bores. Unlike conventional thread repair inserts, Full Torque™ inserts do not create spreading forces. They are therefore the perfect solution for cases like this one, where threaded bores close to an edge have to be repaired.

Cracks extending from the cylinder head stud bores to the outside and to the cooling water space
Cracks extending from the cylinder head stud bores to the outside and to the cooling water space
Installation of Castmaster stitching pins.
Installation of Castmaster stitching pins. They are the strongest and most advanced stitching pins on the market today.
Ultrasonic inspection of the casting
Ultrasonic inspection of the casting to determine the wall thickness
Metal stitching in progress. Due to the location of the crack a mirror was used.
Metal stitching in progress. Due to the location of the crack a mirror was used.
The completed repair. Cracks stitched and Full Torque thread inserts installed.
The completed repair. Cracks stitched and Full Torque thread inserts installed.


Metal Stitching

Metal stitching is a very well-established repair method. It is applicable to a wide variety of materials such as cast iron, cast steel and many non-ferrous metals.

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Thread Repair

The repair inserts that we use to repair damaged threads are super strong and do not create spreading forces. They are ideal for high-load applications.

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Metal Stitching a Fractured Engine Block from 1913

Pierce Arrow

This post describes the repair of a Pierce Arrow engine block from 1913. The Pierce Arrow was the largest production automotive engine at its time. The swept volume of this 6-cylinder, 48 hp (36 kW), engine amounts to a whopping 13’500 cc (824 cu in)!

This engine is of the T-head engine type, which is essentially an early form of crossflow engine. This design is characterized by two separate camshafts, one on either side of the cylinder. One camshaft operates the inlet valves and the other the exhaust valves. This makes this engine design quite complex and expensive to produce.

The main advantage of the T-head engine design is the fact that it is not at all prone to knocking – a condition where the gasoline vapour in the cylinder ignites too early by itself due to compression, before it is lit by the spark plug. Knocking was a big issue especially during the early decades of the 20th century, when gasoline sold typically had a very low Octane rating. T-head engines were therefore popular until about 1920, when better fuel became widely available. At that time, the disadvantages of the design started to outweigh the advantages.

A large piece had broken off the cast iron engine block and had to be reattached
A large piece had broken off the cast iron engine block and had to be reattached

The in-line 6-cylinder Pierce Arrow cast iron engine block that we received for repair at our workshop at Lock-N-Stitch in California, USA, was severely damaged. A large piece of the casting had been broken off at the block’s front (timing belt) end.

Our metal stitching specialists successfully reattached it. In order to do so, they installed about thirty Castmaster™ stitching pins over a total fracture length of 160 mm, in material with a thickness ranging from 12 – 16 mm. For additional strength, they also installed two high-strength locks perpendicular to the fracture line.

The fracture line passed through a hole for a positioning dowel pin. To repair that, our specialists first closed the hole by installing a solid Full Torque™ plug, before drilling it anew in the exact location.

Badly fractured engine block
The completed repair.
The completed repair.
Close-up of the fracture line
Close-up of the fracture line
Repair completed. Stitching pins, locks and Full Torque insert installed
Repair completed. Stitching pins, locks and Full Torque insert installed

Dynamometer Roller Machining in a Swedish Car Factory

Our in-situ specialists from Gothenburg, Sweden, carried out an in-situ machining assignment in a Swedish car factory.

The four rollers of an end of line (EOL) dynamometer had to be machined. Their surface had been found worn and the customer therefore asked us to undersize them by 1.0 mm, so that they could be plated again by thermal arc spraying.

Dynamometer rollers look deceptively small as only a small part of them is visible. They in fact each have a diameter of 1’500 mm and they are 900 mm wide.

Our specialists used one of our NC-controlled, mobile milling machines fitted with a lathe cutting tool for the task. This arrangement worked very well and led to a great result.

Repairing a V12 Flathead Engine Block from 1934

Packard Twelve

We routinely work on museum pieces. In this post we introduce a typical case: The repair of a Packard Twelve engine block from 1934, carried out by our colleagues from Lock-N-Stitch in California.

As the name implies, the Packard Twelve is a 12-cylinder engine. It is a flathead engine, sometimes also called side-valve engine, where the intake and exhaust valves are contained within the engine block rather than within the cylinder heads. Flathead engines were very popular until the 1950s and were built in large numbers by automotive manufacturers. Their advantage is their simplicity, compactness, reliability and low cost as the flathead design obviates a complicated valve train. Such engines therefore need far less components than alternative designs such as, for example, single or double overhead camshaft arrangements.

The main disadvantage of the flathead engine is its relatively low efficiency and power output. The Packard Twelve V12 engine has a displacement of 7300 cc (445 cu in) and a maximum output of 119 kW (160 hp).

Engine block received with cracks in both longitudinal side walls and around the valve seats
Engine block received with cracks in both longitudinal side walls and around the valve seats
Repair finished
Repair finished. We stitched about 200 mm (8 inches) of cracks in this engine block.

Repair of cracks in the side walls of the engine block

When the engine block was delivered to us, it contained eleven cracks of various lengths. Some were small, others rather long. Added together, they amounted to a total length of 200 mm. In addition, the block suffered from corrosion and material loss around the camshaft spaces.

The cast iron block had been “repaired” before by arc welding. This has not been a great success – new, fairly large cracks could be seen extending to the left and right of the weld.

As they always so on cast iron parts on which someone has already been attempting a repair by welding, our specialists cut out all material in the vicinity of the weld, in the so-called heat affected zone. This is our standard operating procedure. Whenever cast iron is welded at, the heat from welding burns out the carbon, which constitutes between 2% and 4% of the cast iron. Once the carbon is burnt, the cast iron becomes hard and brittle, looses its structural integrity and becomes worthless.

To replace the cut out material on both longitudinal sides of the block, our specialists installed repair patches made of cast iron. They stitched them firmly in place with Castmaster™ stitching pins. Similar pins of various lengths and diameters were also used to repair the cracks found in various locations on the block, in material ranging from 3 – 10 mm thick. Some of these cracks are visible in the pictures below.

Our specialists also installed five Full Torque™ thread inserts to repair thread holes damaged by corrosion and erosion.

The engine block had been arc welded in the past. As expected, this did not solve the problem but led to further cracks extending left and right.
The engine block has been arc welded in the past. As expected, this did not solve the problem but led to further cracks extending to the left and right of the weld.
Crack extending leftward from the weld, serious corrosion at the edge of the sealing surface.
Crack extending leftward from the weld, serious corrosion at the edge of the sealing surface.
We removed the material that has previously been welded and installed a repair patch.
We removed the material that has previously been welded and installed a repair patch.
Crack extending rightward from the weld. Again, serious corrosion at the sealing surface.
Crack extending rightward from the weld. Again, serious corrosion at the camshaft cover sealing surface.
Installation of stitching pins to seal the crack
Installation of stitching pins to seal the crack
Skimming of cylinder head landing surfaces
Skimming of cylinder head landing surfaces
Left longitudinal side wall completed
Left longitudinal side wall completed
Right longitudinal side wall completed
Right longitudinal side wall completed

Repair of cracks around the valve pockets

A thorough magnetic particle inspection (MPI) of the block revealed hairline cracks between some of the valve seat and cylinder liner bores. We permanently repaired these cracks by installing small size stitching pins.

After completion of the repair, we took the opportunity to skim all cylinder head gasket mating surfaces, on the engine block as well as on the two cylinder heads.

Crack between valve seat and cylinder bore clearly visible during Magnetic Particle Inspection (MPI)
Crack between valve seat and cylinder bore clearly visible during Magnetic Particle Inspection (MPI)
Cracks between valve seat and cylinder bores successfully repaired
Cracks between valve seat and cylinder bores successfully repaired
Another crack
Another crack, seen here under Ultraviolet (UV) light during MPI

Metal Stitching and Line Boring on a Japanese Auxiliary Engine Block

In late 2021, a Greek owner of a 4250 TEU container vessel approached us for the repair of an auxiliary engine. The 26-bore, japanese-made engine had suffered from a so-called “side kick” – the connecting rod had smashed a hole in the engine block, above cylinder #2.

As the vessel was about to call Singapore, QuantiServ Singapore arranged for one of its metal stitching specialists to go on board to conduct a comprehensive damage assessment.

As is nowadays almost always the case, our specialist deemed the engine block damage to be repairable. We engineered a repair proposal, consisting of metal stitching and in-situ machining to be carried out in our workshop in Singapore. The customer gladly accepted our repair proposal due to the obvious time and cost savings compared to replacing the engine block. He made arrangements for the 12-year old engine block to be sent to our Singapore workshop for repair.

The block arrived at our workshop in March 2022 and was immediately attended to. The repair work carried out included the following main steps:

  • We arranged for a tailor-made cast iron repair patch to be cast in a certified partner foundry. The repair patch was then stitched in place using Castmaster™ stitching pins and matching locks. This provides for a permanent, very strong repair.
  • As the damage extended into the lower cylinder liner bore, a repair sleeve was installed there. The repair sleeve guarantees a good fit with the cylinder liner o-rings, preventing water leaks.
  • The ovality of seven out of nine main bearing pockets was found to be excessive. This finding was independent of the accident but needed attention too. We corrected the ovality with in-situ line boring.
  • All eight cylinder liner landing surfaces in the engine block were machined to clear them from corrosion and cavitation damage.

A Magnetic Particle Inspection (MPI) was carried out on the completed repair to the satisfaction of the customer and attending class surveyor.

From start to finish, the repair work took approximately four weeks to complete, well in time for the engine block to be sent back to the vessel during her next routine call to Singapore.

Engine block damage at cylinder number 2
Damaged engine block
Installation of stitching pins
Installation of stitching pins
Machining of the cylinder liner landing surface
Machining of the cylinder liner landing surface
Engine block debris
Engine block debris
Repair patch installed
Repair patch installed
Cylinder liner landing surface after machining
Cylinder liner landing surface after machining
Newly casted repair patch
Newly casted repair patch
MPI inspection after stitching
MPI inspection after stitching
Another job well done
After completion. Another repair job well done!

Metal Stitching on Historic Bridge in Washington DC, United States

Our American colleagues have just completed metal stitching repairs on a historic bridge crossing the Chesapeake and Ohio Canal.

The Canal

The Chesapeake and Ohio Canal stretches over a distance of 297 km (184.5 miles) from Cumberland, Maryland, to Georgetown, DC on the US East Coast. It was constructed between 1828 and 1850 by approximately 35’000 labourers, mostly immigrants from Europe. Its purpose was to enable the shipment of coal from the rural but coal rich Allegheny Mountains to the much more densely populated regions and sea ports along the Atlantic coast.

The canal was operated from 1831 until 1924. While originally built for the transportation of coal, it quickly became an important lifeline for communities along its way.

The bridge we assisted restoring. Visible in the foreground is one of the canal's 74 lifting locks
The bridge we assisted restoring. Visible in the foreground is one of the canal's 74 lifting locks

Boats were used to ship agricultural produce and lumber to markets downstreams. They then returned loaded with manufactured goods. These boats typically did not have their own means of propulsion, but were pulled along by mules walking on towpaths located at either side of the canal.

One end of the canal, Cumberland, lies at an altitude 184 m (605 feet) higher than the other end, Georgetown.  This meant that lift locks were needed – in total 74 of them were constructed. One of them is visible in the picture above, in front of the bridge.

In addition to the 74 locks, the canal also featured many other feats of early engineering. There were seven dams, about 240 culverts, a few aqueducts, a tunnel 950 meters (3’120 feet) long and, of course, bridges. A few of these bridges still exist today, such as the one that our metal stitching specialists proudly helped to restore.

Metal Stitching Work Performed

Exposure to the elements for over 150 years took its toll on the bridge structure. Cracks had developed in many of the vertical cast iron columns carrying the bridge deck. In all likelyhood, the cracks that were found were freeze cracks. Freezing temperatures are common in Georgetown from the middle of December until early March. If water enters one of the exposed, hollow columns and gets trapped there, then it very likely freezes during a cold winter night. Over time, the freeze/thaw cycles led to cracks.

All of the cracks ran in vertical direction. They had a cumulative lenght of 7’400 mm (25 feet). Our specialists sealed them with stitching pins and added perpendicular locks for extra strength. They then ground the locks and pins flush and made them blend in well with the weathered surface texture of the antique columns.

For the work to be carried out, a section of the canal had to be drained
For the work to be carried out, a section of the canal had to be drained
The width of the cracks required pins with a large diameter to length ratio
The width of the cracks required pins with a large diameter to length ratio
Installation of stitching pins
Installation of stitching pins: Close to 1'000 were used for this project
In many locations, the cracks were wide open
On some of the columns, the cracks had caused a gap of up to 12 mm
Our specialists stitched over 7 meters of cracks
On this restoration project, our specialists stitched over 7.4 meters (25 feet) of cracks
Once completed, the repair blends in very well
The completed repair blends in very well
Stitching in progress
Metal stitching in progress: Stitching pins installed in an overlapping pattern
Locks were added for extra strength
Metal stitching in progress: Adding of locks, perpendicularly to the crack, for extra strength

Nuclear Power Plant Emergency Diesel Generator Block Repair

The operational requirements for emergency diesel generators (EDG) installed in nuclear power plant are very strict and demanding. In case of an emergency event leading to the loss of off-site power, a nuclear power plant’s EDGs are meant to supply independent, redundant power. From this follows that they have to start reliably and quickly  under any condition and must be able to take on load almost instantaneously, which generally means within about 10 Seconds. This is tested regularly under real-life conditions, according to the prevailing nuclear codes, standards and regulations.

This testing regimen of sudden load changes puts an enourmous thermal loading on most of the EDG’s internal components and on its auxiliary systems. Excessive wear and tear is therefore to be expected and is indeed a small price to pay for ensuring plant safety.

For years, QuantiServ has been supporting nuclear power plant operators and contractors serving them with specialist services throughout the long service life of the plants. We are happy to play a small, but nevertheless important role in ensuring safe and reliable electricity supply from whatever source.

The enclosed pictures show the machining of an impressively large, 20-cylinder engine with a rated output of 4000 kw, a cylinder bore of 240 mm and a stroke of 230 mm. It suffered from a small internal defect, caused by wear and tear, that we successfully remedied in our workshop in The Netherlands in 2020.

15 Years Service Experience With Metal Stitched 2-S Engine Columns

In October 2020, kindly acting upon our request, the crew of a 53’000 DWT bulk carrier checked the condition of the guide rails on their main engine. Specifically, they checked whether a metal stitching repair that was done in 2005 is still in good condition. Besides a periodical visual inspection, the crew carried out liquid penetrant testing (PT) to check for the presence of cracks.

The inspection revealed that the repair is still in perfect condition. No abnormalities such as cracks or loose stitching components were found.

At the time of writing, this engine had accumulated over 77’000 running hours / 15 years in service since the said metal stitching repair was carried out in October 2005 in Kure, Japan.

Location of the 660 mm long crack that was repaired in 2005
Location of the 660 mm long crack in the gear column, repaired in October 2005

At that time, the engine had 27’000 hours on the counter. Meanwhile, until October 2020, the engine has accumulated 103’000 running hours,  77’000 of them were with repaired guide rails.

To the best of our knowledge, this makes this engine the longest-running one with structural repair to the columns (A-frame) or bedplate carried out by metal stitching.

The permanent repair done in 2006 involved the installation of stitching pins and locks from Lock-N-Stitch to repair a 660 mm long crack. The crack was located in a 13 mm thick steel plate in the gear column of the 6-cylinder, 48-bore two-stroke engine.

The vessel remains in service and we continue to monitor it. Not because we have even the slightest doubt about the quality or durability of the repair, but because she is a living testament to the permanence of our metal stitching repairs.

Area repaired at the side of the intermediate gear wheel boss
Area repaired at the side of the intermediate gear wheel boss
The general area where the crack was repaired
The general area where the crack was repaired
Close up of the repaired area
A close-up view of the repaired area
After application of dye penetrant
Non-destructive examination: Application of dye penetrant
Red dye cleaned, developer about to be applied
Non-destructive examination: Dye penetrant removed
Developer applied - no defects visible
Non-destructive examination: Developer applied
Non-destructive examination: Outline of locks and stitching pins just barely visible
Non-destructive examination: Outline of locks and stitching pins just barely visible

Metal Stitching Repair of Two-stroke Engine Bedplates

This post introduces metal stitching as an attractive solution to repair cracks in two-stroke engine bed plates.


The term “metal stiching” is most commonly associated with the repair of cast iron parts, as an alternative to welding, to which cast iron does not lend itself easily. Due to its brittle nature, cast iron tends to fail again rapidly after welding, unless the welding takes place at very elevated and uniform temperatures. These conditions are hard, if not impossible, to achieve in most workshops, let alone at site.

It is less commonly known that metal stitching is also an increasingly often used process for the repair of steel parts, where welding actually would be possible. There are good reasons for chosing stitching over welding, even in steel.

First and foremost, metal stitching is a cold process and thus does not lead to deformation or latent heat-induced stresses in the part being repaired. Post-repair (in-situ) machining to correct these deformations is therefore rarely required.

Second, as we have shown through independent labaratory testing, a metal stitched junction that has been made by a qualified operator using Lock-N-Stitch tools and stitching components, exhibits a tensile and fatigue strength that is equal to, or better, than that of a welded junction.

During the last few years, QuantiServ have gained extensive experience in applying the metal stitching process to crack repairs in two-stroke engine bedplates and columns. Two instructive cases are discussed below, both involving container ships with 96-bore engines.

On the first vessel, the stitching was carried out in stages, during successive port stays. On the second, the repair was carried out during a regularly scheduled dry docking in China.

Case 1: Bed Plate Metal Stitching During Successive Port Stays

In the course of a crank case inspection, a 800 mm long crack was found in the main engine bedplate on board a 15,500 TEU container vessel in 2019. Contacted by the ship owner, we carried out an assessment. It revealed that the crack would propagate quickly if the engine, a 14-cylinder, 96-bore one, would continue to operate at, or near, its nominal speed.

We proposed to the customer to carry out the repair while the ship remained in service. As the thirteen year old vessel was engaged in a “high-rate/less-time” trade, the customer of course jumped at the opportunity to get the crack repaired without any vessel off-hire. Following a review of the vessel’s trading pattern, we decided to carry out the repair during successive port stays during the vessel’s Northern European loop.

Our specialists commenced their work as soon as the vessel was alongside in port and did not stop anymore until the engine had to be restarted. They then rested during the short voyage to the next port, where they continued in the same manner.

While working, our specialists discovered that the crack in fact was about 300 mm longer than had previously been reported by the crew. This meant that the time in Europe was insufficient to repair the crack in its entirety.

Our specialists revisited the vessel a few months later, again in Europe, to repair the previously unreported section of the crack. All in all, it took seven port stays of a few hours each to repair the bedplate.

Attendance Voyage Number of port stays
First Antwerp – London 4
Second Bremerhaven – Antwerp 3

In total, we repaired on this bed plate over 800 mm of crack in steel plates with thickness ranging from 18 – 50 mm, without a single day of off-hire or otherwise interfering into the vessel schedule.

To repair this bed plate, metal stitching was chosen over welding because it has the following advantages:

  • The vessel stayed in operation throughout the repair. The stitching was done in stages during port stays, a few centimeters at a time. With welding, this would not have been possible. The vessel would have had to be taken out of operation for around three weeks.
  • Lower costs, compared to welding. A competitor proposed to carry out repair by welding in 20 days. We repaired it by stitching in 12 days. Less time spent means less costs.
  • For metal stitching, a hot work permit is not normally required. Such a permit would be very difficult to get in container terminals, meaning that welding would not have been possible from a safety point of view.
Crack runs from the girder side plate down into the oil sump
The crack runs from girder side plate down into the oil sump
Metal stitching repair in progress
Crack without the sealing compound that was temporarily applied
View of the crack without the sealing compound that was temporarily applied
The completed repair, prior to cleaning and painting
The completed repair, prior to cleaning and painting

Case 2: Bedplate Stitching During Dry Docking

The second case discussed here concerns an 8-year old, 13,000 TEU container vessel with a 12-cylinder, 96-bore main engine. The crack discovered on this engine was quite similar to the one described above.

Since the crack was discovered shortly before the vessel was scheduled to undergo a routine dry docking, it was decided to repair it during the docking period in China in 2020.

The crack extended over a length of 750 mm in steel plates with thickness ranging from 18 – 50 mm. Repairing it took our specialists eight days, working in single shifts.

Crack runs from girder side plate down to oil sump
The crack runs from the girder side plate down into the oil sump
Stitching of the crack in progress
Metal stitching of the crack in progress
The completed repair prior to repainting
The completed repair prior to repainting

The first two-stroke diesel engine that we have metal stitched has meanwhile accumulated 77,000 hours. We repaired a 600 mm long crack in the gear column (A-frame), in 2006. The repair is still in perfect condition today.

04 January 2021

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The two repairs presented above were carried out using stitching components from the American company Lock-N-Stitch. We would like to stress that we have labaratory-tested other products available in the market and that we have found their strength to be insufficient for demanding applications like these.

Read more about metal stitching

Four-stroke Engine Block Metal Stitching and Crankshaft Machining

Over the years, medium-speed diesel engines have become very popular for a variety of applications, most notably in ship propulsion and in power generation. Accordingly, the number of such engines in service is very large.

Due to their large number and to the relatively high nominal speeds, combined with significant mass inertias, one would from a theoretical stand point expect more fequent and more severe damages on medium-speed, four-stroke diesel engines than on low-speed, two-stroke ones. That this is indeed the case in practice is evidenced be the fact that we are frequently contacted and subsequently repair a few dozen cases of severe engine damage every year.

Here is a typical example, one of many:

A Korean-made auxilliary engine with eight cylinders, 210 mm bore and 320 mm stroke suffered a serious bearing failure on crankpin #1. The engine block and crankshaft both got severely damaged, due to the connecting rod impacting both. The accident happened while the vessel, a Ro-Ro ship, was trading in East Africa.

Her next port of call was in Florida, United States, where our technicians went on board for a thorough inspection. They determined that both the crankshaft and engine block were repairable. As in addition to crankpin #1, which was badly damaged, all other pins were found with corrosion and scratch marks, we suggeted to the customer to offload the engine and to sail a few weeks without it. The customer agreed.

The engine was offloaded in Freeport, Texas, for repair and was delivered back to the vessel 46 days later in the same port. In the meantime, the vessel continued to sail with one engine less. The duration of the voyage, 46 days, was more than sufficient for our specialists to repair the crankshaft and engine block according to our very exacting standards.

Repair of the crankshaft

Due to the damage sustained by the accident, crankpin #1 had to be machined to – 3.00 mm. This was necessary to clear all dent marks. And as the other seven crankpins were suffering from scratches and/or corrosion, it was decided to machine them all to – 0.50 mm.

Repair of the engine block

Repair of engine block before and after

The cavity in the block caused by the accident was fairly substantial. A total volume of about 6’000 cm³ (366 in³) of material was missing and cast iron plates with a thickness of 19 – 51 mm (0.75 – 2 in) had to be repaired.

Our cast iron repair specialists scanned the damage with a 3D scanner. The data thus acquired was then used to fabricate a perfectly-fitting cast iron repair patch. The repair patch was stitched in place with stitching components, chiefly Castmaster stitching pins and locks, that are sold by Lock-N-Stitch.

After the repair was completed, it was hardly visible and the customer was very pleased with the outcome.

Here is a step-by-step description of how the block repair work was carried out:


Cooling Water System Reverse Engineering

After 25 years of intermittent operation and of being exposed to the elements, the cooling water radiators of an 3500 kW emergency diesel generator installed in a thermal power plant in Macau had degraded considerably. Thus, the power plant owner decided to replace them.
Unfortunately, the original documentation and specification were not available anymore. Therefore, QuantiServ reverse engineered them and got 12 new elements made by a specialized manufacturer.
The new radiators have just been installed and commissioned and will provide reliable cooling for many years to come.
Although this was a small case, it illustrates the important advantages that reverse engineering provides. Many of the industrial plants that we maintain and repair on behalf of our customers have a lifetime of many decades. But that does not mean that the documentation always survives that long, or that spare parts are still available. And sometimes even the OEM himself, or his sub-supplier, may not exist anymore.
It is thus comforting to know that QuantiServ has the skills, tools and experience to reverse engineer and reproduce all kinds of machinery components, even very complex ones and entire systems.

QuantiServ Has Been Awarded “Manufactured Again” Certification

If you are a buyer or a procurement officer, then you probably already know about the economic advantages of reconditioning/remanufacturing. However, you might worry about the quality of the work performed and the durability of the reconditioned component. That is why the Remanufacturing Association (MERA) has developed a formal certification program.

Manufactured Again Certification

MERA’s Manufactured Again Certification Program promotes environmental stewardship. It does this by recognizing remanufacturing companies that meet the same quality standards as new manufacturing facilities.

QuantiServ is proud to have achieved certified status and to be a member of the program. The Manufactured Again certification gives our customers piece-of-mind and assurance that we are providing them with a quality product and thus enables them to make better buying decisions.

Read more about our technologically advanced yet economical reconditioning solutions by following the link below.

Reconditioning Solutions

Flywheel In-situ Repair on the US East Coast

Starting up a handymax bulk carrier’s 48-bore, two-stroke main engine with its turning gear engaged resulted in the turning gear shattered and in damage to 12 consecutive teeth on the flywheel.

The turning gear was damaged beyond repair and had to be replaced. Not only was its housing shattered but the planetary gears were completely destroyed too.

Faced with the costly and unpalatable reality of most likely having to replace the flywheel as well, the ship management company turned to QuantiServ for help. Always liking a challenge when we see one, we engineered and delivered a comprehensive solution that consisted of the following:

  • Inspection on board
  • CAD and FEA modeling to engineer an economical yet structurally very strong solution
  • CNC machining of repair inserts in our workshop
  • In-situ machining of the flywheel on board
  • Stitching the repair inserts in place

Our in-situ machining and metal stitching specialists carried out the work in February 2019, during the vessel’s port stay in Florida, without interfering in her schedule.

QuantiServ carries out a number of gearwheel repair assignments every year, mostly for industrial, marine and mining customers.

Jaw Crusher In-situ Machining, 700 Meters Underground

In November 2018, our in-situ specialists carried out machining work in one of the world’s most modern underground mines, located in central Sweden. The mine processes about 2.5 million tones of ore annually and produces gold, silver, zinc and lead.

The assignment lasted about a week and consisted of milling, drilling and tapping work on a large jaw crusher located at a depth of 700 meters. There, the ore is crushed before it is hoisted to the surface for further processing.

Our specialists machined the upper section of both the stationary and the moving jaw. On each jaw, they milled off about 26,000 cm3 of steel and then drilled and tapped them so that a newly fabricated section could be bolted on.

Brand New Light Surface Grinding Tools Now Available for Sale!

We are asked frequently, whether we are selling the in-situ machining tools that we have developed and manufactured and that our specialists use in the field. While such requests are of course flattering and while we appreciate that other companies find our tools appealing and would like to purchase them, we have up to today always politely declined such request. The reason is that we first and foremost see ourselves as a top-notch in-situ machining company and not as a tool manufacturer. Our tools are thus a means to end – the more accurate and efficient they are, the better the result of our machining assignment that our customer comes to enjoy.

Our very newest Light Surface Grinding machine (LSG) has now proven to be so popular, that we have decided to break with tradition and to make it available for sale.

The machine was designed to be as compact and portable as possible. It has an adjustable base, no heavy adapter plates are therefore necessary. Its total weight is 30 kg (66 lbs). This is significantly less than any comparable machine currently on the market and means that it does not have to be sent as cargo to a ship or power plant, but can be brought along as checked-in luggage.

The tool’s main purpose is to quickly and accurately skim the cylinder liner landing surfaces at the top of medium-speed engine blocks. It can be used to machine diameters of 360 – 670 mm, which makes it suitable for engines with a bore size of 260 – 500 mm. Additional accessories to also skim the landing surface on the cylinder liner are also available.

The advantages of the Light Surface Grinder (LSG) are many:

  • High accuracy
  • Fast to set up and easy to use
  • Compact design
  • No adapter plates are necessary as the machine’s base is continuously adjustable
  • A single machine covers the range from ⌀ 360 – 670 mm
  • Total weight = 30 kg (66 lbs)

Contact us for more information, or to order one.

Contact us



Four-stroke Cylinder Head Valve Seat Bore Repair

Our reconditioning centre in Vancouver has just carried out furnace brazing of 13 pieces of 32-bore four-stroke engine cylinder heads for Canada’s premier ferry operator.

The valve seat bores were seriously damaged by cavitation and corrosion. Machining to over-size was not possible anymore because this had already been done during past overhauls and the maximum diameter had already been reached.

QuantiServ’s unique process starts with the generous removal of any damaged material around the valve seat bores. Thereafter steel sleeves are soldered in in a vacuum oven before finishing off the heads by NC machining of the valve seat bores. Standard-size valve seats can then be installed, followed by pressure testing of each cylinder head.

QuantiServ’s furnace brazing process is applicable to four-stroke cylinder heads of any engine type with a cylinder bore diameter of > 200 mm. It is patented word-wide and classification approved (LR / ABS). Classification certificates are available on request.

Condition of the cylinder heads before reconditioning:


Condition of the cylinder heads after reconditioning, before installation of the valve seats:

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Flywheel Teeth Dentistry on a Container Ship in Hong Kong


Our in-situ specialists from QuantiServ Dubai have just completed another flywheel repair. This time it was for a very large European owner, on one of their large container ships with a 12-cylinder, 96-bore engine while on anchorage in Hong Kong. Our specialists machined off two damaged teeth and installed an insert, which they had pre-fabricated at their workshop before boarding the vessel and which they sent on board jointly with the in-situ tools.
The total work took 42 hours – three long days of work – and the result is something that they can be very proud of!

Damaged flywheel with two severely damaged teeth

Damaged flywheel with two severely damaged teeth

Removal of the damaged teeth by in-situ milling

Removal of the damaged teeth by in-situ milling

Pre-fabricated insert installed, repair completed

Pre-fabricated insert installed, repair completed

ABC Engineering Pte. Ltd. in Singapore joins QuantiServ

abc-logoWe are very honoured and happy to announce that all personnel from ABC Engineering Pte. Ltd. have decided to join QuantiServ with effect from 1 April 2017. This combination of forces further extends QuantiServ’s offering and geographical reach, particularly in Indonesia.

ABC Engineering is a well known company with excellent reputation that has been providing in-situ crankshaft and engine block repair services to customers in Southeast Asia since the 1970s.

The personnel from ABC Engineering and QuantiServ look forward to continue to serve ABC Engineering’s customers as reliably and to the same exacting standards as they always have.

QuantiServ Singapore’s own wharf again able to accommodate vessels

Maintenance dredging at our own wharf in Singapore has just been completed. We are now again able to accommodate vessels of up to 110 meter length and 5.0 meter draft for repair, right next to our very well equipped 10,000 square meter workshop. It does not get any more convenient and economical than this!

Our very own wharf in Singapore, right next to our workshop.

Our newly dredged, very own wharf in Singapore, right next to our workshop.


In-situ machining of lateral surfaces on 20V32 engine block in Bangladesh

Lateral surfaces before and after in-situ machining

Lateral surfaces before and after in-situ machining

In-situ machining of lateral surfaces on a 20V32 engine block in a power plant in Bangladesh

In October 2016, QuantiServ received an urgent request to carry out in-situ machining on a 20-cylinder 32-bore engine block in a power plant in Bangladesh. During the replacement of the crankshaft it was noticed that both lateral surfaces of main bearing cap number 5 showed signs of severe fretting and were in need of machining.

Immediately, in-situ machining equipment was prepared at QuantiServ’s Dubai workshop and was sent to site. Once the equipment had arrived at site, QuantiServ’s engineers from Dubai performed in-situ machining on the engine block to achieve a clean surface that was free from damage. The in-situ machining process was constantly monitored by laser to ensure perfect alignment and adherence to very tight machining tolerances.

The main bearing cap was sent to a local workshop in Bangladesh for machining and installation of compensation plates. This process was supervised by QuantiServ’s engineers. Once the machining was completed, all mating surfaces for the main bearing cap were checked with marker blue to ensure a perfect fit.

Once the work was completed, a final check by laser on the assembled bearing cap showed that both the bore alignment and diameter fully conformed to the engine maker’s specification.

No Job Too Small – If it Solves the Customer’s Problem

No job too small – if is solves the customer’s problem

A ship’s crew received a new cylinder liner in a mid-eastern port. Unfortunately, while lifting it onto the vessel, a sling came lose and the liner crashed hard on to the deck. Luckily no one was injured, but it caused a piece of cast iron at the circumference to be chipped off, rendering the liner unusable.

Instead of scrapping the liner, the Superintendent contacted QuantiServ and sent us pictures. After we confirmed that we could salvage the liner, he shipped it to our workshop in the Netherlands.


There our skilled machinists milled off a section of the liner and confirmed that there were no further cracks in the material. They then produced on a CNC milling machine a new piece that perfectly resembled the size and shape of the missing material. This they locked in place with glue and screws, thus saving a liner that otherwise would had to be scrapped.