Triumph TR6 Thrust Washer Explained

If you have performed an engine crankshaft end float check and found the measurement to be beyond the allowable limits according to your workshop manual, then you need to stop driving your car immediately and determine the cause of the problem. In most cases, this would be caused by excessive crankshaft thrust washer wear, which is usually attributed to too many miles for this little bearing that has a big job to perform.

Thrust washers (especially in a Triumph six-cylinder engine) are regular maintenance check items that need to be replaced once in a while because of normal wear. If the end float is beyond the allowable limit, and you are using an OEM steel thrust washer, then it may have already worn through the thin copper/nickel plating to bare steel, which means the wear will begin to increase dramatically. If this wear continues, it will eventually damage the engine block. To inspect your thrust washers, you will need to drain the crankcase oil, remove the engine oil pan and main bearing end cap near the flywheel, and inspect for excessive wear or possible damage.

If during your inspection you discover the thrust washer has dropped to the bottom of the oil pan, then there's a good chance there may be damage to the side of the bearing end cap. Fortunately, in many cases the crank shaft surface may be worn, but it may be polished from the abrasive wear. If this is the case, and the damage is minimal, then you may be able to install a solid alloy type to replace the original syle steel thrust washer. The alternative is pulling the engine, repairing the damage, and replacing parts.

Premature thrust washer wear can be attributed to several things. Whenever there is friction, there is wear. This is why the thrust washer needs to be replaced at regular intervals. There are some ways you can help extend the life of the thrust washer.

1) An improper clutch pedal adjustment can cause a constant load on the thrust washer.

2) Driver "riding" the clutch. This is when the driver of the car rests his or her left foot on the clutch pedal while driving.

3) Holding the clutch pedal to the floor while waiting at a stop light or for a train to pass.

4) Pressing the clutch pedal to the floor and holding it there while starting the car. When an engine is started after a period of rest, gravity causes the oil to drain to the oil pan. When the engine is started again, it takes a period of time for the engine oil to get distributed to this area again. Just a few seconds with lack of lubrication will cause wear. It is best to place the car in neutral and leave your foot off the clutch before starting the car.

Another potential cause of rapid wear is re-installing the thrust washer backwards. This is especially bad when using an OEM steel thrust washer because the backside is bare steel and has no lube grooves. If the lube grooves are facing away from the crankshaft mating surface, both steel surfaces will wear very rapidly.

Why does the Triumph six-cylinder engine crankshaft thrust washer encounter wear, and what are the results?

The TR6 crankshaft thrust washer is small and has a very big job to do. The original (OEM) version is made of steel and has a very thin copper alloy plating on the bearing surface. The TR6 has a very heavy clutch spring, and when the operator presses the clutch pedal to the floor to change gears, there is a terrific force applied to the little thrust washer. It's amazing that it lasts as long as it does.

Once the thin, soft copper facing on the steel washer wears through to bare steel, it will begin to wear very rapidly against the spinning crankshaft surface. Eventually (rapidly), the thrust washer will wear enough to allow the thrust washer to fall out of place and end up at the bottom of the oil pan. Without the thrust washer in place, the crankshaft will now come in contact with the side of the bearing journal end cap. Not only does this generate abrasive particles for other parts of the engine, this wear will cause extensive damage to both the bearing journal and crankshaft.

The crankshaft will continue to wear into the end cap until it finally comes in contact with the engine block side of the main bearing journal. Once the crankshaft has worn far enough to damage the engine block, the entire engine will need to be pulled to determine whether it can be repaired.

If the problem is caught soon enough (before engine block damage), there is hope. The main bearing end cap face can possibly be repaired, and the crankshaft thrust face can be usable if anything other than some light wear. If the crankshaft thrust surface is lightly worn with a polished appearance, there's a good chance it can be salvaged also. Even though it may be slightly worn, the alloy thrust washer will conform to the slightly polished irregular surface and perform just fine.

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Please note: Do not use an original style (OEM) thrust washer if the crankshaft thrust surface is anything less than perfect. The increased friction will cause the thin bearing surface to wear through to bare steel, and extensive engine damage may be the result.