Case Studies

Porsche 944 and 951 – Balance Shaft Alignment During Timing Belt Service

AMC Tech Tip – Porsche 924/944/951 Balance Shaft Alignment
We have a very nice 951 in the workshop today that came in with a very noticeable vibration. Engine mounts had been recently replaced at another shop, apparently in an attempt to correct this.

Tis The Season

Spring is the season for Porsche 924/944 timing belt calls and quotes, and invariably someone always needs one “redone” because all the parts were not replaced or replaced correctly.

Important – No Shortcuts

There is a huge temptation to do the “economy job” on these, but this is a false economy, and over the years, I’ve seen timing belts replaced with the old balance shaft belt and tensioners left. They rarely make it to the next service, which results in significant engine damage when they fail. Do it right the first time, and you won’t have to pay twice. 😉

Easy oversight on this job is to mistime the balance shafts, so the weights on the shafts, which are meant to cancel out the engine vibration, actually ADD to it. Not a good thing.

Service Tips
There is real science and trick to doing this correctly, and over the last 30 years, we’ve corrected many of these that have come out of other service facilities. I’ve even made a mistake a few times but caught it quickly.

The trick in these cars is to be sure that not just the timing belt is replaced; you’ll want to ensure the water pump (driven by the timing belt), rollers, and tensioners get attention. Also, a quick look at the camshaft, crank, and balance shaft seals will save you headaches in the long run.

Questions, we’re here for you and your car!

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If you have any questions, or need a copy of your service history, please do not hesitate to contact us directly. (207) 882-9969.

Thank you,
Bruce and the AMC Team

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