I was scheduled to bring my 924S in to do a timing belt job this morning as I suspect they hadn't been done in 10 years (I bought it in Nov, driven about 2000 km). I'm driving up and all of a sudden in 3rd gear the car just isn't accelerating as well as it should. Hm. Ok. Getting really worried but downshift, shift back up and it rolls along fine again. Then I start going up another hill right by my shop and it does it again. I pull in and turn off the engine and it turns off really oddly, like too fast. I looked in the inspection port on the belt cover and the belt looked a little looser than it did last time I checked.

Mechanic calls an hour later and says it won't start. Now I'm really worried.

I go in at the end of the day to see what's going on and he says he fired it up at a really low idle and got it in the garage. Then he took the cover off and said it looks like the "upper pulley" seized a bit but the belt was still on and just loose. He was still in the process of doing the job as he was replacing the motor mounts as well and the car will be done tomorrow. He says there is no damage and I got lucky.



But then I got home and I started worrying again. If that sort of thing happens would the valves make contact and bend? He is an experienced mechanic who has done the job a bunch of times on different 944s/924S's but I just wanna make sure his reasoning checks out as a lot of you guys are experts of the car, moreso than a lot of indy Porsche/foreign car guys. Should I get him to do a compression test?

Keep in mind my car just kept going and when I downshifted operated as normal and I heard no really odd sounds from the engine, just a bit of rumbling when I was in third going up a hill or two. I actually thought it was a fuel filter, not the belt!

 

you're probably ok.

a pulley going bad which led to that significant drop in power sounds highly plausible.

then neither you or your wrench mentioned anything that strongly suggest belt slip.

you'll know soon.

 

Hmm ok, that makes me feel a LOT more comfortable.

Probably the luckiest SOB on this forum lol. I doubt anyone has had the timing belt start to fail on the drive over for the scheduled belt change.

....Either that or the unluckiest SOB ever

I know what you're thinking... drop that engine and just put a V8 in there!

 

The rare time it actually happens...good timing! (Pun intended) did you take her to Kingston?

 

Larry in Brockville. Thank God I did or it would have died on the way to Kingston lol.

 

If you're really concerned, it wouldn't take much to do a quick compression check. Under the circumstances, and since it's still in the shop, it's worth a little extra to be sure.

 

A compression test should be about 1/2 hour of labor. Have it done. If your car is an '88, I'd expect the values to be about 165 psi. If it's an '87, about 10 or 15 psi less.

If a valve is bent, I expect it would be like 95 psi...

 

It's an 87 and I could have sworn my results were around 170 when I got a ppi done. I'll have to check if I have a record of it somewhere.

Either way yes I'll request one.

 

I wouldn't be surprised at 170 psi. It can vary due to how warm the engine is when it was done, or if the head has been shaved a little.

 

It's only got 50000 miles on the engine but driven regularly a little bit every year so it's still in fantastic shape. It would be a real shame to damage an original engine that's this great. Hopefully it's still just fine.

 

Got the car back today. Decided to talk to the mechanic first before bothering with a compression test. He said he doesn't see any reason as to why it shouldn't perform as expected, and he took it for a spin and it pulled great, better than most 924s/944s he's driven.

After taking it out for an hour I have to agree with him. The motor is pulling excellently. And what a HUGE difference replacing the motor mounts makes! Holy cow! I fell in love with the car all over again