Ever Break a timing belt this way?

[jbaeng]

sorry, here is the whole story...

I bought my '88 NA 944 in April '08 w/ 178,000 miles, first thing i did was replace belts and water pump! Nine months ago, I broke 200,000 miles driving it to the east coast when crossing over the Mississippi river. I knew it was a gamble driving it to NJ to work there for a while but figured i'd take the risk. it was quite dependable for the 9 months i've been here and will be going back to California in two days. when I hit 215,000 miles I needed to do a front seal replacement so i did belts and pump just for good measure. I checked my belt tension with a Kricket tool and the belt twist method I've used on FWD VWs for years and even had a shop check it after driving a few thousand miles with the official porsche tool! The car has 228,000 miles now and decided to ship it back instead of driving it cross country.

Now explain my disaster! i was driving in to work yesterday on an access road approaching two cars waiting at a stop sign to turn left onto the road i was traveling on. The first car took off and I let off the gas pedal (35 mph zone) to coast and give them more room to pass in front of me. All of a sudden, the second car, an asian women in a black SUV, took off right behind the first car right in my path. I went right for the brakes and before I could get the clutch pedal in, I locked up the wheels on the sanded road and stalled the engine. If there was any good news, I just missed this car and the lady looked at me as if I was nuts! I still was moving slightly so i tried to just let the clutch out and get the engine going and continue my drive back into work. the engine would not start and sounded different. i was fearing the worst but had my fingers crossed. i was amazed the car made it the 9 months and the car was still doing great and I just wanted to get it home back to the Santa Cruz area. I had it towed to a local shop familiar with 944's and we pulled the inspection plug on the cam pulley and cranked the engine and the distributor wasn't turning, apparently a broken timing belt. such a bummer...

i assume the sudden deceleration of the camshaft caused the belt to fail. perhaps this failure was immanent? I'm getting the non running car shipped back to my house next week and will do the repair as a project since i left my newer pilot at home that I will drive.

did this broken belt ever happen to anyone else like this or just during normal operation? a real achilles heal of this car from what i've read and heard. I was glad I brought it out here with me since it was a joy to drive and got numerous comments from people since I've done a lot to get it looking and running good. People have told me to just part it out, but they just don't understand! I had an '81 911SC for a while that i loved but the 44 has a very special personality.

sorry i typed so much hear but just had to put this on the board and get out my frustration! Next time I write here I will be back in CA that I've missed so much.

[mistertate]

I think that's a pretty common failure mode. The "stall" was when the belt broke.
'88 is the best 8V NA engine, if you can't afford to fix it then someone will probably be happy to have those pistons.

[Rasta Monsta]

Only 12,000 miles? I'm guessing when you get it apart you'll find the belt intact and something else broken under the timing cover.

[cwiert]

Originally Posted by mistertate

'88 is the best 8V NA engine.

Why???

[Endat]

Originally Posted by cwiert

Why???

probably because its the 2.7 and the 3.0 after it was 16v

[cwiert]

Originally Posted by Endat

probably because its the 2.7 and the 3.0 after it was 16v

'88 still has the 2.5. The 2.7 didn't come until 1989.
Sorry, I was just curious... I didn't mean to hijack the thread.

[cam100]

I'm sorry to hear about your belt failure -- I've been there myself. I can't see how that situation put any less pressure on the belt than any other quick acceleration- or deceleration -- which these engines are designed to handle. If it was really just the belt that broke, it must have been defective.

[Schumi]

The good news is that you have a strong clutch. Bad news is that the brakes locked up the rear wheels, locking up the driveline. The clutch held and the crank stopped spinning quicker than the camshaft could stop and thus snapped the belt.

Sound like the car is worth the repair though. Look into getting a rebuilt head from Bennington Motorsports he is a member here. Getting a rebuilt, ready to go head will save you a lot of downtime.

[carlege]

what timingbelts do you use? conitech?

[SolReaver]

Sorry about your luck there...what is the story of the rest of the TB components? Is it possible something else let go other than the belt? Did the inner teeth strip or what?

[jbaeng]

Hi all, the car will not be back here in CA until Wednesday next week. Then I'm off to Richland Washington for two weeks. Once I get back I'll tear it down and post the results of the post modem. I'll try to put some pics of what I find; here is one of the car this summer at Englishtown NNJR auto-x. Too nice to part out. I dropped by parts heaven and spoke to Al; I'll most likely buy some valves and get the head job done to get the top end overhauled. The rest of the car and engine seem to have a lot more life left. More to come in a few weeks.

[Born2bwild1191]

Originally Posted by Rasta Monsta

Only 12,000 miles? I'm guessing when you get it apart you'll find the belt intact and something else broken under the timing cover.

Maybe im missing something. He replaced the belt when it had 178k, right? and it had 228k when it broke? Thats 50k miles on a belt, when the recommended change is every 30k. Its possible i may have read it wrong, but it seems to me it may have just been an old belt. Plus, wouldn't pulling the ebrake without pushing the clutch in wheel you're moving do the same thing as locking up the back wheels with the regular brakes?




EDIT: Just re-read, didnt realize he replaced at 215k! yeah, that's odd.

[Rudeboy42]

Originally Posted by Schumi

The good news is that you have a strong clutch. Bad news is that the brakes locked up the rear wheels, locking up the driveline. The clutch held and the crank stopped spinning quicker than the camshaft could stop and thus snapped the belt.

Sound like the car is worth the repair though. Look into getting a rebuilt head from Bennington Motorsports he is a member here. Getting a rebuilt, ready to go head will save you a lot of downtime.

How much do those rebuilt heads usually cost?

[TSNAPCRACKLEPOP]

mine was near 400, but it was the wrong place to take it. i think some get them for around 250. Kansas city prices)

[Porschenut1066]

Hello,
I have had a few belts break and one reason for a short life is that the tube that sucks out the hot air from the Timing belt is broken off. This makes the belt heat up too much and allows it to fail prematurely. Just a thought.