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BadMonkey's Avatar
 
Join Date: Apr 2005
Location: Miami, Florida
Posts: 20
what could have caused this???

1987 Turbo with 964 cams. I just finished a top end overhaul and things were great. I take it easy just because I don't want to break anything expensive and its all expensive. I drove the car to work and dropped it off at the building car wash kiosk. Later at 5:00PM I picked it up, started it up and it ran a little rough at idle. I didn't get more then 5 miles down the road and felt no power. It was like driving an old VW (sounded like that too). I went right to my mech shop and he tested compression. The whole right side was 40-50psi ! He said the wash guy must have over-reved it or I must have seriously down-shifted at some point. Upon taking the heads off we found those small half moon markings on top of the 3 pistons. He said I "kissed" the exhaust valves and that was the lost of comp. Question #1 -I didn't down shift as suggested but even if I had, would this cause the pistons to catch-up with the valves and touch? #2 - another guy said it could have 'jumped" a tooth on the cam sprocket ?? #3 - does this mean I can't rev the engine at all?? Anybody's experience with this issue that wants to chime in would be appreciated as I am at total loss that any of these two possibilities could cause this much damage to a pampered car.

Thank you all in advance

MV in Miami
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Manny V
Old 05-20-2010, 02:10 PM
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Join Date: Jul 2006
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An old friend used to work at a car wash some 25+ years ago.
I heard some stories..

..good chance some irresponsible dumb kid at the car wash wanted a quick thrill with your car.
Old 05-20-2010, 03:09 PM
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Never Valet. Never give keys to cash wash attendant. Looks like a very hard, very expensive lesson. I am sorry...
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86 930/4 tribute beasty
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Old 05-20-2010, 03:24 PM
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Any video cameras in the area? Did you check the vehicle mileage? Ferris Beuler comes to mind...

Its odd that only the valves on one side hit...

Was the cam timing done correctly after the rebuild? Sounds like it may be off...

Sorry!
Old 05-20-2010, 04:33 PM
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mark '87 930's Avatar
 
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Garage
don't do this either..
http://www.theglobeandmail.com/globe-drive/car-life/cheney/globe-journalists-son-crashes-180000-porsche/article1574334/


Sorry about your car.
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Old 05-20-2010, 05:16 PM
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The fact that the damage occured on one side and not the other might indicate a cam timing issue. One cause might be a collapsed tensioner. Another might be improper torque on the cam retainer nut, or forgeting to install the cam locking pin.
The upside to all this is that there are no holes so 3 new ex. valves, maybe some new guides,
and touch up the valve seat and you will be back in business.
Heed what the first 2 guys said about letting someone else drive your car. Ever.
Old 05-20-2010, 06:22 PM
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Never let anyone touch your car$$$$ besides you and your mechanic...

Sorry..............


Walt
Old 05-21-2010, 11:06 AM
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What caused this

Can't thank you all for all the good info an help on this issue. I did find out two important things in all this expensive mess. #1 - two idiots here, the guy that I gave the keys to and the bigger Idiot......ME. #2 - Pelican has once again shown that you can't find a better, more knowledgeable group of people when you're in the woods. Thank you for all your help. Lesson learned Wash my own damn car and keep the keys in my pocket!

MV
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Old 05-21-2010, 05:25 PM
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