964 will not start after shift

[allen8590]

I was driving my 964 C4. I had a bad shift, and think I may have over revved the engine. I thought I noticed a change in tone, so I pulled over and shut it off. After looking around under the hood and everything looked fine, I attempted to restart with no luck. The engine turns over, and seems to sound normal when doing so. Any ideas? Thanks in advance

[ischmitz]

Are you saying the engine was running after the "event" but sounded different? And then you shut it down, tried to restart and it wouldn't start?

If that is the case I would alomst be certain you have lost compression on some cylinders. I would take it to a shop and have then check compression/leakdown. Also check for broken rockers. You might have floated the valve train and made contact between valves and pistons.

Good luck and keep us posted,
Ingo

[allen8590]

Yes, the engine ran for a minute or so after the event until I could get off the road and shut it down. Whats an estimate of what I might be looking at to have this issue fixed by a shop? Thanks again

[ischmitz]

If you really did hit the valves you pretty much look into a full top-end rebuild. Depending on who does the work you need to prepare for 3k (bare machine shop/parts costs) up to 6k if you ley a shop do the work.

Then there is the issue with the rod bolts - they do not like to be reved to begin with and I highly recommend changing them to ARP or Raceware. This can be done without splitting the case.

Where are you located? Maybe you can do some work yourself with the help of fellow Pelican members.

[allen8590]

I am going to take the car in tomorrow. Thanks for the heads up. I have a few additional details I wanted to throw in, but not sure how relevant they are. It seems my fuel was low/out as well (unaware if I actually ran out amongst all this). I added a few gallons of fuel. If I did do what we suspect, would the car sound normal when attempting to start it(turning over)? There is no abnormal smoke from the exhaust, but I do smell a rich fuel smell as if its flooded. Just wanted to hit on some additional details as well before my engine gets taken down. Thanks again for everything.

[ruf-porsche]

If you smell fuel, the engine is flooded, and like my Dad use to tell me you can crank until the cows come home, but the engine is not going to start. You need to remove and dry out all the wet plugs, or replace the plugs with new one. You may want to blow a little compress air into each cylinder to get rid of any gas. Take all precaution when doing this such as not smoking or have an open flame nearby and have a fire extinguisher on hand.

[allen8590]

Well I know I lost compression on 1 bank for sure, there is nothin there. Are there any simple options I can upgrade with the valve train or anything else other than the rod bolts? Thanks again.

[Wayne 962]

Hi there. The details don't completely add up for me here. I would think if the engine was running afterwards and then you shut it down, it should start up again. Unless the engine wasn't really running, and you were just coasting with it in gear to the side of the road? How did you check the compression? If you ran a compression check did you remember to put the throttle all the way open during the test (common error).

thx,

Wayne

[175mph951]

sounds like bent valves....and as said earlier i'd definitaly change the rod bolts, 3.6 rod bolts are bad enough let alone on a car that was over revved

[allen8590]

Wayne, love your books! Yes, the engine was running, until I shut it off. It ran for around another minute as I pulled off the road. I had a local Euro shop do a leakdown/compression test for me and all I know at this point is that 1 bank has no compression. Is it common for only 1 bank to go bad in this situation?

[ruf-porsche]

Broken rockers on that bank of cylinders. Pull the valve cover and check the rockers. Happens when an engine is over revved.