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Porsche Techs! 992 4S, dead cylinder 8000 miles help!
Here's my story. I bought a non running 2020 992 4S with 8000 miles. Bought it from Porsche Financial as a repo, no starter engagement. Took it to Porsche because it was still under base warranty. They replaced the starter and got it cranking. It almost started but was uneven. Performed compression and leak down. Found all compression good exempt #5 cyl had non. Inspection showed 2 very bent exhaust valves (different cams). They have not seen this before and they are not sure what would have caused it. They want approval to remove the engine to inspect failure. Depending what they find it may or may not be warranty . My question is what could cause this and is it worth the gamble to have them go further or should I just replace it with a used engine that I would swap. Thanks for any help.
I finally received the used/new 2000 mile engine from Germany. It sat at Fedex awaiting customs clearance for 3 weeks, which was very painful. Last weekend I did the swap with my 2 boys helping to lower, mate and reinstall. It went great. I did have to switch more than I hoped because of my PDCC system. In addition to the pump I also had to switch the oil cooler and the wiring harness off my old engine because of 1 plug on the hydraulic pump. It fired right up and I have put only 75 miles on so far. Super fun car having never driven one. Crazy shifts. Still learning the buttons and it's driving characteristics. I'm not sure what to do with the old motor. Thinking of selling it as-is instead of tearing it down to see the failure in cly 5.. Let me know if anyone is interested. Thanks for following. It goes back to Porsche for a new windshield and trim piece replacement that was ordered back when they had it. Those parts are still not in. The warranty expired while in their possession. The RF speaker is blown and rattles so getting that on order. Ready for date night with the wife!
Previous owner screwed it before repo? Remove spark plug add small nut or bolt and replace spark plug is my guess, probably lost a huge deposit with repo.
Very strange. Sounds like the timing is off and the valves hit the pistons. Perhaps a timing chain tensioner failure. I haven’t heard of that, but it sure seems that your engine is toast. The only way valves can bend is if they hit the pistons.
Is it a manual. A “money shift” could cause significant over rev where the valves float and hit the pistons. That’s my guess. I actually think a failed timing chain tensioner is unlikely. I think it was over reved. That should be easy to check.
Last edited by Denny Swift; 10-17-2023 at 10:47 AM.
How long did you have it before it failed? Did Porsche offer it as a normal running car or CPO? Was there are any notices or disclosures for this purchase?
Previous owner screwed it before repo? Remove spark plug add small nut or bolt and replace spark plug is my guess, probably lost a huge deposit with repo.
Clearly you've never tried to remove / replace a spark plug in a 911. It isn't exactly easy........
I wonder if this is going to be yet another of those “unusual” first posts, where the OP never replies. I hope this isn’t one of those. I’d really like to hear how this turns out.
BUT, lots of pieces to this puzzle are missing. Such as…
Does it make any sense that someone would buy a vehicle that doesn’t run, and write the check before any diagnostics are done? He says they tried to start it, and found the bent valves, AFTER purchase. Would a dealer actually sell a vehicle with undiagnosed issues???
Does it make any sense that someone would write a check for a non-running vehicle BEFORE asking for an over rev report?
Does it make sense that a Porsche mechanic would replace the starter and just try to crank the engine without running a full diagnostic first?? I’d never do that. Just cranking it could bend valves if the timing were off.
There is a lot of missing information that needs to be provided before I believe this is real.
If it is, I certainly hope it works out, and I don’t want to beat up on someone who has a serious problem, but this sure smells fishy to me. These stories almost always come via a member’s first (and often only) post.
Last edited by Denny Swift; 10-17-2023 at 02:49 PM.
Does it make any sense that someone would buy a vehicle that doesn’t run, and write the check before any diagnostics are done? He says they tried to start it, and found the bent valves, AFTER purchase. Would a dealer actually sell a vehicle with undiagnosed issues???
Does it make any sense that someone would write a check for a non-running vehicle BEFORE asking for an over rev report?
I wonder if this is going to be yet another of those “unusual” first posts, where the OP never replies. I hope this isn’t one of those. I’d really like to hear how this turns out.
BUT, lots of pieces to this puzzle are missing. Such as…
Does it make any sense that someone would buy a vehicle that doesn’t run, and write the check before any diagnostics are done? He says they tried to start it, and found the bent valves, AFTER purchase. Would a dealer actually sell a vehicle with undiagnosed issues???
Does it make any sense that someone would write a check for a non-running vehicle BEFORE asking for an over rev report?
Does it make sense that a Porsche mechanic would replace the starter and just try to crank the engine without running a full diagnostic first?? I’d never do that. Just cranking it could bend valves if the timing were off.
There is a lot of missing information that needs to be provided before I believe this is real.
If it is, I certainly hope it works out, and I don’t want to beat up on someone who has a serious problem, but this sure smells fishy to me. These stories almost always come via a member’s first (and often only) post.
OP said it was bought as a repo, non running car so it was probably very cheap.
Sorry I was not getting email post notices, just logged it, It's a PDK. I have been looking to buy one of these for about a year and have seen salvage title ones doing what I paid for this. I am a used car dealer and it was bought cheap enough to replace the engine but I don't want to waste money if Porsche feels it's not going to be warranty. $7500/30 hrs to remove engine tear down and investigate and install the same motor if not warranty. If nothing is found abnormal they will order a long block and install it under warranty. They did borescope the cylinder, piston and cylinder wall look fine. Motor cranks with no abnormal noises. They are working on a quote for a long block if customer pay but I'm sure it will be a ton. They have not seen anything like this. Could it have hydrolocked at some point? But just to exhaust valves?? I am familiar with engines but not these...yet
Sorry to doubt you! Thanks for the additional information.
Hydro lock seem unlikely, and I’d think there would be signs of water in the air filters. It should be pretty easy to rule that out. Plus only affecting one cylinder is strange. Lifter failure? I think things are looking in your favor. Either lifter failure or valve spring failure would be my guess now. Both would be covered under warranty. Since it’s a PDK, that rules out a money shift and less opportunity for them to blame it on operator error. It seems that it should be pretty easy to diagnose lifter or spring failure by removing the cams and inspecting the valve train components. But they’d have to remove the engine. I honestly can’t think of any other way the valves could be bent. I think it would be pretty easy to check the timing, and if it was off, I’d expect it to damage other valves as well. To me, it looks like they are going to be hard pressed to claim that the cause was anything other than mechanical failure. Best of luck.
You would likely be stunned at the cost of a new engine for a 992. They are on the order of $ 70,000. Warranty is your only way out of this mess, let the dealer have it and do what they have to, keep your fingers crossed for a no-hassle warranty replacement. Good luck.
10-16-2023, 09:43 PM
Porsche Techs! 992 4S, dead cylinder 8000 miles help!
