2013 GT500 random start issues after warmup

luillo

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Yeah that's my fear too. Who knows how the PO treated the engine but it does seem to have detonated, and oil blowby in only one or two cylinders does point to broken ring lands.
A borescope will confirm or rule out the diagnosis in addition to low cylinder compression.

Funny thing is that the car starts and run just about normal for the most part. Randomly shows low boost with no other engine issues, 5psi to 8psi. Definitely keeping the car under the car cover if final diagnostic is heavy damage on the bottom end. I still have to buy a house prior to deal with this shit.
 

luillo

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Got an appointment with the shop to do a leak down test next week but for now I am testing some theories I have after taking in consideration other things I noticed during the spark plug swap.

I had oil on top of the thread on the other side of the engine, not sure what is the cylinder number. The oil was just above the electrode closest to the valve cover but didn't pay attention to the other side where the worst plug was found, therefore, I decided to run a few miles and pull the all the plugs again to see what they look like.

All look great to include the one with the issue but found oil right on top of one of the spark plug right after I removed the coil. The spark plug with the issue; the one that showed detonation signs, looked great but had oil on top of the thread and ZERO below by the electrode. All the oil found was closest to the valve covers and not the cylinder.

I will wait to see what the leak down test shows but I am hoping for valve cover seals dried and letting oil down to the plugs. I hope that I just didn't pay attention prior to pull that plug and oil was there from valve covers leaking. The car still start, accelerate and run fine as far as I can tell.
 

luillo

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Well, not the worst news but not good either. Compression for all cylinders are 180-195 but leak down came a little concerning.
20-25% in the first run and then 10-15%

The shop told me is nothing to be overly worry but usually would prefer to see more consistent number I guess. He mention that rings might not be sealing perfect, therefore, could be a concern and the reason for the spark plug oil but I have 200 miles on them and no oil found yet.

At least I will have some life on that motor until I save to put a built long block.
 

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