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Questions on Engine Failure

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Old 07-15-2018, 11:23 AM
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stoessjc
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A friend of mine's C6 z06 engine failed. On inspection, it appears engine mount failed and allowed the engine to move enough to pinch off one of the oil cooling lines, thus starving the motor of oil. Connecting rod broke and shot through the block. He has bought a new motor from GM ($12K). A couple questions posed here:

1. Has anyone heard of a failure like this involving a motor mount?

2. Should he have the dropped valve problem addressed (not sure if that was only a problem with a run of motors in the past or an inherent design problem on all ls7 motors)?

Thanks for any feedback.
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Old 07-15-2018, 11:38 AM
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427V8BB
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Originally Posted by stoessjc View Post
A friend of mine's C6 z06 engine failed. On inspection, it appears engine mount failed and allowed the engine to move enough to pinch off one of the oil cooling lines, thus starving the motor of oil. Connecting rod broke and shot through the block. He has bought a new motor from GM ($12K). A couple questions posed here:

1. Has anyone heard of a failure like this involving a motor mount?

2. Should he have the dropped valve problem addressed (not sure if that was only a problem with a run of motors in the past or an inherent design problem on all ls7 motors)?

Thanks for any feedback.

yes no matter what get the heads fix ASAP I felt like death driving on stock heads. And hmmm rod failure

ans did he not notice low oil pressure or low oil or something

Last edited by 427V8BB; 07-15-2018 at 11:38 AM.
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Old 07-15-2018, 11:47 AM
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Unreal
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Motor mount failure is common on all vettes bit never heard of it causing an issue besides a clunk .

Yes heads need to be addressed.
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Old 07-15-2018, 12:24 PM
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What year is the car out of curiosity? Heads will need to be addressed at some point. Pity he already paid $12K for a stock motor...
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Old 07-15-2018, 01:31 PM
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LV Vette
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Originally Posted by MTPZ06 View Post
What year is the car out of curiosity? Heads will need to be addressed at some point. Pity he already paid $12K for a stock motor...
AHP offers a forged LS7 blueprinted motor with the head fix for $15,000. There are also a number of upgrades available for it also. Maybe you can cancel or return the motor???
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Old 07-15-2018, 05:35 PM
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Originally Posted by Unreal View Post
Motor mount failure is common on all vettes bit never heard of it causing an issue besides a clunk .

Yes heads need to be addressed.
Just want to be sure on the issue to cylinder heads. The motor he bought is a long block with new cylinder heads. Does he still need to remove the new heads and have them worked on to resolve the drop valve problem?

the AHP motor might have been an option but think it is too late for that.
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Old 07-15-2018, 05:40 PM
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^Yes, new GM heads are still an issue.
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Old 07-15-2018, 09:58 PM
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My motor dropped a valve and blew up. I'm happy to say that AHP is building my new motor for me with a bunch of great upgrades. Should have it soon can't wait!! It's nice to actually know the person building your motor and also see it being put together by that person.
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Old 07-16-2018, 12:33 AM
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Heard of engine mounts failing. While I have not heard of engine mount failure causing an engine failure due to pinching-off an oil line but, given how the oil lines are routed and how they might be affected by engine movement, I can see how such a failure could happen.

Should you preemptively remove the heads to assess any potential problem with valve seat concentricity? Well...that's an awfully expensive way to proceed, but if your anxiety about possible valve guide wear is at a very high level, there's no way to accurately determine if there's a problem with seat concentricity other than removing the heads, disassembling them and measuring valve seat run-out.

As for dropping valves, keep in mind that guide wear has to be significant with the engine subjected to fairly severe duty before it will break a valve.

If it were me, I'd put the new engine in then run it 8000-10,000 miles. If you get to that point and the engine is demonstrating symptoms of excessive guide wear, then you can pull the heads, measure the actual guide wear and valve seat run-out then make repairs as necessary.

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Old 07-16-2018, 02:30 PM
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Owner may want to throw in some more rigid motor mounts...Hinsons or AMT. If the owner is nervous about this happening again (I'd say odds are equivalent to a being struck by lightening while holding the winning powerball ticket)...he could always upgrade to the ZR1 oil cooler/heat exchanger which eliminates the front mount oil cooler and lines. His new motor will have the bosses in the oil pan for it to bolt up...heck, it may even come with it depending on how the motor was dressed upon purchase. Solves the low oil temp issues on street driven C6Z's as well...that's what I did.
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Old 07-16-2018, 02:38 PM
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Shouldn't the new motor be covered by GM?
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Old 07-17-2018, 01:53 AM
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Originally Posted by SocalChvy View Post
Shouldn't the new motor be covered by GM?
It is, but not from a motor mount breaking thatís a wear item and some how caused the oil line to break and loose oil. Nahhh it ainít happing
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