I will prabably end up doing that... again. I had the head off and resurfaced when the problem first occurred 4 months ago and i couldn't find anything wrong beside a blown head gasket. It hasn't started since then...
I guess the pistons will have to come off this time unless it's just the rings not sealing due to carbon build up or washed out cylinders/contaminated oil with fuel due to flooding. I will try a last trick with ATF in the cylinders and also flush the e85 contaminated oil and see if it restores compression with fresh oil.
All coils fired at once. Engine blew?
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billr
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- Location: Walnut Creek, Calif. USA
Re: All coils fired at once. Engine blew?
" I had the head off and resurfaced when the problem first occurred 4 months ago and i couldn't find anything wrong beside a blown head gasket. It hasn't started since then... "
I wasn't aware of that, must have missed it previously in the thread. Was the block deck thoroughly checked for warpage? I assume you ensured the valves were all sealing before putting the head back on. Still, I think you are going to have to pull the head to solve this. I don't think any magic elixers (ATF, etc.) are going to restore compression.
I wasn't aware of that, must have missed it previously in the thread. Was the block deck thoroughly checked for warpage? I assume you ensured the valves were all sealing before putting the head back on. Still, I think you are going to have to pull the head to solve this. I don't think any magic elixers (ATF, etc.) are going to restore compression.
Re: All coils fired at once. Engine blew?
The head gasket must be sealing properly as i got a leak down tester last week instead of the compression gauge and i was able to see that the head gasket is sealing and the compression is leaking past the rings in the crankcase only. I wanted to check that before opening the engine. Since the piston looked like new on the top when i had the head off i don't think there could have been detonation breaking ring lands. Especially on 5 cylinders. So it could be just rings issue or sealing issue but could it cause compression as low as 40psi?
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billr
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Re: All coils fired at once. Engine blew?
What pressure do you use for the leak-down test? If it isn't up in the 100+ psi range it may be tough to tell if a gasket is leaking. Have you done a "wet" compression test? That should show if it is the rings leaking. In general, rings have to be pretty darn bad to leak that bad; I'm thinking this might be a valve-timing issue (again, assuming the valve sealing is known to be good). Have we discussed valve timing yet? Yes, I know you are feeling/hearing a lot of air coming out the crankcase. I'm just trying to throw out more ideas, but I still think the best one is to pull the head and start inspecting. You can even then do the individual pressurizing of each cylinder, eliminating all but the ring/piston/cylinder seal from the wonderment...
Re: All coils fired at once. Engine blew?
On the cylinder 6 it is able to keep pressure but on the others it is leaking so bad out of the crankcase that the leak down tester cannot even build pressure. Yes i did a wet compression test but it didn't change. I had cleaned the valves, reseat and clearances and they are all sealing perfectly. I get no air leaking in the exhaust or intake so i think timing is correct too. I will pull it appart this week...
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billr
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Re: All coils fired at once. Engine blew?
As you pull it apart, try the pressurizing again after the valve cam/rockers/whatever are removed, so that there is no chance the valves are being held open. It takes little extra effort to do and might reveal a new clue.
Re: All coils fired at once. Engine blew?
I let the cylinders halfway up soak in ATF for 3 days. I had drained the oil during a day before so i was able to collect only the ATF and there was some grim and black dirt in the ATF fluid when dropping it. It slowly leaked past the seals. However the one cylinder that had pressure already didn't leak as much.
I tried leak down test on the the cylinders now 1 and 2 and they were holding up 90psi without leaking anything this time. Whereas before it couldn't hold 20psi from leaking into the crankcase!! So it might be some sort of miracle lol.
I tested the compression but the readings are low (80psi) however the first stroke is equal in pressure to the other strokes so the rings might be good. I have a very tiny 1.6kg battery that looks off a bike and 4 years old. It was starting the 2jz fine but i think it gives me these low compression readings right now. I will try with a bigger battery tomorrow and letting battery charge hopefully it will start this time!
I tried leak down test on the the cylinders now 1 and 2 and they were holding up 90psi without leaking anything this time. Whereas before it couldn't hold 20psi from leaking into the crankcase!! So it might be some sort of miracle lol.
I tested the compression but the readings are low (80psi) however the first stroke is equal in pressure to the other strokes so the rings might be good. I have a very tiny 1.6kg battery that looks off a bike and 4 years old. It was starting the 2jz fine but i think it gives me these low compression readings right now. I will try with a bigger battery tomorrow and letting battery charge hopefully it will start this time!Re: All coils fired at once. Engine blew?
Hello guys,
It was the ringlands that were shot in the end.
No signs of detonation but the ringlands are smashed on 5 out of 6 cylinders. Keep in mind it happens the first few pulls under low boost that i did (about 5 pulls, one for each piston lol) only 6 psi. AFR were in the 10.6/11.5 range with E85.
I've rebuilt the engine with brand new OEM 2jz-gte pistons and the CR is now 10.4 instead of 10.5. The oem gte pistons looks much stronger than the ge vvti pistons with the rings further down and more material between them. Along with forged rods etc, the engine is ready to start again.
I am guessing either my timing map was bad maybe? I used some online for the base map but it might have been for a lower CR engine and mine is spooling very quickly/early. I am using a J&S safeguard too but maybe timing was too advanced and i was having preignition?
Otherwise seeing how sudden and brutal the failure was could it have been the LS2 truck coils firing too early? With the battery voltage correction while doing these pulls with 13.6volts i was seeing 4.7ms dwell in megalogviewer.
I have attached the msq file.
Thank you for the help!
It was the ringlands that were shot in the end.
No signs of detonation but the ringlands are smashed on 5 out of 6 cylinders. Keep in mind it happens the first few pulls under low boost that i did (about 5 pulls, one for each piston lol) only 6 psi. AFR were in the 10.6/11.5 range with E85.
I've rebuilt the engine with brand new OEM 2jz-gte pistons and the CR is now 10.4 instead of 10.5. The oem gte pistons looks much stronger than the ge vvti pistons with the rings further down and more material between them. Along with forged rods etc, the engine is ready to start again.
I am guessing either my timing map was bad maybe? I used some online for the base map but it might have been for a lower CR engine and mine is spooling very quickly/early. I am using a J&S safeguard too but maybe timing was too advanced and i was having preignition?
Otherwise seeing how sudden and brutal the failure was could it have been the LS2 truck coils firing too early? With the battery voltage correction while doing these pulls with 13.6volts i was seeing 4.7ms dwell in megalogviewer.
I have attached the msq file.
Thank you for the help!