Well last race of the year was in semis and felt the car hesitate - killed it and parked it till I could diagnose.
Well it did not take long to determine that #1 cylinder had no compression. Leaked it and heard the exhaust leaking. Pulled motor and tore it down Saturday.
Seems I got really lucky with virtually no head damage and very little to the piston.
Upon teardown there was antifreeze - very small amount in head valley and a little in the oil when drained.
Cylinder walls looked perfect not even a scratch. All bearing after 2 seasons look like new - still have the coatings on them and zero signs of wear. So pleased with that end.
I did detect a little rust on the block where the head coolant passage dead heads just adjacent to the valve that went. I am wondering if that area of the head gasket (cometic head gasket) may have been leaking and the water hitting that valve a little.
For the latter part of the season I was chasing a antifreeze leak that only showed up when I would trailer the car back and forth from the track (2.5hr drive). I would always see a little on the trailer floor - so I changed lower rad hose, clamps, tightened everything but it still seemed to persist. thought maybe it was splashing out of the overflow tank which is stock and near the area...
Anyways curious if anyone has seen this and might have a cause for the valve.
Motor is apart and I will have heads completely rebuilt. They have MANY years on them. I rebuild the motor every two years and it usually has 250-300 runs by them on it. I double every race.
This message has been edited. Last edited by: ski_dwn_it,
I had that happen once with worse result and my thinking was I had a valve hit piston that was slightly bent and shop just regroups it true and I think it was stressed and let go over time. No way to prove my thinking because I don’t remember exactly which one was where but that’s my thinking.
The piece that broke off on mine found three other pistons before I got it shut down.
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I ran steel 990 casting BBC cylinder heads on the BBC I had in my car at one point. I found toggling the water pump on and off to put heat in the engine (methanol), was causing # 1 exhaust valve to leak. I pulled the cylinder head a couple of times for repair during the racing season (I'd leak the engine every couple weeks as standard maintenance during the season). After the second go around, I stopped toggling the water pump on and off and the problem went away.
I never run my motor without the water pump on.
I toggle the fans at times but always afraid of getting hot spots in heads without pump on. I would rule out that in my cause. But thanks!
I don’t think you were getting much if any coolant into that cylinder. If you had gotten coolant in the cylinder there would not be as much carbon build up as you see. Coolant will sort of steam clean the carbon out. I think the valve just got old and gave up. Be interested in how much runout is in the seat. Too much runout will flex the valve leading to cracks and broken parts like you have now.
To ad to my previous post worn guides will also do this same damage.
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Just gonna throw this out there. Tracy Dennis once told me that contrary to what most people think this s—-t wears out. Think about that when you’re putting a zillion runs on your junk. Even those major parts need replacing once in awhile.
Clowns to the left of me, Jokers to the right. Here I am.......
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