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Cylinder 1 Valve Failure; Catastrophic
Topic Started: Feb 23 2012, 01:20 PM (864 Views)
Mikemetro
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So here is an issue I have come across 3 times in the past year. About a year ago I picked up a bunch of parts from a guy for 25 bucks. Starter, alternator, AC Compressor, and the head with intake and TB. He blew the old engine. The intake valve broke off a quarter of an inch from the base of the stem. When i pulled it apart the stem came right out. No obvious issues other than it appears the valve just broke off and bounced around destroying the head. About 4 months back I borrowed my parents 92 vert to go and swap with my daughters 92 vert that was blowing the ignition fuse. On my way to rescue her, my parents vert suddenly lost power. We loaded it on the tow dolly and got her home. we knew it was bad when we could not remove the number 1 plug to do a compression test. Pulled the head and found the number 1 intake valve broke in the same spot as the one i found a few months back. Needless to say the piston was destroyed as well as the head but amazingly there was no scarring on the cylinder walls. So now last week my other daughter called me on her way home from work. She has a 91 vert. She said the car just lost all power. So after i towed that one home I found a bad plug wire. Actually it fell apart when i removed it from the spark plug. So I figured I'll just give her a tune up. Removed #3 plug. looked good. Removed #2 plug. Looked good. Went to remove the number 1 plug. No Go. I knew what i was in for. So I muscled out what was left of the plug, looked inside. I could see the hole in the piston. So i pulled her apart. I was not so lucky. The piston cracked and scored the cylinder wall. Same issue as the other two. number one intake valve. But pieces of the pulverized piston went back up into the intake manifold and found there way into the number 2 and 3 cylinders. Warping the number 2 intake valve. So as I'm in the process of rebuilding the engine I wonder just how often does this happen? What could be the cause? On the rebuild i am using all new valves and valve guides(I'm using a spare block and head I had already) New pistons too. But there is no obvious reason for this failure other than just the valve breaking due to fatigue. But why the intake on number 1. And on 3 separate engines.
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Old Man


do you know the miles on each of those three?
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Mikemetro
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Old Man
Feb 23 2012, 01:26 PM
do you know the miles on each of those three?
Around 120k on my parents. And closer to 150k on my daughters
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3tech
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I've never seen it happen, and I think this is the only time I've ever heard of it happening. It's not common.
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idmetro
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Never had one break (knock on wood) but have burned several over the years. Any other symptoms prior to the valves breaking - ran really rough, poor mileage, etc.?
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Woodie
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I've never heard of it on a G10. I think idmetro is on to something. Engines had been running poorly for thousands of miles before this sort of carnage finally brought the abuse to a halt. I've seen this happen when people use starting fluid to get a worn out engine running every morning.
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Murf 59
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Very rare indeed. A local friend gave me a G10 block he had that dropped the #2 exhaust valve. But that is the only one I have seen.
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Mikemetro
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Turns out I was slightly mistaken. I dug out the old head that I picked up and it broke the intake on number 2. But the other two it was the number 1 intake. I'll post up some pics later of two of the heads that I have. The third one my dad used as a core for his replacement head. As far as performance. Both verts were the automatic. My daughters 91 ran smooth and other than having to replace the cam and crank seal it was sound. My dads 92 also was mechanically sound. Compression numbers on the 91 were 190/190/192. His on the 92 were in the 180's. I drove both of them prior to the failures. The 91 had plenty of getup and go but his felt sluggish in comparrison. As far as the other I have no data other than the obvious. I'll post some pictures of the two I have in my possesion as well as the piston carnage. The reason for the concern is that when I rebuilt my wifes 91 hatch I did not replace the valves. Just cleaned and lapped. The car only had 100k on it. Belonged to an old lady down in Sarasota. The reason for the rebuild on hers was a stuck oil ring due to it sitting for so long. That and every seal was dry rotted.
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