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Post by sourcelx on Feb 10, 2010 18:15:33 GMT -5
So my motor have one cylinder reading zero compression. Story: I recieved my new cams and some used(look great) arp headstuds. I installed them both. had a little trouble getting the car running but eventually did by keeping it at around 2k then turning the biss most of the way out. the car ran ok on the way home and to work and back. I noticed then that the old dried out cam seals were leaking. So I took everything back apart and replaced them. Got it all back together and was barley able to start the car( only able to keep it running by keeping foot on throttle). I drove it and it felt horrible. I then did a compression test and got thies results from right to left. 150, 130, 100, and 0 I assumed the headgasket was the problem. I pulled it apart, slapped on a cometic head gasket. The old gaket wasnt blown out but had alot of oil between the left 2 cylinders. I cleaned it and put her back together. Start her up and it feels like nothings changed. So, I do a compression test and get, (from right to left 140,13x,13x,0 (all done on a cold motor with a closed throttle plate)). Now Im wondering what would give me a reading of zero compression. The pistons looked fine. I didnt look to hard but the valves looked aight. Rings? Headgasket? Piston? Burnt valve? or the new cams? Any other ideas would be great. Im about to drop some oil into the cylinder to see if it improves any... Thanks -Edwin
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Post by doggietom on Feb 10, 2010 18:39:01 GMT -5
Possible causes: Broken pisron ring Hole or crack in piston Cracked head or block Boken head gasket Extremely worn or scored cylinder wall Stripped park plug threads (unlikely) Valve or valve seat problem washed out cylinder
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Post by sourcelx on Feb 10, 2010 19:05:21 GMT -5
Possible causes: Broken pisron ring Hole or crack in piston Cracked head or block Boken head gasket Extremely worn or scored cylinder wall Stripped park plug threads (unlikely) Valve or valve seat problem washed out cylinder rings-possible hole/cracked piston- unless its on the side, I seen nothing broken head gasket- this one is doing better on every other cylinder than the last worn or scored walls- I rotated it when I had the head off and seen no scores, and one cylinder being that worn is crazy stripped plug thread- they seal tight valve/seat prob- Im thinking burnt valve/s washed out- doesnt seem like it Thanks, keep the ideas and suggestions coming
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Post by prdsm on Feb 10, 2010 19:25:35 GMT -5
drop a little cap full of oil down in the cylinder through the spark plug hole and rotate the motor like 2 times then do the compression test. it will show if the rings are bad. if you get compression.
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Post by laser92 on Feb 10, 2010 19:38:34 GMT -5
I say headgasket most likely, most valve issues will still show some compression. The only valve issue I've ever dealt with that had 0 compression was a burnt valve that was missing a triangle out of the valve itself. It looked like a cameltoe...
Most other issues will still read 20-40 that I've seen, unless there's a hole in the piston, but you'd know that by the sound it makes when turned over. There's no missing that one.
valves- no, you said they looked good, may be an issue there, but wouldn't read 0.
cams- no, it had 0 before the cams were installed
pistons- no, said they looked good, could still be a ring/land issue, but more than likely again would read some compresson, plus would make a nasty sound, and more than likely would have seen scoring in the cylinder walls which you said were also good.
plugs- no not enough to read 0 again
My money is on the headgasket, but why it's bad again is going to be your issue, was the deck true? head? no cracks? Oil around the two cylinders is where I'd start looking, that seems to be the point of failure, passages on the head in that area were ok?
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Post by BLUE71NOVA on Feb 10, 2010 19:57:38 GMT -5
cams- no, it had 0 before the cams were installed My money is on the headgasket, but why it's bad again is going to be your issue, was the deck true? head? no cracks? Oil around the two cylinders is where I'd start looking, that seems to be the point of failure, passages on the head in that area were ok? He said it started after the cam and headstud install. My money is on valves hanging on one cylinder, or the headgasket. The deck and head surfaces must be perfect for a cometic to seal right. They claim a 50 RA or better, thats a damn near perfect surface. Rings or piston lands maybe the culprit judging by the oil, and you wouldn't be able to see that without disassembly.
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Post by sourcelx on Feb 10, 2010 20:36:39 GMT -5
Yea, it wasnt till after the install that I had 0 compression. I didnot get it decked like I probably should have though. I plan on dropping some oil in there asap when I get some time and this weekend Ill be pulling the head off again. Thanks for the input guys. -Edwin
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Post by 6bolt2g on Feb 10, 2010 21:27:28 GMT -5
I would say valves. Did you compress/bleed the lifters before you put the new cams in. Probably didn't let the valves close all the way and smacked the piston.
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Post by 92redLaser on Feb 10, 2010 21:50:30 GMT -5
we have that 2g head still the valves and all were good if you wanna try it out
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Post by Green92gsx on Feb 11, 2010 7:01:43 GMT -5
Check that cylinder for valve /piston contact. Perhaps after the cam install the lifter's didn't bleed down all the way causing the valve to hang open.
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Post by wishihadatalon on Feb 11, 2010 8:21:33 GMT -5
Im with Angelo and Jeremy here. Bleed the lifters and double check to make sure the valves and the pistons haven't touched.
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Post by 99gst_racer on Feb 11, 2010 10:33:15 GMT -5
You really need to use a leak down tester to see where you're leaking cylinder pressure.
I have one that you can borrow if you need one.
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Post by sourcelx on Feb 11, 2010 13:40:49 GMT -5
You really need to use a leak down tester to see where you're leaking cylinder pressure. I have one that you can borrow if you need one. That would be great but your not that close and I dont have the most reliable vehicle( fathers truck) right now.
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Post by sourcelx on Feb 11, 2010 14:26:28 GMT -5
Just added some oil to the cylinder and did a comp test and still read zero. So unless a ringland is blew out I think the rings might be ok.
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Post by 99gst_racer on Feb 11, 2010 16:36:46 GMT -5
You really need to use a leak down tester to see where you're leaking cylinder pressure. I have one that you can borrow if you need one. That would be great but your not that close and I dont have the most reliable vehicle( fathers truck) right now. I'll be at the Intersection in GR friday night and I'll be at Street & Strip in Otsego on Saturday, so I could bring it with me if you wanted to meet up. But at this point, you've already narrowed it down enough to know that it's probably valve related and you'd have to pull the head anyway... But if you do still want to do a leak down test, just let me know.
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