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No compression in cylinder Head
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stepheme
Novice
Feb 12, 2010, 3:41 PM
Post #1 of 8
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No compression in cylinder Head
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I have a 2005 Chevy Aveo, I cracked the cylinder head in the engine about 1.5 months ago and we finally got it all put back together. My husband put two of the Cam Pullies in backward, the left on the right and the right on the left. Which caused it to be out of time. Before he noticed what he had done we tried to turn the engine over a three times. The Engine never turned over obviously, but it did crank pretty smoothly. Then he put it back in time and fixed his mistakes, and then it still wouldn't start. He checked the compression and there was no compression at all in the cylinder head. Several people have told us that sometimes you have to build compression in the head after the car has set for a while. Is that true?? If so, how exactly would you do it? Also if he possibly bent some of the cylinders, and it is back in time now, do we run the risk of him cracking the head or causeing further damage by trying to build the compression??
(This post was edited by stepheme on Feb 12, 2010, 4:57 PM)
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chickenhouse
Enthusiast
Feb 12, 2010, 4:58 PM
Post #2 of 8
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Re: No compression in cylinder Head
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Just curious, how did you crack the head to begin with? It sounds as though the valves have been bent by cranking the engine while out of time. Someone on this site will check to verify this engine is an interference engine and if so, looking at new valves-again. r
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Hammer Time
Ultimate Carjunky
/ Moderator
Feb 12, 2010, 5:08 PM
Post #3 of 8
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Re: No compression in cylinder Head
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Yes, it is an interference engine and likely has bent valves.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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stepheme
Novice
Feb 12, 2010, 5:17 PM
Post #4 of 8
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Re: No compression in cylinder Head
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We put a new head, new valves and all in after I cracked the old one. I cracked the old one by the serpantine belt shredding, getting up under the timing belt caused it to jump time, I tried to get it off the turnpike and ended up cracking the head. The car is now back in time and has a new head. He did try to start it while it was out of time, but never got it to turn over, and didn't really crank it much. We put oil on top of the pistons, let it set for a little while and then it started building compression. They got the compression up pretty good, the last time they checked the compression it was at 50 psi, but they built up more compression before trying to start it not sure how much because they didn't measure it every time and then put the fuel pump fuse back in and tried to start it again, and now they are back down to 25psi, it lost compression. Would compression build up if there where bent valves?
(This post was edited by stepheme on Feb 12, 2010, 5:22 PM)
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Hammer Time
Ultimate Carjunky
/ Moderator
Feb 12, 2010, 5:20 PM
Post #5 of 8
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Re: No compression in cylinder Head
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You cannot rotate an interference engine when it's out of time. It will take out multiple valves on the first revolution. Your going to have to remove the head again, send it to a machine shop and replace all the bent valves. You just learned an expensive lesson.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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re-tired
Veteran
/ Moderator
Feb 12, 2010, 11:43 PM
Post #6 of 8
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Re: No compression in cylinder Head
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A lesson to all diy'ers. When disassembling, mark your parts , nail polish works well , as does those little tags with strings to tie it on . Markers tend to rub off. Sure it takes time ,looks silly but how does it look and how much time does redoing a head job take.
LIFE'S SHORT GO FISH
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Feb 13, 2010, 9:46 AM
Post #7 of 8
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Re: No compression in cylinder Head
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Love it! Thought I was the only one. Clear nail polish (handy for asst things) in many tool boxes and found a whole asst of colors (very small bottles) for a buck at a dollar type store. Fast dry if warm. No I don't wear it and was shocked at stores what they get for that stuff!
Another: Turkey basters for removing brake fluid for new prior to bleeding brakes at master cylinders. Make sure those are well marked for what they are used for! NEVER AGAIN FOR FOOD!
T
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nickwarner
Veteran
/ Moderator
Feb 16, 2010, 12:06 AM
Post #8 of 8
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Re: No compression in cylinder Head
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unless of course the food is being made for someone you really don't like.
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