Compression Questions!
5th Wheeling
Joined: Sep 2023
Posts: 47
Likes: 17
From: On a Dirt Road in BFE
Seems a little low but and I don't know where you but altitude does play a big part. Is this a rebuilt motor or a JY pull? If its been sitting it just may have gunk/rust in the rings and it might clean up. If its running ok I would run it a while and then recheck it.
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Trailering
Joined: Sep 2023
Posts: 20
Likes: 0
it’s a craigslist pull, and I’m at sea level. It was sitting for a few months I believe before I bought it. It’s making a popping sound as it idles. Maybe there is a valve sticking open on cyclinder 1?
Cargo Master
Joined: Mar 2007
Posts: 2,854
Likes: 1,036
Compression tests are done when the engine is hot. If it is not, then you really should not use your results and compare them with others [that are probably done hot].
If it is cold, then those pressures are probably ok.
I never ever take a used part and not go through it. Be it a transmission or engine. At a minimum, pull the heads, new rings, and bearings. I understand it's too late now, but I do not trust anyone trying to sell me stuff. I expect the worst and hope for the best.
If it is cold, then those pressures are probably ok.
I never ever take a used part and not go through it. Be it a transmission or engine. At a minimum, pull the heads, new rings, and bearings. I understand it's too late now, but I do not trust anyone trying to sell me stuff. I expect the worst and hope for the best.
5th Wheeling
Joined: Sep 2023
Posts: 47
Likes: 17
From: On a Dirt Road in BFE
Since its already in with new plugs/wires/etc and we've ruled out injectors -vacuum leaks - wiring. I would just run the **** out it for a bit put some miles on it and see if it clears up befoe digging in.
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Logistics Pro
Joined: Aug 2010
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From: Chillicothe
winder up and giver the Ole Italiano tune up.
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Hotshot
Joined: Nov 2017
Posts: 17,499
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From: Northern Ontario
Not necessarily..
Did you do a hot compression or cold? Just out of curiosity.
Ive used junkyard engines and second hand engines. Some were good, some had issues. I just dealt with the issues as required.
What made you want to check the compression?….
Edit. Missed your second post. Have you pulled valve covers and checked for stuck valves, bent rods?..
Did you do a hot compression or cold? Just out of curiosity.
Ive used junkyard engines and second hand engines. Some were good, some had issues. I just dealt with the issues as required.
What made you want to check the compression?….
Edit. Missed your second post. Have you pulled valve covers and checked for stuck valves, bent rods?..
Fleet Mechanic
Joined: Jul 2003
Posts: 1,844
Likes: 129
From: Atlantic Canada
I had to go back and read your earlier posts. This truck is a 1994 that was originally a SEFI 5.0 with MAF? If you have a code reader, you can initiate a KOER cylinder balance test. With the engine warmed up to operating temperature, run the test and see what the computer thinks. If it comes back clear, I wouldn't worry about it, at least not right away.
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