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stevey88
Samba Member
Joined: January 16, 2008
Posts: 1317
Location: Fremont, SF Bay Area
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 Posted: Sat Dec 05, 2009 4:22 pm Post subject: Compression test |
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I know the compression test is supposed to be done with a warm engine. But should I expect the readings to be very different when the engine is cold ? Will the readings be higher/lower with a warm engine or the readings is just unless when taken with a cold engine ? I ask this because I am testing an engine without coolant and it will be a lot of work to hook the cooling system up as I do not have a radiator.
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Steve
87 Westfalia full camper 4 speed |
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tencentlife
Samba Member
Joined: May 02, 2006
Posts: 10078
Location: Abiquiu, NM, USA
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| Posted: Sat Dec 05, 2009 5:13 pm Post subject: |
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| or the readings is just unless when taken with a cold engine ? |
Seems like a word missing here or something, if this was an important part of your question then please clarify.
Cold comp test will typically read higher, like 15-20%, and also more consistent cylinder to cylinder. That may hide problems that a warm test reveals. In any event, I don't put much stock in comp tests with the hydro lifters unless conditions are carefully controlled. Especially with an engine that is not installed and ready to run, a leakdown is easier and will provide more and better info than a comp test. If you slacken the rocker sets and do leakdown you get a picture of cylinder sealing in isolation from the valvetrain, which is really what you want to assess, rings and valves.
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stevey88
Samba Member
Joined: January 16, 2008
Posts: 1317
Location: Fremont, SF Bay Area
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| Posted: Sat Dec 05, 2009 7:12 pm Post subject: |
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10c,
Yes, I mis-type. it should read useless and not unless. I do own a lead down tester and I will do a lead down test.
I was trying to determine if I can just do a head job ( evident of slight head leak ) or need to split the case for a full rebuilt. I can't do a real oil pressure test as I can not heat the engine up too much.
Thanks for the answer.
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Steve
87 Westfalia full camper 4 speed |
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