Compression Test?
roper1
03-17-2009, 09:57 PM
I have a 94 Chrysler LHS with the 3.5 liter motor and this bad boy has the infernal running hot issue I changed the water pump, hooked the radiator fans up where they would run all the time worked for a while then got hot again, did everything that is listed here on this forum except do a voodoo ritual and this bad boy still runs hot! My big question is can I run a compression test on each cylinder to determine if I have a blown head gasket without taking the heads off?
Any help will be greatly appreciated!
Any help will be greatly appreciated!
AWP9521
03-18-2009, 06:55 PM
Including purging the air out of the cooling system?
RahX
03-18-2009, 07:19 PM
Yes, those things are a pain to burp. Did you replace the t-stat too? Lift the front end off the ground and open the bleeders WITHOUT the engine running then start and run the engine without the radiator cap on for a bit and top it off and see if that helps.
tempfixit
03-20-2009, 12:37 PM
Yes you can test without removing heads.
Most say to do a compression test with a engine at normal operating temperature, but that scares me for the reason of when removing spark plugs on a warm aluminium head you can scre up the threads, then it is heilacoil time or different head. You could remove the spark plugs with engine cold first then install to make sure that spark plugs are easier to get out with once warmed up.
1- Remove fuel pump fuse and start engine let run until it dies.
2- Remove all spark pkugs
3- Open throttle to full throttle position.
4- Turn the compression tester into spark plug holes 1 clyinder at a time
5- Crank engine over 3-4 revolutions and record reading.
You can either rent a compression tester from parts stores or buy one. Harbor freight has them for about 10 bucks.
I would do as others have suggested first.
Another test before doing compression test is if you know that the system is purged completely, then use a coolant pressure tester and crank the engine over or start it and see if the sytsem builds pressure immediately. If it does or you notice air bubbles in the coolant resorvoir while running you may have a bad gasket or a internal crack in head or block. You can also rent coolant pressure testers at parts stores.
are you loosing coolant or see white smoke out of tailpipe along with excessive moisture dripping at tailpipe.
Most say to do a compression test with a engine at normal operating temperature, but that scares me for the reason of when removing spark plugs on a warm aluminium head you can scre up the threads, then it is heilacoil time or different head. You could remove the spark plugs with engine cold first then install to make sure that spark plugs are easier to get out with once warmed up.
1- Remove fuel pump fuse and start engine let run until it dies.
2- Remove all spark pkugs
3- Open throttle to full throttle position.
4- Turn the compression tester into spark plug holes 1 clyinder at a time
5- Crank engine over 3-4 revolutions and record reading.
You can either rent a compression tester from parts stores or buy one. Harbor freight has them for about 10 bucks.
I would do as others have suggested first.
Another test before doing compression test is if you know that the system is purged completely, then use a coolant pressure tester and crank the engine over or start it and see if the sytsem builds pressure immediately. If it does or you notice air bubbles in the coolant resorvoir while running you may have a bad gasket or a internal crack in head or block. You can also rent coolant pressure testers at parts stores.
are you loosing coolant or see white smoke out of tailpipe along with excessive moisture dripping at tailpipe.
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