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Old 01-22-2009, 11:57 AM   #1
k22addict
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Default compression and leak down test on an 04 sti

kind of a dumb question but..... is there any other way a compression test or leak down test for that matter can be performed with the engine out of the car?
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Old 01-22-2009, 06:15 PM   #2
Franko
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Well usually you want an engine warm to do either because the results will be lower when it is cold due to everything being looser. You can perform a leakdown easily. Piston at top dead center on the compression stroke (valves closed) and whack it to her. Results will generally be a bit lower like I said.

A compression test will be a bit more tricky to do since usually you need to crank the car over with the starter to get compression. Although I dont think it will really be nessicary since the leakdown will tell you if you have a healthy engine or not.
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Old 01-22-2009, 08:03 PM   #3
k22addict
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Quote:
Originally Posted by Franko View Post
Well usually you want an engine warm to do either because the results will be lower when it is cold due to everything being looser. You can perform a leakdown easily. Piston at top dead center on the compression stroke (valves closed) and whack it to her. Results will generally be a bit lower like I said.

A compression test will be a bit more tricky to do since usually you need to crank the car over with the starter to get compression. Although I dont think it will really be nessicary since the leakdown will tell you if you have a healthy engine or not.
"whack it to her" please explain...im thinking some sort of baseball bat when i hear this
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Old 01-22-2009, 11:31 PM   #4
flycaster
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Heh, heh...yeah, I can see how the metaphor might be a little tough to follow. What he means is to pressurize the cylinder with a 100 psi shot from the leakdown tester. Some guys, me included, just say "shoot it", but "whack it to her" works too.
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Old 01-23-2009, 04:23 PM   #5
Franko
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Hehe, Yeah sorry about that. Just do a normal leakdown test and then if you find one cyl is exceptionally bad (over 20%) then do like 100 psi and you should be able to tell where its going. Listen in the exhaust, listen to your intake and take the oil cap off and see if its coming from there.

It might be hard to hold the engine at top dead center when you put 100 psi in the chamber so be prepared for the engine suddenly turning over.
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