Compression test??? - Team Camaro Tech
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post #1 of 10 (permalink) Old Sep 26th, 01, 12:24 PM Thread Starter
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Well after my mishap..Read other post..It was recomended to me to do a compression test to make sure everything was alright...Did a test on all cylinders..all were at 148psi..Is this good pressure???Should they all be the same??what does a compression test check???..I mean what would a compression check tell me other than the comp pressure..Thanks in advance...

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post #2 of 10 (permalink) Old Sep 26th, 01, 01:30 PM
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148 psi is good. A compression test is a good way to find out if anything internal has failed (like burnt valve, hole in piston, broken rings, blown head gasket).

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post #3 of 10 (permalink) Old Sep 26th, 01, 03:14 PM
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All 8 cylinders are exactly the same? I've never got that result myself. Are you sure your gauge is good? Is it the screw in or the push and hold type? I'm not saying the test is wrong just never seen one exactly the same in all cylinders personally. I also do a leak down test.
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post #4 of 10 (permalink) Old Sep 26th, 01, 03:58 PM Thread Starter
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The gauge is new..One of those screw in types..The reading were all very similiar..

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Retored 76 LE Trans Am 455 4 speed..# matching
-------------------------
Restored 68 Camaro R/S 327 4 speed
-------------------------
Restored 55 chevy Belair
Blown, Fuel Injected

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post #5 of 10 (permalink) Old Sep 27th, 01, 06:16 AM
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A compression test give you an overall condition of your engine but to be more specific on what is wrong you might want to perform a leak down test. This one involves a little different tool in which you apply 100psi to each cylinder (one by one) and compare the differential pressure in a second gauge. If you have, I think, more than 10% psi leak down on a cylinder then you can check for different noises in different parts of the engine. Noise thru the carb means an intake valve leaking in that cyl. Thru the exhaust the same but an exhaust valve leaking. Bubbles in the radiator a leaking head gasket. And if the noise can be heard at the valve cover or oil cap then you have faulty rings. This test, if made correctly, can realy pinpoint the exact location or in which cyl. you have troubles avoiding that way the need to disassemble the whole engine (if the problem is in a cyl. head). I may be wrong in something so corrections are welcome.

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post #6 of 10 (permalink) Old Sep 27th, 01, 02:22 PM
 
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Hey you got some nice cars, Wish i could afford three cars also. You must have a really sympathetic wife! my girlfriend would go nuts if I bought three cars! espcially if it was with her money!
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post #7 of 10 (permalink) Old Sep 27th, 01, 05:16 PM Thread Starter
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Thanks

[This message has been edited by Badcaiman (edited 09-27-2001).]
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post #8 of 10 (permalink) Old Sep 27th, 01, 08:29 PM
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Isnt the max differece between cylinders suppost to be around 25 psi max? ran one the other day in school, the results are as follows in order. 145, 162, 167, 164, 162, 162, 170, 175. that is all in the good range, but what about the max difference?
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post #9 of 10 (permalink) Old Sep 28th, 01, 04:21 AM
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78CamaroLT - I'd be just a little concerned about the one cylinder at 145psi since the rest are pretty consistent between 160 and 175. Maybe a recheck would be in order, and a leak down test if it shows the same.

Just my opinion.
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post #10 of 10 (permalink) Old Sep 30th, 01, 04:04 PM
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Make sure you squirt some oil in the cylinder before the test. Thats called doing a wet compression test and gives you more accurate readings.

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