compression test numbers...i hope we did the test wrong... :/
12-28-2005, 04:22 PM
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compression test numbers...i hope we did the test wrong... :/
Ok, so we just performed a compression test on my '94 gsr and the results are...less than desirable. My results were the following (starting from the distributor side):
150
200
125
170
I really don't understand this...I mean, I performed this test like 6 months ago and had much more solid numbers...also, how much does it matter whether the car is warm or not? i mean, i haven't driven the car in like 2 weeks and we didn't run the car at all before the test because we couldn't get it started...would it be a lot different if the car had been at operating temp shortly beforehand? what do these low numbers indicate? thanks...
150
200
125
170
I really don't understand this...I mean, I performed this test like 6 months ago and had much more solid numbers...also, how much does it matter whether the car is warm or not? i mean, i haven't driven the car in like 2 weeks and we didn't run the car at all before the test because we couldn't get it started...would it be a lot different if the car had been at operating temp shortly beforehand? what do these low numbers indicate? thanks...
Last edited by R_Squared; 12-28-2005 at 04:44 PM.
12-28-2005, 04:38 PM
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well ur car being heated up COULD mess them up. im not sure. do it again with it warmed up
or ur piston rings r leaking or ur valves r leaking. u need to do a wet compression test to see if it is either rings or valves. im not sure wat normal compression is for the gsr but it may be 220...the LS is 180...
for a wet compression test just put 2 drops of oil in the cylinder, let it soak for a couple min then do the same thing as the dry test. err actually wait till u do the dry test again properly
or ur piston rings r leaking or ur valves r leaking. u need to do a wet compression test to see if it is either rings or valves. im not sure wat normal compression is for the gsr but it may be 220...the LS is 180...
for a wet compression test just put 2 drops of oil in the cylinder, let it soak for a couple min then do the same thing as the dry test. err actually wait till u do the dry test again properly
12-28-2005, 04:43 PM
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i believe 200 psi is what the B18C should be sitting at. my buddy told me similar directions for a "wet compression test" where you put 2 capfuls of oil into the cylinder with the lowest compression (from the dry test) crank the car to let the oil settle, and then check the compression. he said if the compression number goes up then there is a problem with the rings and if the compression number goes down there is a problem with the cylinder head...but like i said, i did the compression test when the car was completely cold so maybe that's make a big difference? i will probably try and test it again tomorrow.
12-28-2005, 05:09 PM
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If the engine is warm, everything will seal better due to expansion. Warm the car up, and make sure you are at WOT during the test. What alarms me is the large difference in numbers between the cylinders....but retest and give us the results.
12-28-2005, 05:14 PM
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just do another dry test, make sure its 100% warmed up (doesnt take that long to do 
) but 2 capfuls for the wet? 
wat size cap? all u need is a couple of drops...trust me...for fun i put uhh lets say 20drops from those little oil dripper things and now the car has a rough idle (in a shop car in my rop class) and needs new spark plugs...o and oil was leaking onto the head...so yea ONLY do 2 drops. and i think he meant valves instead of cylinder head...
) but 2 capfuls for the wet? wat size cap? all u need is a couple of drops...trust me...for fun i put uhh lets say 20drops from those little oil dripper things and now the car has a rough idle (in a shop car in my rop class) and needs new spark plugs...o and oil was leaking onto the head...so yea ONLY do 2 drops. and i think he meant valves instead of cylinder head...
