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Old 05-22-2022, 04:02 PM   #1
bsampson
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Join Date: Jul 2012
Location: Central IL
Posts: 63
Compression Test on 200k LQ4 - Question on Results

I have a 200k mile LQ4. I have it on an engine stand, and am planning to put in a new cam, lifters, lifter seals, timing set, oil pump, and rear and front main seals.

The engine has been sitting for over a year. Old oil is still in the pan.

I wasn't going to pull the heads, but after doing a compression test, I got higher numbers than expected. The compression tester is a new, $25 amazon tester.

Front of Engine
(1) 225 (2) 235
(3) 235 (4) 225
(5) 235 (6) 60 (260 after 1Tbs oil)
(7) 235 (8) 230

On cylinder 6, I test multiple times. It did hold pressure fine, just wouldn't pump up well. I went to lunch, and came back and it held 100psi for probably 45minutes. In subsequent tests, it seemed to increase and got up to around 150 psi. Once I squirt a little motor oil in the cylinder, it quickly went up to 260 psi. And held.

Question 1 - Does the high pressure mean I have a crappy gauge, or lots of carbon buildup?
Question 2 - Should I be concerned with cylinder 6?
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