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M50d2 compression test results

"Maybe. The rule is:

Off by

"Maybe. The rule is:

Off by five, your still alive.
Off by ten, you might win.
Off by 20, your screwed.

We wouldn't let one out of our shop with a 15 psi difference. But, some shops will let them slide up to 20. I would pull the head to see why your off."
 
I completed the test again whe

I completed the test again when the engine was cold.
Slight improvement.
Top 120psi Mid 120psi Bott 135psi
Why the better reading on the cold engine.
 
"Its not really an improvement

"Its not really an improvement. The number will vary depending on the amount of oil in the cylinder, retained heat, etc. The numbers themselves are also unimportant as every gauge will read different. You only need to be concerned with the difference which is substantial. A 15 PSI difference means that you have exceptional wear on two cylinders. There is a reason for that. You really need to determine that reason...Or you can roll the dice, ignore the difference and take your chances. Sloppy techs will tell you that you should be alright at 15. Good ones will tell you you have a problem."
 
"Try using seafoam as directed

"Try using seafoam as directed on can and give the engine a run, recheck the compressions if they are within 10% of each other there is no problem anymore than that is indicating a potential problem. Oh by the way there is good money in rebuilds at a shop."
 
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