M50d2 compression test results

Author Message   Ray Gleeson New member Username: raym Post Number: 3 Registered: 10-2009 Posted on Friday, November 20, 2009 - 12:03 pm:    top 115 psi mid 115psi Bottom 130psi Is this range ok or do i have a problem   Tohatsu Guru Senior Member Username: tohatsu_guru Post Number: 1059 Registered: 06-2007 Posted on Friday, November 20, 2009 - 12:24 pm:    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.   Ray Gleeson Member Username: raym Post Number: 4 Registered: 10-2009 Posted on Saturday, November 21, 2009 - 07:47 am:    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.   Tohatsu Guru Senior Member Username: tohatsu_guru Post Number: 1061 Registered: 06-2007 Posted on Saturday, November 21, 2009 - 09:11 am:    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.   jamie campbell Advanced Member Username: outboard_doctor Post Number: 796 Registered: 02-2009 Posted on Monday, November 23, 2009 - 07:53 pm:    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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