Re: Compression #S what do yous think?
Boat is a 1984 wellcraft Elite 200 with a R drive and 5.7 merc. Engine #6744710 Drive # 6742325. So I did a compression test on my engine today this is what I found ! Cylinder #1 150 #3 135 #5 125 #7 145. #2 150 #4 145 #6 125 #8 145. The engine runs great has all sorts of power But the low readings on 5&6 should I be concerned? And its also odd that the too ajaycent cylinders are both the low comp cylinders any thoughts on this ?
FWIW - #5 & #6 are on opposite sides of the engine, but are in similar positions along the row of cylinders. #3 & #5 are interesting, if that was what you are referring to . . .
The results are indicative of an older marine engine that may need some attention. A cylinder leak test would be a good next step. I would not be surprised to see some valve leakage in that test.
A 'good' compression test will yield +/- 5% from a typical or normal reading, giving you the 10% range, as mentioned. So let's say 145 psi is the 'norm' . . . you would be looking for all cylinders to be in the range of 138 - 152 psi . . . you have 3 cylinders outside of that range.
So, this would be only a 'fair' rating of a test, and probably showing that a valve job or similar engine work was around the corner.
