Compression on 75 merc 2/stroke
Submitted by Lukastoy on Thu, 2016-10-13 17:10
Guys
I have done compression on 2002 outboard before I purchased it was 120,120,120.
Can anyone assist me in confirming these figures sound ok.
i had another member send me reading material from Mercury and they say under 120 can mean damage to motor.
is it normal to reduce more each year from new or would this figure be close to what it was in 2002.
Any comments welcomed if factual ?
North Coast Marine
Posts: 74
Date Joined: 23/05/16
Hey mate, its pretty
Hey mate, its pretty difficult to say whether a specific PSI reading is "good or bad", with a compression test what you are looking for is variences between the cylinders that could indicate bore or piston damage and valve/head gasket issues in 4 strokes. Cranking speed determined by battery health will have more to do with the outright pressure you see than anything else, not to mention different gauges etc. I would have thought 120psi was fine