4.3 mercrusier compression test :(

al0311

Petty Officer 3rd Class
Joined
Jul 29, 2017
Messages
97
Hi guys today I did a compression test. First one I have ever done so I’m not so sure I did it right but it seems pretty staring forward. Only thing I was unsure of was pulling the spark plugs. I pulled one at a time and tested that cylinder with the Remainder spark plugs in place. Also I wasn’t able to get the boat to start so I couldn’t get it at normal opertaing temps to run the test but I did anyway .

1-95
2-60
3-120
5-145
6-90
and the spark plugs had a black soot on them. Sooo needless to say I’m pretty sad with these results. Think the engine is at a lose.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,291
Think the engine is at a lose.

Ayuh,.... it might be a rebuildable core motor, but with those numbers, it ain't a runner,....
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
51,248
Pull all the plugs and retest.

However with those numbers, do a leakdown test to determine if its rings or valves, then rebuild as needed
 
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