PCM 351 low compression one cylinder

seaweaver

Recruit
Joined
Aug 20, 2004
Messages
2
Hell all
I gotta 351 yesterday in an 85 Ski Supreme .The guy bought it from some kids (470hrs) and said they had screwed the wiring (fixed) and had trash in the tank. Oil looked like junk so he changed it (syn) When I saw this 3 days ago the oil looked high and caramel (not milk choc) Yesterday I picked it up and we ran it for a few minutes till it looked like it was getting hot. I bought it (price was very right).
Got it home and pulled thermostat and ran for 20 min on jerrycan fuel. No issues I could detect. Oil still look the same caramel and high.. but clear to read markings. Today I plan to pull plugs and inspect and check compression.

Today on a cold engine I got 140-45 psi on all but one cylinder. that cylinder is reading 120... and with a dose of oil it jumps to 145.
What to do? Run and let it warm very well prior to use? Drop the pan, pull the head and try to work that one cylinder?
This is my first inboard.
Thanks
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,994
Ayuh,..... Welcome Aboard,..... Which cylinder,..??

Did ya do a leak-down test,..??
 
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