165 mercruiser

[doug d]

i just had the head overhauled and i am getting alot of blow-by out of the pcv as well as the dip stick. compression seems low, 105 to 120. did i tighten the valves a bit too much or is the bottom end worn out? it`s the old L 1 straight six. thanks! doug. p.s. the blow by is at about 3000 revs. and very little at idle.

 

[Bondo]

Re: 165 mercruiser

Ayuh,... Welcome Aboard Doug,...

Your compression is in fact quite low,...
And,...
It usually means it's time for a Rebuild to get it back...

You should be seeing 150/ 170psi across the motor,...10/ 15% difference between holes...

 

[JustJason]

Re: 165 mercruiser

you can try backing all the valves off a bit and see if that raises it. If not the only way to confirm it's worn rings is with a leakdown test.