yamaha 2007 150 four stroke high engine oil pressure !!! help !!!

Joined
Feb 17, 2011
Messages
3
hello all

have a rebuilt power head that was just installed went to start up for the first time and it blew through the oil filter seal.

-I confirmed through sender and my own gauge that the oil pressure is in excess of 120 psi.

-oil is at normal level and I have tried three new oil filters.

-I have replaced the oil pump and relief valve to no avail.
engine runs rough currently but I believe it could be due to throttle position.

-I have checked compression on all 4 cylinders and all over 175 psi.
also not that it matters but there is also a considerable amount of oscillation on manual gauge almost like cylinder compression when reading lube pressure.

I am at a loss. third times a charm with the relief valve or tear it down to the block for a hot tanking?

I have inquired to some experienced minds and no one seems to know.

for whats its worth the engine cranks over by hand easily so it leads me to believe it is not due to some blocked bearing.

the only thing I cannot reconcile is whether or not I have a blocked passage or exhaust gasses charging the lube side of things i.e. head gasket, exhaust gasket, valve seal.

I am clutching at straws hoping a teardown need not take place.

to all those brave enough constructive suggestions welcome. I am stranded for now until I can resolve this.
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: yamaha 2007 150 four stroke high engine oil pressure !!! help !!!

for whats its worth the engine cranks over by hand easily so it leads me to believe it is not due to some blocked bearing.
Having a bearing blocking an oil hole, will NOT make the engine turn harder. It will only stop the oil from circulating through part of the engine and will cause high oil pressure.
The only way to check is to disassemble and inspecting every bearing.
 
Joined
Feb 17, 2011
Messages
3
Re: yamaha 2007 150 four stroke high engine oil pressure !!! help !!!

do you believe this to be the case?. why would the pressure be excessively is it that the engine is overflowing the relief valve fully open because of the blocked bearing and therefore causing the over pressurization??
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: yamaha 2007 150 four stroke high engine oil pressure !!! help !!!

The thing that controls oil pressure is the gaps between the main and cam bearings, not the oil pressure relief valve. The relief valve may be set at 120 psi, and that is why you don't have even more. A passage is plugged up, rather it's a gasket, or bearings in backwards and blocking the holes or whatever, it has to come apart carefully and everything checked on the way.
I do not have an oil flow diagram for that engine, one may not even exist. But I do know how they are supposed to work.
 

fgrzanov

Recruit
Joined
Apr 6, 2024
Messages
1
hello all

have a rebuilt power head that was just installed went to start up for the first time and it blew through the oil filter seal.

-I confirmed through sender and my own gauge that the oil pressure is in excess of 120 psi.

-oil is at normal level and I have tried three new oil filters.

-I have replaced the oil pump and relief valve to no avail.
engine runs rough currently but I believe it could be due to throttle position.

-I have checked compression on all 4 cylinders and all over 175 psi.
also not that it matters but there is also a considerable amount of oscillation on manual gauge almost like cylinder compression when reading lube pressure.

I am at a loss. third times a charm with the relief valve or tear it down to the block for a hot tanking?

I have inquired to some experienced minds and no one seems to know.

for whats its worth the engine cranks over by hand easily so it leads me to believe it is not due to some blocked bearing.

the only thing I cannot reconcile is whether or not I have a blocked passage or exhaust gasses charging the lube side of things i.e. head gasket, exhaust gasket, valve seal.

I am clutching at straws hoping a teardown need not take place.

to all those brave enough constructive suggestions welcome. I am stranded for now until I can resolve this.
did you ever figure it out ? I have a same problem
 

cyclops222

Lieutenant Commander
Joined
Mar 21, 2024
Messages
1,640
This problem occurred ...AFTER ... the rebuild ? Somebody did something wrong.
 
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