Oil Pressure Issue

[Steve_D]

Your thoughts please on an oil pressure issue.
Subaru Legacy 2.5 N/A 1997 engine.

On cold start and idle it takes the (aftermarket) oil pressure gauge to the 80psi endstop. (On Monday I will try a different gauge and sender).

Oil is leaking past the front camshaft oil seals.

Initial thought was that the pressure relief valve is stuck closed but I’ve just found the specs which say ‘Hot engine 600rpm 14psi, 5000rpm 43psi, pressure relief valve 85psi’ so on that basis the relief valve may be OK but that does not answer why it is so high.

At present there is no coolant in so I can’t run it up to temp.

Being as hot idle should be >14psi I would not expect it to be 80+ at cold or does someone know otherwise.

Are there any known issues with, say, head gasket failure to the oil passage?


Steve

[stevieturbo]

Steve_D said:

Your thoughts please on an oil pressure issue.
Subaru Legacy 2.5 N/A 1997 engine.

On cold start and idle it takes the (aftermarket) oil pressure gauge to the 80psi endstop. (On Monday I will try a different gauge and sender).

Oil is leaking past the front camshaft oil seals.

Initial thought was that the pressure relief valve is stuck closed but I’ve just found the specs which say ‘Hot engine 600rpm 14psi, 5000rpm 43psi, pressure relief valve 85psi’ so on that basis the relief valve may be OK but that does not answer why it is so high.

At present there is no coolant in so I can’t run it up to temp.

Being as hot idle should be >14psi I would not expect it to be 80+ at cold or does someone know otherwise.

Are there any known issues with, say, head gasket failure to the oil passage?


Steve

So there arent actually any problems, and you havent run it hot yet as there is no water in it ? SO dont really know what oil pressure you will see ?

And as always....some history ?

[PaulKemp]

Pressure will always be higher cold than hot
Head gasket leak is unlikely to produce oil pressure issues if it did you'd be seeing exhaust smoke

[Steve_D]

I hung a different gauge and sender on it yesterday which gave a figure of 95psi.
Fitted a different oil filter in case the one fitted (which was new) was wrong or defective.
Put coolant in but have not run it again yet.

Steve

[FordPrefect56]

It's really only the pressure relief valve and grade of oil which can affect this so it's almost certainly the relief valve sticking.

[stevieturbo]

Without any past history, or test the gauge is accurate, or signs of an actual problem...I think there is no real problem here at all.

[FordPrefect56]

stevieturbo said:

Without any past history, or test the gauge is accurate, or signs of an actual problem...I think there is no real problem here at all.

Until the hot oil pressure is known I agree. Some engines don't moderate the cold pressure as well as others so I'll rephrase what I said above. "IF" the oil grade is correct and "IF" the cold pressure is abnormal for this type of engine on that grade of oil then it's the pressure relief valve that is likely the cause. If the hot pressure is within spec then don't worry. As for leaking from the cam seals, there's no oil pressure there anyway so this is nothing to do with the pump.

[Steve_D]

Right, stand down chaps, panic over.
Got the engine up to temp and the pressure came down and settled at 20psi on idle and goes nicely up with the revs.

Thanks for all your thoughts and replies.

All I have to do now is work out why the coolant is reluctant to circulate to both the rad and the heater.
Kitcars, what fun.

Steve

[stevieturbo]

Steve_D said:

Right, stand down chaps, panic over.
Got the engine up to temp and the pressure came down and settled at 20psi on idle and goes nicely up with the revs.

Thanks for all your thoughts and replies.

All I have to do now is work out why the coolant is reluctant to circulate to both the rad and the heater.
Kitcars, what fun.

Steve

Subaru engines can be very difficult to fill. Do it veeryyyyy slowly, from dry and have the correct quantity of water so you know it has taken all it is supposed to.

If need be remove the bleed pipe off the top of the rad, or the top hose during initial fill as this will help expel air.
But patience is the key.

[Steve_D]

stevieturbo said:

Subaru engines can be very difficult to fill. Do it veeryyyyy slowly, from dry and have the correct quantity of water so you know it has taken all it is supposed to.

If need be remove the bleed pipe off the top of the rad, or the top hose during initial fill as this will help expel air.
But patience is the key.

The engine is in the rear of a kitcar so had no idea how much it would take. Took almost a whole day to fill and I'm not convinced it is done yet. Certainly made plenty of gurgling noises along the way.

Steve

[stevieturbo]

Steve_D said:

The engine is in the rear of a kitcar so had no idea how much it would take. Took almost a whole day to fill and I'm not convinced it is done yet. Certainly made plenty of gurgling noises along the way.

Steve

Anywhere there may be air trapped, if you can bleed the system at those points. Either via installing a bleed screw into a pipe for example or undoing a hose for a time would be helpful.
And better still any spots like this if they can then have a bleed hose routed to a remote header tank all the better so it's always self bleeding.

Of course there is also the chance continual air lock problems are down to blown head gaskets