oil pressure releif valve---please help

[sawilliams]

my oil pressure releif valve is half there--the outer part only--and so far impossible to extract. im thinking of running without it. my question is---is it for smog only????i understand crankcase pressure, but is it that critical for a daily driver. thanks all. steve:ermm:

[Gav240z]

If your talking about the one that goes from the engine block and to the carbies it's there because u will end up making the inside of your engine clogged up with sluggy oil.

Well so I believe.

[beandip]

Gav240 is talking about the PCV valve . sawilliams describe what you are referring to as a oil pressure relief valve , are you referring to the pressure relief in the oil pump or at the oil filter???

[sawilliams]

beandip---im talking about the 1/2 inch size housing--that houses the ball-- that is within the diameter of the oil filter. oil is going around it at all times and then it opens at higher oil pressure. im thinking it opens a passage way right back into the block. so why not run the oil through there at all times. im talking motorwise functionality----not what it may or may not do for all the sensors and stuff for smog. i guess im asking ---why do z's have this there. its my first encounter with one. please help. thanks. steve:classic:

[Bambikiller240]

I was under the impression that it is a pressure relief valve so that if the oil filter gets clogged, there is a path for oil to return to the engine block and continue a flow of oil (and oil pressure)throughout the block.

Anyone want to correct me if I'm wrong? Don't have my manuals here to look through, but that is my recollection of the purpose for the spring-loaded check ball at the oil filter mounting.

[MAYHEM]

Originally posted by BambiKiller240

I was under the impression that it is a pressure relief valve so that if the oil filter gets clogged, there is a path for oil to return to the engine block and continue a flow of oil (and oil pressure)throughout the block.

Anyone want to correct me if I'm wrong? Don't have my manuals here to look through, but that is my recollection of the purpose for the spring-loaded check ball at the oil filter mounting.

I beleive your right BambiKiller240 . My sbc has the same type of set up. I removed mine and tapped the hole and inserted a plug. This forces oil thru the filter period. And 90% of car crafter that do this mod, keep up on there oil and filter changes. But be warned ....... don't rev the motor cold, it could split the oil filter case. But we don't do that .... right

[sawilliams]

thanks guys for your replys. its just that i cant get out the busted one that is in there now( only the housing is left) and i want to run it for a little while before i get into a whole engine rebuild. at that point i can drive it out from the inside. i just didnt want to blow it up. MAYHEM---is the oil filter case the exterior of the oil filter or the part of the block where the oil filter seats. -----and reving it cold ---is it common or rare for it to blow. FYI you can buy 1/2 and 3/4 inch easy outs at a plumbing store ( i did ) that didnt get it out----so i think ill wait..........THANKS AGAIN EVERYONE. STEVE

[Bambikiller240]

Originally posted by sawilliams

MAYHEM---is the oil filter case the exterior of the oil filter or the part of the block where the oil filter seats. -----and reving it cold ---is it common or rare for it to blow.

MAYHEM is referring to the oil filter itself. If the presure relief is eliminated (plugged or capped off) and you rev a cold engine, that thick oil and the increased pressure from high RPM operation WILL split the filter sometimes. There ARE reasons for the pressure relief valve to be there! If you plug the relief valve, don't rev the engine cold. It only takes a few minutes to warm the engine properly. Why take ANY chances?

FWIW

[memoryz]

on aircraft the oil pressure releif valve is to set the oil pressure to a fixed value and i assume it's function is the same on this engine. the pressure builds up to a certain amount overpowering the spring behind that little ball and allowing the oil to bypass! if the spring is or has been weakend by heat or what ever, your oil pressre would be low?????? :cross-eye

[jaltman]

Please allow me to revive this thread. I have noticed that my oil filter has stayed empty on the last change and I would suppose from this thread that means my pressure relief valve is stuck open. Its not exactly obvious to me how the pressure relief valve is in the oil filter area or how to remove it. Does anyone have a picture or can, perhaps, describe it for me so I can try and pry it out and examine?

Edit, btw, oil pressure is good, the top end is nice and wet with oil, all indications are that oil is getting every where it needs to be.

Edited June 8, 2014 by jaltman

[Zed Head]

It's the thing that holds the big ball bearing, under the filter. Image of it removed, way below. BUT, your problem might be in the filter itself.

Anti-Drainback Valve. Some oil filter mountings may allow oil to drain out of the filter through the oil pump when the engine is stopped. When the engine is next started, oil must refill the filter before full oil pressure reaches the engine. The anti-drainback valve, included in the filter when required, prevents oil from draining out of the filter. This anti-drainback valve is actually a rubber flap that covers the inside of the inlet holes of the filter. When the oil pump starts pumping oil, the pressure will unseat the flap. The purpose of this valve is to keep the oil filter filled at all times, so when the engine is started there will be an almost instantaneous supply of oil to the engine.

FAQs| FRAM

Datsun 240Z Oil Pressure Relief Valve, 260Z 280Z 280ZX

[jaltman]

Thanks for the quick reply. I have been using Mobil 1 filters, which do have the flappy valve inside the inlet holes. Of course, that doesn't mean they work. My concern was heightened by the way it looked like the filter was dry as opposed to recently drained. Of course this could mean its the Mobil 1 filter that had too stiff a flappy thing. OTOH, for $4.76 I can well afford to just replace the pressure relief valve.