Oil relief valve causing low oil pressure?

[decathect]

I have heard of this valve failing, causing HIGH oil pressure, but can failure cause low oil pressure? I have low oil pressure primarily when the car is very warm, at idle. Is it even worth looking at?

Does anyone know more about precisely when this valve should be open, and when it should be closed?

 

[Bud92gsx]

Low oil pressure whe warm at idle is normal...I mean not like minimal but under the little line? Your not on the throttle, the oil pressure is going to drop..

 

[decathect]

Right. Its too low. Its causing my car to register knock due to extra engine noise from low oil pressure.

I'm not asking for input on whether or not I have low oil pressure, at this point I'm wondering if it is the relief valve COULD be causing this.

 

[BogusSVO]

if the relife spring is weak or broken it will allow the oil pressure to bleed off before it is needed too

 

[decathect]

Under normal operation, when SHOULD that valve open?

 

[Bud92gsx]

When there is too much pressure in the crank case, the pcv valve will releive pressure..Unscrew it and clean it out with brake clean or something..

I wouldnt think that it's your oil pump, cause if that was the case you probly wouldnt have oil pressure in the 1st place..Then boom..

 

[decathect]

I dont think you understand the relief valve. It is separate from the PCV system.

 

[turboglenn]

I'm pretty sure the reliefe valve is supposed to open at 60psi, the general rule of thumb for oil pressure is 10psi for every 1000 RPM of engine speed...I.E. at 3500 you should have at least 35psi of oil pressure (or more) With balace shafts removed you usually have to port the OFH releif valve to bring it back under control...never heard of one causein low pressure, you might want to check the pump, bearing cleanrnaces etc...if you really think it's too low.

The stock gauge is junk, it to me is only to tell if i have pressure or not...definately not for an accurate reading. Stock my OEM gauge would sit at the bottom line at idle then hover about 3/4 the way up at highway speeds. after putting in a real guage it's apparent that the OEM unit is pure junk.

 

[bling5tatus]

WHAT?!? PCV valve does NOT relieve extra oil pressure. It relieves AIR pressure from blow by... and this by nature has oil in it...

I'd check your oil pump sprocket/shaft for play... or possibly run a thicker oil than 10w30 if you're using an old beat oil pump.

Glenn - did you use electrical oil pump gauge or mechanical to replace the stock one? I would assume mechanical.

 

[dsmfa9nutter]

^Probably electrical. Mechanical oil pressure gauges are dangerous as hell and aren't legal at any track.

OP, get a real oil pressure gauge. I run around 30psi at 1krpm to over 110 when cold and then back to around 90 at wot when warm. This is with BSE and no relief valve porting.

 

[lacroixdp]

These oil pumps are extremely robust... I would not suspect that as a failure, at least not at first. The relief valve would have to be stuck in the open position to cause this problem... I doubt that's the case as well. Most of the time, they get stuck in the completely closed position, not vice versa. Get a oil pressure gauge from HF and check it at the head. If it really is low, then you can unbolt that relief valve on your oil housing and check it if you'd like. If you're getting knocking, it's possible you've spun a bearing or you just have plain old excessive bearing play causing your low pressure. You could easily check this by dropping your pan and removing a main. If your gear bolt for the oil pump fell off, it would cause you to lose massive amounts of oil, which obviously would affect your pressure. Good luck!

 

[decathect]

thank you for the helpful responses. I'm a bit mystified myself as to the cause of the low oil pressure. I am going to install a oil psi gauge soon to find out, but i'm 99.9% certain low oil pressure is causing the problem i'm having, due to the nature of the problem. I'll post up once I get oil pressure readings.

 

[decathect]

Alright, I was wrong! Dangit, that never happens!

My stock oil sensor or gauge must be bad, because I hooked up a digital oil pressure gauge, and my readings are as follows:

Warm idle: 15-18 psi
Cruising at 3k RPM: 75 psi
Cold idle: 25-30
Cold, cruising at 3k RPM: ~90 psi

Seems alright to me? Back to the drawing board on this phantom knock thing. Its weird, I get knock when the car is warm, oil pressure is lowest, and I do like a 1st or 2nd gear pull. Once the oil pressure rises up, it stops knocking. Any suggestions on why this might be happening?

 

[lacroixdp]

Take the readings from the head. Those are from the OFH.

 

[decathect]

Yes, those readings are from the OFH, that's also where the stock sensor is. I've never been told to hook my gauge up to the head. Isn't there a restrictor that limits oil pressure to the head to be like 20-30 psi? Or are you saying I should just see what it is at the head, to determine if the head is getting enough oil? I'm unsure why you want me to do this.

note, by knocking, i mean my logger is registering knock. Not that I can hear an audible knock sound when I rev the engine. I know what a spun bearing sounds like.