Thread: Low Oil Pressure?!?!

Recently after changing my oil, the oil pressure light would come on after warming the car up and being at low idle. I was thinking that maybe the pressure switch may have gotten a piece of junk stuck in the opening, so I got a pressure gauge and hooked it up.

The result: Almost no pressure reading at idle, but it'll build up to over 50psi when I rev it.

Any ideas as to where I may be losing the pressure at idle??
intake and head gaskets are still factory original, but I don't see any crossover between oil and coolant, nor do I see a significant oil leak. I'm almost certain that I have leaky LIM's. Could that contribute any to my problem?

I know on my gauge Oil Pressure gauge, I lose pressure when I am not on the gas. But I dont bottom out to 0. I might go from 75psi down to 50psi roughly, but that is cause the engine is not revving and building up pressure.

As for your issue, its hard to say. Have you checked your oil level in your car since you filled it? And did you put back on the oil cap on the valve cover? I know these dump questions, but ones that have to be ask. And you have not seen any oil leaking from your new filter or anything?

Just some thoughts.

Went out and double checked all of those and they are fine. I'm thinking it may be the bypass valve or oil pump. The pressure comes up from just above 0 after about 1300 RPM and quickly goes just above 50 psi, but it never goes higher than that no matter how hard I hit the throttle. Is it possible I have it wired in a bad spot? I have the power hooked to my ignition and the ground running to the dash support. I just hope it's something fairly inexpensive and easy to replace!

The hook up of the gauge sounds correct. When I tapped mine, I connected to probably same pink wire inside that cubbyhole and ran one line up to the pod and tapped all my gauges into it. And I tapped my negative to the bolt that connects to the E Brake pedal. Its doubtful its an electrical issue, cause if it was, it would read either nothing or pegged to the max.

Mine is pegged to the max cause I dont have the correct FULL Sweep sender unit and the wiring that goes along with it. But for $125 bucks it can wait a little bit. Did you buy your gauge new? And what brand is it etc.

Pretty UNcommon for one of our pumps to go out or bad. Only time I have seen one on its way out was from the owner not changing the oil and filter like they should, and the front aluminum cover, which the pump rides in, was pretty destroyed.

My oil pressure reads 50 on the dot on a cold start, and will go down to around 20/25 when its warm and I'm not on the throttle.

Not all after market sending units are the same. Last one I had read 60 no matter what, warm...cold...at idle, driving down the high way. It was leaking, so replaced it, now this one makes the gauge move.

You have oil pressure at start up...so your pump is pumping...

I believe your problem lies in either not having enough oil in your motor, or your sending unit its self for your gauge. You said your oil light came on...so you have your stock sender still plumbed in?

~F~

I had the stock sender still attached until I replaced it with the sending unit for the gauge. My first thought was that the stock sending unit had failed or gotten trash in it, but with the gauge reading super low, as well, I'm thinking I have an issue elsewhere.

My buddy borrowed the gauge temporarily to make sure his 260Z was still holding pressure and it read out what seemed to be good pressure. 15-20 at idle and 50-60 with a gentle rev.

It's a Faze gauge and it was purchased brand new in a sealed box, so I know no one messed with it previously.

Is there possibly a way to check the bypass valve without removing the filter housing?

Originally Posted by DanGTP

Is there possibly a way to check the bypass valve without removing the filter housing?

Not that I am aware of. And you would need a new gasket for the oil filter housing as well. I installed the ZZP oil flow modification some time ago, so its not hard work, the bolts are a bit tedious to get to but not impossible.

After installing the ZZP mod I dont recall ever seeing my oil pressure below 50 psi at idle fully warmed up. But as far as being able to check that without pulling off the filter house, I dont think there is a way to do so.

i went ahead and ordered the oil flow kit from ZZP the other day and and expecting it soon. I'll get it on the car as soon as I have a few hours of free time.

Well... Bad news. I put in the new bypass valve and still have crappy pressure. It does rest a bit higher and peak a bit higher, but not enough to call it good pressure. I'm looking at like 5-10 up to like 60ish now.

Could the leaking intake gaskets be a cause? I'm not getting any cross contamination between oil and coolant. So I'm pretty sure it's not a head gasket.

Oil pump maybe?? What are the symptoms of that?

I dont think I have ever heard of an oil pump failure on our cars. Not saying it hasnt happened, just never heard of it. Any chance there is a problem with the oil filter itself?

The only other thing I can think of would be some type of blockage in the oil passages.

I went out earlier this evening and got a cheap filter from work to try. I'll see about putting it on tomorrow and report back the results.

Low oil pressure could be a sign of a worn bearings, cause when there is room, they just bleed pressure off and it doesn't reach the higher parts of the motor....

Pull the front valve cover and run the engine at idle, there should be oil flowing over the rockers, from the intake side towards the radiator, may not be a lot. but, if the rockers are running dry you may have a bearing or pump problem problem( you may be able to just remove the oil cap and see)

Hopefully it isn't anything major

I'll change the filter tomorrow and, if things don't change, I'll check the rockers.

You should be able to watch em though the oil fill, just use a flashlight and hope for the best

Hmmmmmmmm. 1am diagnostics coming up...

Well... I fired it up and pulled the cap off. I was unable to see any oil squirting, but since I don't really know exactly where to look, that may not be a definite conclusion. There was visible oil puddled around the head bolt, however.

I killed it and touched both of the exposed rockers and neither felt very wet with oil. Should it be squirting immediately after a cold start-up, or will it take a few minutes? I only ran the car a minute or so.

Now that I think about it, I recall at an earlier time (before the oil change and this problem) seeing plenty of oil when I opened the cap. It's funny that this problem did not seem to appear until after this recent oil change. Could I have possibly gotten a piece of sludge stuck in one of the oil passages? I did run a SMALL amount of seafoam through the crank case 10 minutes before changing the oil. Also, I switched from Mobil 1 Extended Performance 10W-30 to Royal Purple 10W-30. Is there enough of a difference between the two to bring an issue like this to a head?

You may have dislodged something with the seafoam, but the pressure at the filter assembly(where I assume your pressure reading is coming from) would be high, cause it would have no where to go

Just out of curiosity, did you change your oil filter? If so I assume that there was no change. What kind of oil filter are you using?

FWIW, mine hangs at about 50 till warmup, then drops to 30 at idle and about 70 at high RPM and thats with no mods to the oil system. I am running both the light on the dash and a guage, so if you want to swing by sometime, I can show you how to run them both at the same time.

webracin

I just got through changing the filter just to see. Nothing changed. I was using an AC Delco filter, but the one I went and got last night was the Valucraft filter that Autozone carries since it was the cheapest. It's only for testing purposes, though. I will put the AC back on tonight or tomorrow since changing the filter didn't help any.

What's left, now?? Drop the pan and check if the pump screen is clogged? I did notice when I removed the first filter, that there were some tiny bubbles floating at the top of it (I had to pull the car into the garage). Any indication as to a specific problem?

I would imagine it would have to be either the pump or the pickup. I believe the oil goes from the pickup, to the pump then to the filter and the port is measuring the pressure as it leaves the filter. So if you have low oil pressure there then it has to be before it gets to the engine.