Low oil pressure

[OldFred]

Hey all

Today my car started getting really low oil pressure at idle (after it had warmed up, 10 minutes or so), but was fine when I leaned on the gas. I immediately stopped and made sure it wasn't a low oil level problem (it wasn't). Then tonight I had to take it out on a part run for my truck (aren't I lucky? everything breaking at once) and the pressure was considerably worse, and it had dipped even when I was pushing the gas.
It came on so suddenly, but this has to be a oil pump problem right? I thought about a clogged filter but its pretty new so I am doubting that. I fear the ugly alternatives if its not the pump (might be engine overhaul time).

[4kQuad]

my 2.3 starts at about 70 lbs. Run around for a while it will drop to 40 or so sitting at a light.

The oil pump is ran off the timming chain on our rigs, so if the motor is running the pump is turning. Not that it's has to be moving a lot. But it's turning or doing it's pumping cycles.

My haynes says if it get below 30 lbs find out why.....

So how low is it going??

[99GrandAMSE]

... how long ago did you change the oil?

[LargeFish]

Also how many miles on the car? If not the pump it could be rings...

[Rayz]

IMHO I’d replace or test the oil pressure sender before go and put an oil pump in. If it happened all of a sudden it's probably the sender. The oil pump or engine bearing seem to be a more gradual decline.

[OldFred]

It is a high mileage engine, so I do fear that its going to be something a bit more discouraging than just the oil pump, but I'm hoping!

If it was the sender unit would't the gauge just stay stuck in the same position? Mine still registers changes.

[Rayz]

If it was the sender unit would't the gauge just stay stuck in the same position? Mine still registers changes.

on various cars I had them go both ways I once replaced a oil pump just to find out the sender was bad and reading about 20 psi. lower then actual pressure. I'd hook-up a mechancial gage to check before I'd change an oil pump again.

[4kQuad]

How low does the gauage get to on pressure??

[OldFred]

All the way down to pretty much nil.

Just barely sits above the zero when im idling.

Today I started it up just to move it into the garage so Icould get under it and the pressure was fine for the 10 minutes I ran it.

The last oil change was done about 1500 miles ago. I drained the oil and will put on a new filter right now (in case the old one was plugged and was the culprit). Im also going to drop the oil pan so Ican take a look at the pump and the screen. Where is the transaxle bellhouse cover?? I'm suppose to take it off to get the pan off apparently but have no idea what one looks like or where it is. Looking around the transaxle has not led me to any great revelations.

Any help?

Thanks guys

[LargeFish]

RAYZ right, could be the sender especially if it's reading low and running pretty well. Maybe see if you can test it with a mechanical pressure gague?

[99GrandAMSE]

Originally posted by LargeFish
RAYZ right, could be the sender especially if it's reading low and running pretty well. Maybe see if you can test it with a mechanical pressure gague?

:agree: ... my thought about the oil was simply that sometime oil, over time and use, will loose viscosity to the point where oil pressure will suffer (it used to happen to my JEEP) :(

[LargeFish]

It's usually hard to keep a Quad with low oil pressure running, tends to make the car stall at idle so if the idle is solid I would question the reading. YMMV.

[OldFred]

Ok, that makes sense.

Where does the mech. gauge hook up to for me to take my reading?

[LargeFish]

OK, I see from your other post that you have a Haynes, check there. Also maybe run a search as I remember discussion about it before, but not sure if it was since the board move. I'll also haul out my books when I move to another workstation and see what I can find.

[OldFred]

Thanks Fish

I'll comb the Haynes, see what I come up with

[LargeFish]

1-6A710 in the '92 shop manual covers it. Remove cooling fan connector. Remove oil filter. Install J 20587-C Oil pressure tester. Start engine. Thought there was somewhere else you could test it... Where the sensor is maybe?

[OldFred]

So it just goes in where the filter screws in?

[LargeFish]

Yep, if you have a GM tester that's where it goes...

[mikem220153]

I agree with checkng the sending unit first.

On most engines, when you hook up a direct reading gage, it goes where the oil pressure sender is installed.

[matts]

if it has very many miles on it it could be cam bearings. my truck has 208000 miles on it and my guage says i have no oil pressure. i checked the sending unit, gauge, and i replaced the oil pump. still notta, i talked to a mechanic and he said that the cam bearings were probably wore out and the sending unit wasn't working right because of it. he told me that i didn't have a loss of power and my truck was still running right that i shouldn't worry about it, but he knows that i'm having another engine built right now. so it don't really matter if it croaks or not. but i hope its something simple

[4kQuad]

Well, its been a few days. Just wondering how things are going with the project.

Like others I'm betting on the censor. You said it gets to Nil. Well, if it's been saying that and you have still driven for more than 3 to 5 miles. It must be the censor or it would have locked up and died. At least thats my logic.

[OldFred]

Where is the sender unit on my car located?

I cleaned the pick-up and screen and changed filters ('case it was plugged) and still get low pressure.

Ill buy a gauge and check it manually as soon as I can figure out where the sending unit is.

[mikem220153]

Here is a picture of the sender and it's approximate locations.

[4kQuad]

Yep just to the right of the power strearing pully and above the Therm-stat. It should screw out just pull the wires first. May also want to pull the ground on the battery first. Might not be needed but whith every thing computer driven, I just feel better taking the extra few seconds.

Good Luck.

[OldFred]

Perfect, haven't had a chance to check for it yet but should have no problems now thanks to your help.

Thanks for the patience guys.