Low oil pressure reading (Page 1/2)
Fire hazard SEP 20, 08:15 PM
Well guys I’m at a loss for words. I just got my 87 GT with a 2.8 running a month ago and I’m at school now so I come home on weekends to work on it. ( it’s a very slow process). Anyways, today I decided to put a mechanical oil pressure gauge in because the stock one hasn’t worked since I bought the car. I took out the oil sending unit and installed the plastic hose of the mechanical gauge into the port. There are no leaks or anything but when I start the car the gauge is only reading about 6 psi at idle. When I rev the car up the gauge does increase slightly but then returns to around 6psi. Could this be a faulty gauge? Did I install the gauge in the wrong place? Or could I be looking at some sort of terrible engine problem? Any help is greatly appreciated.
shemdogg SEP 20, 10:00 PM
Its a long run from the motor to the dash, small diameter line will lose some pressure over the distance. Ground one side of the old gauge, if it moves its good. Throw a new sending unit at it, if that doesnt work, then the wire from the sender to the gauge is bad.

shem
Fire hazard SEP 21, 12:30 AM
I took the sending unit out of the car. I connected the new gauge to the block where the sending unit connects. Should I not have done that? I just went out to check the gauge again and now the gauge is reading 0 psi. The engine isn’t making any weird noises or anything so I’m assuming it’s a faulty gauge.
theogre SEP 21, 01:14 AM
Go find a real mechanical gauge. Low pressure will kill the engine.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

Spoon SEP 23, 10:24 PM
I didn't know mechanical oil gauges used a wire except to light them up in the dark. ?#%$#

Spoon

------------------
"Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut

theogre SEP 24, 02:47 PM

quote
Originally posted by Spoon:
I didn't know mechanical oil gauges used a wire except to light them up in the dark. ?#%$#

Spoon

A shop gauge that reads right on the engine OP port.
Not a remote gauge w/ yard(s) long of thin plastic tube sold by most vendors.
Because Thin tube often gets kinked or plugged or the gauge can be bad right out of the box.

Plus you can't just eliminate OE OP sender. You try running w/o fuel pump when FP relay dies.
Both are in parallel to put FP power load between two contacts, not just a extra standby power feed for dead FP relay.
2.5 SEP 25, 10:19 AM
There is an old hear-say stat I have heard, that 10 psi per 1000rpm is all you need. But they never got specific of what weight oil, etc.

Anyone else ever hear that?

[This message has been edited by 2.5 (edited 09-26-2019).]

2.5 SEP 26, 03:52 PM
Sorry I left out an important part, my last post is now edited correct.

"10 psi per 1000rpm"
Lou6t4gto SEP 26, 06:26 PM
10 PSI per thousand rpm is per Smokey Unik. never use nylon line , use 1/8" copper. 10 psi at idle is well...almost OK at best, but SHOULD go to at Least 30 at 1500 rpm. no/low oil pressure "Usually" means very worn Bearings (Main and or rod), sometimes oil pump, but not likely.
theogre SEP 26, 09:13 PM
GM specs are:
V6, VIN-9, 30-45 PSIG
L4, VIN-R, 36-41 PSIG
Oil pressure should stay within the specified range at all RPM. In very cold weather, oil pressure may be a bit higher than normal until the engine warms up a bit.


quote
Originally posted by 2.5:
There is an old hear-say stat I have heard, that 10 psi per 1000 rpm is all you need. But they never got specific of what weight oil, etc.

Anyone else ever hear that?

BS myth push by idiots and believed by fools that don't want to fix or rebuild the engine. Worse is many use this garbage to sell a car w/ fatal problems to first sucker that believes such crap.

Another Big problem is that Some get away w/ "Low pressure" for years because many of them have gauge problems not purely engine problems and these fools think this is normal and safe but often didn't even bother to test what is wrong. Most have to fix/rebuild the engine or simple junk the car when engine is finally dead. Chevy Cavalier Z24 and others had same "Fiero" v6 engine and same problems w/ low OP and many are junked after bottom end fries or engine blows a rod thru the block. Think Fiero is rare now? Try finding anything still on the road w/ same V6.