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.
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.
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.
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)
I didn't know mechanical oil gauges used a wire except to light them up in the dark. ?#%$#
Spoon
------------------ "Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut
Originally posted by Spoon: I didn't know mechanical oil gauges used a wire except to light them up in the dark. ?#%$#
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.
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.
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.
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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.
It did seem like there was no way someone could state a given oil pressure to be "ok" across all make and model engines. I assume those numbers are with 5w30 conventional.
[This message has been edited by 2.5 (edited 09-27-2019).]
Originally posted by 2.5: It did seem like there was no way someone could state a given oil pressure to be "ok" across all make and model engines. I assume those numbers are with 5w30 conventional.
don't assume that. This myth has been around for a very long time. Very possible was started w/ some crap that some "old time" Race people used w/ 20w-50. Or even older when Flat Head engines where common and API had SA and SB Oil rating as current engine oils.
All car engine since since at least the 1960's have a OP range like above. Nearly all OP ports are just before or just after the Oil Filter. Both are just downstream of Oil Pump and the Pressure Regulator. (Most Regulators are part of the Oil Pump.) At Idle most Oil pumps generate enough pressure that the Regulator is used all the time to limit system pressure. Some pumps might not make the reg to open at idle but still within the specified range. IOW stays above the low number at idle. Regulators aren't exact but should in upper ½ to ⅓ of the spec.
[This message has been edited by theogre (edited 09-27-2019).]
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
That yes and no... Yes because OE Fiero oil is 5w-30 but No because others are allowed IF outside temp are w/in temp range as publish by API. Same chart covered in my Cave, Oil and Filter (Seems API have moved, likely updated, the chart to add 0w-__. Update: New API chart has 0w.) IOW OP spec should be same for all oils unless weather is too cold.
So... If you live in Nevada etc then likely could run 10w-40 or 20w-50 because won't get freezing weather and see same OP. (Most should never run 20w50 for other reasons. More so w/ newer cars.) If you get freezing weather... 20w-50 won't flow creating higher/lower pressure at minimum. Or even colder then 10w-anything can have same problem. (Oil pump may have a hard time sucking oil thru the pickup tube and screen maybe causing low pressure.)
Colder still is a big part of why Original Mobil 1 and a few other syn oils was made. Was still 10w but didn't have waxes etc that "Dino Oil" had.
Most older cars had 10w-30 or 10w-40 decades ago as OE oil because was hard to impossible to find 5w in the 70's and earlier. Not sure but don't think they made 5w back then. Only in ~ last 10 years is 0w is now made and fairly common. If you lived in Upstate NY and others where outside temp can be 10° to 30° below 0°F in winter... Most cars w/o oil and/or bock heaters won't start because 10w oil was grease or worse.
[This message has been edited by theogre (edited 10-17-2019).]
