An odd thing happened on the way to work today...

I was driving a long and I noticed the oil pressure was steadily dropping. While cruising it was at 60psi, at idle around 30. After awhile I noticed the idle pressure was dropping to around 25 or so and cruising to about 55+/-. As I was nearing work the needle was no longer holding steady. At idle it was fluctuating from 15-25, but it held steady at 45-50.

I changed my oil this weekend and used a Purolator filter instead of the usual AC Delco, so I figured that it was probably the culprit and that I was leaking oil. When I got into work, I checked and there's not a drop of oil on the outside of the filter or the drain plug. I let it sit for awhile and nothing -- no leaks. I popped the hood, checked the oil and the level is in operating range -- doesn't even look low. I smelled the oil on the stick and could smell no coolant.

I'm thinking it could be a sending unit, but while I was driving the engine was running hot -- very hot -- and pinging. So I'm thinking it could be something else. I just had the heads worked on, so I doubt the gasket is to blame (plus no coolant in oil that I could see or smell -- gonna check the radiator for oil next).

I've troubleshooted everything I could think of, but I know I'm missing some stuff. Can anyone lend a hand? Thanks.

 

how hot is hot? An oiling problem will cause an engine to overheat from excess friction. Also excessive heat will cause thinning of teh oil and make the pressure drop because teh decreased viscosity makes it easier to circulate. Id hook an actual oil pressure gauge to get an accurate reading on the pressure. The dash one isnt to accurate.

 

Thanks. I hadn't considered the heat into the equation. It was pretty hot out today and the car was running close to the red. The coolant level is fine, but it's old, so maybe I'll flush it out and refill. Hopefully it's just the outside heat that's causing the oil to thin.

But I'd still like to get an accurate gauge for the oil pressure. Should I just swap out the factory gauge and install a new one inside, or do they have one that can sit in the engine compartment? (I'm pretty ignorant about gauges and whatnot, so bear with me)

Thanks.

 

hehe my oil pressure is worrying me also

I run 30 psi at cruise
but if I have to rev it above 3000 it will hit about 110psi


once I was prolly pushing close to 140-160psi


I think it might have to do with my fram oil filter though

 

Maverick,

If you are running near red, you might want to worry about your cooling system before the oil gauge. Does it run this hot everytime you drive? If so, you will probably need a new thermostat.

Just a thought.


By the way, my oil pressure gauge fluctates too. But when it is not jumping around, it is at the right pressure. Any thoughts on what my problem is?

 

first thing you need to do is cool it down the oil is getting thinned out and the pressure is dropping off. and then see what it does. Also different filters do run different pressures I know that because I work at a dealer and we see it all the time, customers come in and complain their oil pressure changed after we serviced it. and as for your problem Brett sounds like the sending unit is going south. try "wiggleing" the wire that goes to it and see if it helps maybe its just a bad connection. Ive seen more sending units cause this than just a few of them.

 

First some fluxuation is normal in gm oil guages. when rpms increase so does oil pump speed and pressure. second, to rx7speed, oil filter would not cause overpressure unless it was realy messed up if at all but i doubt it. your problem could more likely be the oil pressure regulator (basically a checkball and spring held in by a blot near your oil pump inside your oil pan.

 

the oil pressure reg is near my oil cooler and it might be going
but before the oil change it was working fine

oil pressure was almost always at 60 psi
never above 80 psi


that was with 20w-50

now I am using 10w-30 and the oil pressure is going higher

when I used 10w-30 before it was fine and the switch to 20w-50 brought about a higher pressure at higher rpms but this oil change is making things wierd

and does any body know what pressure most oil filters let the oil bypass the filter element

 

freak things can happen. it is possible that just when you chaned you oil the regulator started sticking. never know

 

hehe I farted

sorry that was the bypass that is in the oil cooler and not the oil pressure sender

the oil pressure sender is right under the oil filter


and a sticking oil pressure sender wouldn´t show a high pressure now would it? if it was sticking it would show a lower pressure then normal and then be slow on comming down I would think

 

i wasnt talking about the oil pressure sender. a sticking pressure regulator would cause high pressure. all the regulator does is bleed off pressure when it is too high. if it sticks shut the full pressre from you oil pump goes to the lines.

 

sorry everyone keeps trying to tell me the sender on the rx7 sight

but they also tell me that the 10w-30 is what is making my oil pressure high, well atleast some of them

others have given good advice though


as for the oil reg, unless it is just slow to react


at cruise no matter what the rpm the oil pressure is just about the same

a little higher at higher rpms

it is under accell that the oil pressure rises really high

or if the car gets really hot.


I am thinking it is the oil filter though


before I put a new oil filter and oil in the car it was doing fine

and this time I used a fram rather then a quaker state





do you know what pressure these things go into bypass?