1989 toyota supra non turbo low oil pressure

[bayrat]

Hello to all I have a 1989 toyota supra non turbo that runs very well idles as it should but it seems to run warmer than usual.

The oil pressure seems low after warm up. it starts out at about 50lbs
then slowly goes down over a period of about 30 -40 miles to about 10-15 lbs this is on the stock gauge.

I can drive it to work about 60 miles the temp does not get high this is freeway driving @ 70 degrees I believe if I was to drive it in city traffic it would overheat. it has 99k on it I do not drive it often.

I have heard the fan run
The oil looks good.

I am hoping this is not a head gasket problem.

On a older chevy I had a oil bypass valve where the oil filter bolted to stick open causing low oil pressure.

The inside of the care seems harder to defrost than it should be the heater blows hot air but there may be more moisture than other cars I have.

Is there any inherent problems with these motors.
Like oil pump ,head gasket over heating.

If you were to drive this car 30 minutes to work and back in normal conditions you might not even know there was a problem.

I also had a problem with a head gasket on a ford motor where the oil looked fine but it was going into the coolant side causing overheating.

Any suggestions on where to start and look would be greatly appreciated.

The car is spotless But I would hate to pay to put a new motor in it

[Travis89Turbo]

http://www.supras.org.nz/techinfo/bhg.htm

See this link. All I did was a simple Google search to find this. Head gasket is the most common problem on the m series engine. You can send a sample of yoir oil to a company and they will tell u exactly what is in there. Very well could be antifreeze thining your oil causing low pressure. there is a block test you can do to tell u if you have a leaking head gasket. Is there any sign of oil in your antifreeze or any dissapearing coolant? How old is your oil?

[bayrat]

I will check the oil today it seemed ok about a week ago when I checked it. It was not runny and color was good. but today is the first day I have driven it I had this overheating problem about two years ago. I parked the car and am now trouble shooting.

After reading other threads this is starting to look like a bad head gasket
in its infant stage.

Another thread said to look at the number six cylinder would this be the back cylinder away from the front of the car.

[btwilson86]

BTW, your oil pressure is normal. These cars run a low pressure oil system, and on cold start up it should be over 40psi, at operating temp it can be as low as 3psi

[bayrat]

Thats good to know it has not suddenly gone down I am just more aware of it and constantly watching it.

[btwilson86]

Oil pressure will vary with wear, oil viscosity, and oil filter. There's a link in the online TSRM here that gives you the exact ranges and how to properly check your oil pressure.

[Green7mgte]

ty bt wilson.

go get a oil pressure checker and see exactly what its doing.
the stock oil pressure guage isnt terribly accurate.
if its within spec that your gtg. if not troubleshoot accordingly.

I could go into how the stock pressure guage works.. metal plates and big words and physics that I dont understand. but instead im gonna link you to a picture of a cat.