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high oil pressure

12-22-2004, 02:50 PM
When I start my z31 the digital oil pressure is at about 45 pounds, before the car warms up and i drive it pressure goes up to almost 90. After about 10 min of driving it will go down and sit right around 0. Even if I accelerate the pressure barely moves. Any advice?

12-22-2004, 03:34 PM might have some info on what the voltage from the oil pressure sensor is supposed to be. With the gauge reading 0 and the car still running, its a sensor or gauge problem with my guess being the first of the two. Check for damage or a loose connection around the sensor.

12-22-2004, 04:11 PM
Isn't the oil pressure sensor or sending unit IN the engine? It only gives a diffrent reading after the engine has warmed up. There isn't any diffrence in performance that I can tell.

12-22-2004, 04:27 PM
I've never worked on a Z31 so I can't tell you where it is, I know the Z32s is external, mounted next to the oil filter mount.

If there is no change in performance or idle then its defintately a gauge/sensor issue. If the oil pump wasn't working or was running a constant 90psi the engine would die. If it doesn't bother you that much then you could really just leave it alone. If you want to fix it, try giving longlivetheZ a PM or checking a Z31 FAQ.

12-22-2004, 05:17 PM
Cool I feel better knowing its a gauge. What would be some things that would make oil pressure run low?

12-22-2004, 05:48 PM
Failing oil pump, blockage in a feed tube, low oil level...etc.

12-23-2004, 12:31 PM
and if its running high it could be too much oil, wrong type of oil or both. Also if its low it could be a leak into the cylinders, but you would notice that quickly.

If there is no sounds of tapping or sputtering and your oil level is still good, then its the gauge, odds are its a loose or corroded wire/connector. Now comes the fun part finding it. It could also be a failling sensor, thats alot easier than tracing down a wiring problem.

01-16-2005, 09:12 PM
do you have a very low car? i have a z32 ,Mine is a few inches from the ground and that cause me my oil pump. I tried going over a bump but the bump was too high for the car and my crank was hit. that cause it to almost close completely my oil pump . try to see if your crank was hit that may be the problem. mine was also reading at almost 0 and the car continue driving. The only reason i didn't destroy my engine was because the cams are close enough to be lubricated even when there is almost no oil do to that they are very close to the pump etc.

01-16-2005, 09:23 PM
a good way to check if your oil pummp is bad is by taking all the oil you have in the engine and use the lightest oils possible example transmision oil. after you put the lightest oil you can find turn on your engine and see the readings of your oil PSI. accelerate a litle bit and see if the pressure goes up. MAKE SURE YOU DONT DRIVE THE CAR OR Keep that oil in there. That oil is only to test it and may damge your engine if you keep using it. Thats the easiest way to check for oil pummp problems. Do that before you start buying parts like most mechanics may advice you like the oil pressure sensor.

01-16-2005, 10:46 PM
If its low (0) when its warm, that could indicate a small blockage in the oil filter return line. When the oil's cold, its rather thick, and may be backing up against this clog. When the oil thins out a bit it may flow freely past.

At idle, its normal to have quite low oil pressure. I remember on my z31, whenever i'd take her for some spirited driving, the oil pressure would go up quite a bit, but when i'd pull over and tell the cop that my wife was pregnant, the oil pressure would take a dive right down to 0. That being said, i did have a warped head which would explain the 0 pressure.

To be honest, I wouldn't worry about it if its NA. If its turbo, then I'd probably get it checked out right away.


01-16-2005, 10:49 PM
yeah my oil pressure guage in my 90' only reads correctly when the engine oil is cold otherwise it reads 0, my 86' acts up every once in a while but for the most part it seems dead on.

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