camarokid24

Ok , so last night I was running around and I stopped to drop off a friend and noticed that my oil pressure was down sitting on the first red line This is after about a half an hour of driving so it was warmed up. When the car is at 2000rpms the oil pressure is at the 1/4 mark. Is this too low? I checked the oil level and it is full. I know when the car is in closed loop the idle rpm's are high like 1000 untill closed loop and then the pressure drops with the rpm to 400 or 500. Can anyone give me some insight on what might be my problem if any at all. Also the car has 88'000mi on her, I have searched on this but havent found much info that I can make sence of . Thanks Anthony

FastZinTennessee

Did you say your idle RPM drop to 400-500? If that indeed is an accurate reading (your factory tach may be off) then that idle is too low.

You can fix the low oil pressure at idle by stepping up to a thicker oil. Mobil 1 5w30 oil gave me such low oil pressure at idle that it made me nervous. It showed pressure low enough to make the "check gauges" warning light come on a time or two. When I switched to Mobil 1 0w40 it showed around 15 psi at hot idle and gave me almost 10 psi increase per 1000 RPM which is exactly what I was looking for. You might try that on your next oil change.

indieaz

When you say the 1/4 mark i assume you mean the 20 PSI hash mark? At 2,000 RPM cruise that's not normal...every LT-1 i've seen (in stock configuration) including both of mine run around 20-25psi idle and around 50psi cruising 2,000 RPM. The oil pump pickup may have come off or your sending unit is messed up. Try hooking up a mechanical guage and see what happens (or simply try swapping the sending unit).

EDIT: Oh yes, and if the idle speed is actually dropping for 400-500 RPM then your tach is either off or you have a problem. It's possible the IAC (idle air controller) is gunked up a bit. I would suggest unhooking the battery then turning the key to the run position and off to reset the computer, this will make it relearn IAC position which might help.

camarokid24

I guess the oil pressure at idle is not low enough to set off a warning light but still I jhave never seen low enough to be on a red mark indicating that it is in the "danger zone" I allways monitor all my guages while driving and this problem just appeared lat night and I took it for a drive today and it is still the same. Good then it is in closed loop but bad after it is hot enough. Thanks for the ideas I hope it just the oil pick up tube .

indieaz

Oil pickup is pain cuz you gotta drop the pan to get at it...the sensor is a pretty easy change in comparison.

camarokid24

Ok So I disconnected the battery tuned the key to acc on and off then pluged it back in and started the car took it for a drive and seemed better at first the rpms in park are at 600 and in drive the drop to 400 or 500 the oil pressure at idle with it in park is just above the red first red line then when put in drive it drops to sit right on the line. Guess I will have to figure out where I am going to work on her at. I live in a apt. complex so I have no garage and there is snow all over the place thanks again for all of your sugestions guys If I drop the oil pan will I need a new seal?

FastZinTennessee

I wouldn't just go and drop the oil pan. It is a major pain in the ***. You have to get the car up in the air, remove the low oil pressure sensor, remove the torque converter cover and move the cooling lines over if it's an auto, turn the crank a certain way, disconnect the exhaust and jack the motor up enough to clear getting the pan out. I know it's possible but I haven't personally known anyone with any GM product that had their pickup tube fall off.

These cars are notorious for low oil pressure at idle, and add to the fact that your car may have an unusually low idle. If you get out driving around and find that your oil pressure is dropping very low or to zero when you get the engine speed up high then I might investigate the pickup tube.

camarokid24

So it could be just that the oil pressure sensor is not reading right and giving false info to the guage? Or could the oil pump be going bad? Aslo How would I go about checking the oil pressure with a guage that I would have to buy?

camarokid24

Oh GOD all that to get to the sensor so I guess its no the pick up tube. it stays at just above the 1/4 hash mark no matter what rpm 3000 to 4000. god this sux

FastZinTennessee

No no, all that for the pickup tube. The oil pressure sensor is located on the back of the block, it's over towards the drivers side mounted to the block behind the intake manifold. It's a little difficult to get to simply because that area is under the cowl. If you look at it, it's just a smallish sized black barrel that has a metal fitting on one end and a small harness plugged into the other end. It screws directly into the block.

Edit: if your at 3-4000 RPM and you're still only a little above the 1/4 mark on the gauge I would hook up a mechanical oil pressure gauge as has been suggested ASAP. You can hook the mechanical gauge up where the factory sending unit that I was talking about above threads into the block.

30696bird

http://shbox.com/1/oil_pressure_sensor.jpg

indieaz

It is possible it's the sensor - you'd have to hook up a mechanical guage to check. Your car is a '94, so it could be behind the intake manifold or next to the oil filter. I would check with a maech. guage to be sure first. But yah dropping the pain is a total bish so don't go there until you're sure that's it! I thinkt he low RPM problem is contributing - you should try resolving that first...400rpm at idle is really low. It should be more like 650.

camarokid24

Indieaz, What should the idle be when in gear? See the rpm starts out at 600 to 650 then slowly drops to where I peviously stated. I will try to check with a mechanical guage the oil pressure. I just dont know what would cause the idle to be low.

FastZinTennessee

I'm not 100% sure but I think idle in gear should be 600-650 RPM. I'll go check the Haynes manual.......

Edit: can't find anything conclusive in the manual. 600 RPM +/- 50 should be ok.

camarokid24

thanks Fastzintennesee and to everyone who has tried to help me