Oil pressure!

[Bad Co.]

I have a 99 t/a and i think my pump fixing to go down. In the mornings my o/p is about 40 lbs. Then when it warms up it will run about 20lbs when i stop @ a light. Last night is went a hair below 20 and when i was driving about 1700 rpms it wouldnt go over 20lbs. Can someone fill me in on whats going on? Is this normal? Am i fixing to be putting a oil pump in? By the way I dont know is this matters but i do have quite a few bolt ons, heads, etc.

[c5z28]

The earlier oil gauges are more accurate than the later ones. Mine usually reads just under 40psi at idle how many miles do you have on it? I'm no expert but you could take off a valve cover and see if it is getting oil up there.

[Bad Co.]

just turned 90k

[Cutlass]

it might be a pump but could also be a bad gauge or worn bearings

[gnomee]

Are you low on oil? What kind of oil filter are you using and how long since the last oil change?

As long as its around 20 and increases when you are above idle, I would not worry right now.

I don't know the specifics but technically speaking the engine needs a relatively small amount of oil pressure per 1000 rpm. Someone who knows that figure might chime in but at 20psi while idling your fine.

I'd keep watching it like you obviously do out of normal driving and not worry about it.

[Cutlass]

generally 10 psi per 1000 rpm is safe

[Vexzer]

...i do have quite a few bolt ons...

Time to bolt on an oil pump. [Just kidding.]

Change your oil before doing anything. Use the right stuff according to spec and temperatures.

If you are really worried, t-tap at the stock sending unit and mount a mechanical gauge under the hood for monitoring purposes
[a man with 2 watches never knows what time it is].

[Bad Co.]

I think i might be ready for a oil change. I only run mobil 1 5-30 with a ac delco filter. But i also think im going to change the sending unit cause i caught wind by a trusted ls1 mech in my home town saying that some of the early ls1 cars have faulty sending units behind the manifold.

[Vexzer]

ac delco filter

Inside word is that the WIX filters at O'Reilly's are best as far as common retail products go, & Fram & some other advertized names are poor.

[JRENIGAR]

OP, I had the same problem with mine with 140k on the clock. I was getting around 18-20psi at idle when warm and around 30psi at 2000rpm and above. I was running 5w30. I Just changed the oil and went with 10w30 and now it has 50psi when cold and 35ish when warm. BTW Chiltons manual says 6psi at idle is fine. 20psi at 1000rpm and 30psi at 4000rpm is sufficient. Seems kinda low to me but thats what the book says. Try the 10w30 oil change first and let us know.

[SteveC]

An obscure point, it maybe a bad electrical sending unit.

SteveC

[JRENIGAR]

^^^ this is true.

[cammed goat]

Try swapping out senders and see if there is a discrepancy in pressure readings. And make sure you are not leaking any oil as some senders tend to crack and leak over time.

[Bad Co.]

Im changing the s/u this weekend. My car has NEVER leaked a drop of oil or burned any. The runs like a cheetah with hitops. Thats what i dont understand. shes my dd that why im so freaked out. But hopefully this weekend i will find out. Fresh oil change and new s/u. I will post the results asap. thanks for all your help.

[cammed goat]

Keep us posted.

[Bad Co.]

ok gentlemen, it turned out to be ONLY a sending unit. Everything went very well. Untill yesterday. my frikin blinkers stopped blinking. I checked every single lightbuld, and peanut light. All was good. Fuse was good. Just when i was gone give upi made a phone call to a very trusted f-body guru. ls1.com user name "venomous". we nailed the problem out quickly. it ended up being a frikin blinker relay. 2.99 part. I hope that this thread helps somebody. And thanks guys for all your input.

[cammed goat]

Glad to hear ya fixed your ride.

[neophytal]

20 seems low to me, never got that far on either ls1 I've had. I think the worst was like 35, and that was because I was sitting for a few hours on a strip cruising