oil pressure

ok i have a 94 caprice ex cop car with 100,000 miles on the car. it has a L99 4.3 v8 and the oil pressure at cold engine temp is a little under half way on the gauge and when it is warm its right under the 1/4 mark. its not in the red but its allmost there that is when it is at ilde and at 65 mph its a little bit over 1/4 is this normal or what do i need to do.

Sounds like rebuild time - this behavior usually indicates excessively worn bearings.

at 100,000 miles??? it just turned 100,000 miles it used to be a dade county school board car no high prusuit. the oil is nice and brown and clean i can eat off the engine it was kept in really good shape. i find it hard to belive that my 100,000 mile engine needs a rebuilt. my brother has a crown vic with allmost 200,000 miles and his oil is nice and high.

Put an external oil pressure gauge on it and see what that reads - perhaps your sending unit is reading low.

I would not trust the gage to be accurate. They are only an indicator and what you see may not always be an accurate representation of the true oil pressure.

Also, before condeming the engine, replace the oil sending unit. These can go bad over time, I would do thtat right now and then observe the op. I know there was a problem with them on GM truck engines, I had a 92 5.0L V8 that showed low and it was the sending unit. Common complaint I was told, parts guy was well aware of new service part to correct the problem.

Run of thump is 10psi oil pressure for every 1,000 rpm. So high oil pressure is not necessarily always a good thing.

ok where is the oil sending unit??? is it hard to fix?? and is the part expensive?? thanks all of you

nope, it just pops out, and you pop a new one in.
i dont remember where it is, but there is a bunch of wires going to it.
look near the oil pan, which is on the bottom of the engine.
it should be easy to find.
i replaced it on mine in about 10 minutes.

There are two fairly common locations for the sending unit - the first is at the back of the block, oriented vertically and to the engine left (right-side as viewed from in front) of where the distributor would be on a normal SBC. The other place is a horizontal location just above the oil filter boss.

You could replace the oil pump. Not a high pressure or high volume, just a stock one. I did it on my truck at 120K and it did wonders for my oil pressure. Helped to rid the engine of an ever so slight knock it had too.

i would do that but isnt that a big job and expensive??

Replacing the oilpump would be fairly simple but they don't really wear, the relief spring can get weaker and limit max pressure but has no affect on low pressures.
Believe it or not all you have to remove is the baffle on top of the motor so you can hook a chain too the engine, pull the starter and oil cooler adapter, and TC inspection cover, low level sender, motor mount through bolts and lift the engine a few inches and unbolt the pan and slide it out. Cooling and exhaust can all stay attached.

I would start with the sender though and then if still low check with a mechanical gauge. The sender is behind the intake sort of under/behind the EGR.

Might find this interesting too, this is what I did and in my case I had to find the resistor since mine was a civilian car.
http://www.impalassforum.com/vBulletin/showthread.php?t=120641