Low Oil Pressure when warm.

Bought a 104K mile 1992 Roadmaster Wagon w/ tow pack last week for $1200. Car is near mint except for the second row power windows and this oil pressure issue I've been having. This forum has been very helpful so far from just peeking around and reading about it.

When the car starts cold oil psi is around 40. As it warms up pressure will gradually fall until it hovers and usually sits on the low oil red area, suddenly I'll get valve clatter as well so I know the gauge is telling the truth. Warm starts after that are the same, some clatter and 1/3 times it will rise again under power. Did an oil and filter change to synthetic 10w-30 to see if that would help clean things out. It did improve the cold starts but my warm low oil pressure is still happening. Any ideas as to what could be the case? The car did sit for a while so I think it could be some sludge getting loose when the engine warms up and clogging the pump.

I've seen very little metallic flakes in the oil and the valve clatter isn't too bad so I think the motor is still ok, I'm fine with an engine swap but am too swamped with school and work for that project at the moment. I'm assuming worst case scenario and I have to change the oil pump. From what I've read that involves lifting the motor slightly to remove the pan. Are there any write ups for this job anywhere? Haven't bought a haynes/chilton/bentley manual for the car yet either.

Thanks for any help,
Morel.

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Don't buy a Haynes/Chilton worthless manual, either. Buy the real deal, right here:

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Good luck resolving your issue. I don't know what's involved in the job, but someone here surely does.

Purchased! Thanks for the link.

I did the oil pump I about a day. The issues you may encounter are putting the crank timing mark at the 6:00 position, removing the starter (you have to remove the triangle frame brace, and the trans cooler lines. You have to remove the distributor cap and rotor to get clearance, as well as the trans dipstick and tube. The top fan shroud will interfere with the fan when you lift the engine if you do not remove it. Everything else can stay hooked up. You should consider a new pan gasket, but if the old one is in good condition, a little RTV at the sharp corners will be necessary. I would put a metal pump drive shaft connector on instead of the nylon one they give you. You can get the metal one at a speed shop. The pump and the pickup are sold separately, and you have to assemble them, which is a PITA. There is a tool for it, but you need a press. I had a mechanic assemble mine before I started. I did it in one day, but it took the whole day. I put the car high enough on jack stands to easily get under the car. A sheet of cardboard makes it a lot more comfortable when laying on the ground.

run straight 30W

I was going to say try a thicker oil, and forget synthetic. Ran thicker oil in my Olds 307-Cutlass with low oil pressure until I swapped in the 350. Still had low pressure but with the thicker oil at least not in the red.

You could always try to flush the engine...the pickup screen on the pump could be clogged from sitting or lack of previous oil changes. A flush might help. I've used STP Flush before. Just make sure you change the oil pretty quickly.

Good luck and keep us in the loop. Looks like a nice car.

-Mike

-Mike

Starting too see how labor intensive an oil pump replacement is, makes me want to jump ahead and swap the engine.

What does everyone think of that? I'm not looking to get 500 whp out of this thing so any LT1/LSx/LQ would be fine with me. Whatever the easiest plug and play motor there is I'll shoot for that. The cold starts are getting chattery now too so I'm not sure this L05 is worth keeping. I'm currently in Bozeman, MT so any GM V8 is fairly easy to come by.

Same here, thicker oil. Currently I run 10W40 in the Caprice. But hey, if engines are easy to come by, go that route. Good luck
Pete

Just found a TBI 350 out of a 1992 1500 truck on craigslist for $400, higher miles but everything's good on it. Might just do a straight swap for now. Also just found out the gas gauge doesn't work. 3/4=empty.

your car seems to have the rubber deleted except in the piece of chrome under the right lights.
If you take that one off, I'll take it! Is the ONE piece of rubber I'm missing..

good luck with your oil pressure issue.

I'd try the 30W like Nick said and see if that helps before I went off and bought another engine, just sayin.

I topped it off with 10w30 and for now the valve chatter has stopped, seems much smoother and runs ok. Gauge still drops to zero when warm. Got a few engines in my sights that would be dandy to put in, just waiting for this one to die now.

Ok, just got found an even lower mile TBI for $400, runs great. How straight forward is a plug n play swap? Disconnect tranny, pull motor, pick and choose the better accessories, ???

I've pulled motors before, just wondering if there's any funky stuff to look out for.

If the engine is the same, there should be no problems, straight swap.
Pete

Well, picked up a TBI ZZ4 block. Should be an increase in power. Still tearing that apart to clean. Might do a cam, mostly need to figure out how to get this hodgepodge of parts together.