aamilo

I have a '91 lx with the 2.3 4cyl. once the car gets warm (and sometimes when it is still cold) the oil pressure gauge will show quite a bit of movement. When I bring the rpm up on the motor, in gear or in neutral the pressure gauge will go down to 0. If I let the car idol the gauge will come back to normal. I have only driven the car a half dozen times but right after I changed out the head I took it for a long run and the pressure went to zero and the motor started to knock real bad. Sounded just like a diesel and started to smoke blue. Then today the knock went away, the smoking stopped............... I have the car in for an oil pressure test right now, I don't know why the knocking would stop, if the head is not getting oil I don't know why it hasn't seized, the car has plenty of power (at least for the 2.3). If the berrings were gone oil pressure would go up with high rpm and down at idol (opposite of what is happening).

Any thoughts I am going to loose my mind on this

roundman

your problem could be the oil return holes in the heads are blocked and when you rev the engine the oil gets trapped in the head and can't get back down in the oil pan where the pump can pick it up and pump it generating pressure. you could also have a partially plugged oil pump pickup screen or a lot of sludge in the bottom of the oil pan too. I would pull the valve cover off and see what kind of shape the inside of the cover is in as far as oil sludge buildup and stuff, then based on what you see, decide is pulling the pan is a good thing to do to clean it out or not.

aamilo

thanks roundman. The oil could be getting trapped. When I replaced the head the gasket had pinpric size holes for the oil return where a finger size hole in the head and block appeared. The head shop/part store/someone from the forum said this was normal. My honest guess was the pump or the pickup. I guess we will need to see what the oil pressure test reveals.

any thoughts on why the motor would start ticking and then "fix itself"?

roundman

the hydraulic lifters only work properly when there is sufficient oil pressure to keep them "pumped up", so when the pressure drops, the lifter collaspes a bit and this opens up the valve lash and lets them tick tick tick. once the pressure is back up, the lifter pumps back up and the lash closes back to zero and there is no tick, tick, tick noise. I don't buy that bit about the oil return holes in the head gasket being small pin ****** being normal. I would pop off the head and open up those holes to match the hole size in the block so the oil can drain back down into the crankcase from the valve area. the oil pump can't pump it if it ain't in the oil pan you know! LOL

IownaMustangNow

lol is there oil in the car

aamilo

YES there is oil in the car, tranny fluid and antifreeze too

I contacted another parts vendor and they confirmed that the oil return holes should be smaller to slow the flow of oil back to the pan. Older V8 motors have the same size hole in the gasket, block and head.

Seems like a stupid system to me but.........

If the Oil pressure test doesnt' tell me anything I will rev the motor up and when the oil pressure gauge reads nothing I will check the dipstick to see if there is oil in the pan.

FYI the oil pressure gauge did this before I replaced the head gasket and the old gasket was identical to the new one.

vfast

for a kwik fix use a thinner oil... I agree with the old man..if there is a ton of miles on the car..use a qt of engine cleaner to dissolve some of the sludge...fords were famous for this back in the day when folks used quaker state and didn't change oil right..pull the valve cover and look at the return holes use a shop vac when cleaning the crap on the heads

Chopper

You can drain all the old oil out.Then get a clean pan and pour diesel fuel into the engine,about a gallon.This will drag most of any LOOSE gom* into the pan.Let it drain for awhile and replace with new oil and engine cleaner.Run it for a few miles and change again.This time,cut the filter open with a pipe cutter or something that won't get filings into the filter.Look at the pleats in the filter and see what's in there.Black coffee grounds are carbon,shiny glitter could be bearing material or steel from lifters,cam lobes,or rings.These will be attracted to a magnet. *GOM.-Noun-Dirt,goop,crud,crap,etc.Verb-To mess around.A southern Wv term.

aamilo

Arghhhhhhh. So the mechanic can't do a pressure test because he doesn't have the correct fitting. BUT they couldn't get the oil pressure to drop. So I picked up the car, drove it home and now I can't make the oil pressure drop. Arghhhhhhhhhh. And like the mechanic said unless we can recreate the problem it is likely that the pressure test would come back normal.

Hey Chopper Can I use a gallon of Varsol/paint thinner to degrease the engine or is Diesel fuel better.