Nickstang

I have a 90 5.0 LX. I have recently replaced the intake and timing cover gaskets. The problem is after the car warms up the oil pressure completely drops. It'll go up as long as I'm on the gas. The problem did not exist before I resealed the top end. Oil pump is very new(doesn't rule it out, I know). There is definite pressure loss. Not a guage problem.

Could the cylinders be getting too hot, heating up the oil causing it to losing it's viscosity? Would this be due to the EGR system? Is this possible?

Any and all suggestions will be helpful.

Thank you.

mdvaldosta

Hopefully theirs no trash in your oiling system from when you opened it up clogging an oil galley or something. Could be an oil pump, could be a few things. Do you know what the actual pressure is? You may want to get an aftermarket gauge to at least screw in to verify your stock gauge is working right. I'd go the oil pump route first if the pressure is low.

50fiend

I have exactly the same problem. I was wondering if it could be the sending unit.

roundman

could be a bad sending unit or the pipe extension leading to it is partially plugged up and is restricting the pressure reaching the sending unit. it's located just in front of the oil filter on the driver's side of the lower block. unplug the single wire going to the sender, remove the sending unit and then remove the extension pipe and clean it out good, also clean out the end of the sending unit where it screws into the pipe fitting. reinstall all this and see if the pressure reading improves.
hot oil will lose some vicosity but it should not make the pressure drop way low like you describe. How many miles are on this engine???

BlueDemon

I had the same problem also and I was leaning towards the oil pump not working. I went and borrowed a oil pressure guage from my mechanic and found out that I had plenty of oil pressure when my stang was warmed up and that my guage was malfunctioning. It worked well when it was warming up, but once it got warm it was reading almost nill pressure unless I had the engine reving at almost 2000rpm. I replaced the factory oil pressure guage with an aftermarket one and put it in the top center of the steering column so I could still see my speedometer and rpms along with the volts,temp,and gas guage. I would do what mdvaldosta said and get your guage checked. Good luck!!

vfast

always try the easiest and cheapest route first

Nickstang

This is in response to Roundman's question.

90 LX 5.0 Coupe...When I bought it, it had 3.73's with no speedo correction, I'm guessing 160,000 miles.

I'll give it a go and take it from there.

Thank you.

roundman

with that many miles, you probably have some bearing wear which is opening up the clearances which will lead to a lower oil pressure at idle than you think is normal but as long as it comes up with the engine speed you are probably getting enough pressure to keep things lubricated OK.