Low Oil Pressure In My Mustang

[Ck250]

Hi guys I'm new here I have a 1988 Mustang gt I just bought it for $600.00 and it didn't run or drive. So I put a new fuel pump, ignition switch, alternator, battery in it and fixed some wiring that was all burnt up. I did a oil change on the car and the oil was black coming out and somewhat thick had to take a screw driver and put it in the drain plug hole to speed it up.I ended up doing a oil system flush on it before putting the new oil in ran it for about 20 minutes then put the fresh oil and filter in.

I took it out for a drive and I noticed the oil pressure was low I would get to about 2,0000 rpm and it just seems to stay at the first line then drop almost to the red when I get off the gas. I stalled the car and went to go start it but it had a bit of a hard time turning the engine. It aslo has a bit of a ruff idle I think its because of the old gas that was in the tank is mixing with the new gas.
Is it safe to drive the car or should a do something to try and fix whats going on? I'm just afraid of blowing the engine.

 

[TOOLOW91]

Without a mechanical gauge hooked up basing it off just that is kind of worthless. But the super thick oil points to maybe excessive sludge in the motor .

 

[mikestang63]

Run a bottle of MMMO through the motor and see if that clears out some of the sludge, Most likely the oil pickup screen, galley holes, and other parts of the motor are all clogged up. Take off the valve covers and see what it looks like underneath.

 

[Boosted92LX]

After reading that description, my money is on excessive bearing clearance due to wear. Seen it a hundred times. Went through it myself. I had a buddy that changed out an oil pump, didn't fix it, bought new rod and main bearings... still not fixed. Replaced the cam bearings, and lo and behold, oil pressure! I tried to tell him too, LOL..

When an engine has those kind of symptoms life hasn't been easy on it, and the only thing to do if you don't want to finish it off... is rebuild it. Or, replace it.

 

[Ck250]

I will try the mechanical gauge this week and report back with the pressure. Should I do another oil system flush? The oil is really clean now even after running it for a hour.
Also I am replacing the water pump and need to replace the timing cover because some bolts broke off in there but while I'm down there I will see if there is any sludge built up and let you guys know.

 

[mikestang63]

If the oil is already clear after a few changes, you dont have much options. Sludge is a sign of poor maintenence and leads to all kinds of problems. Hook up a mechanical gauge and see what pressure you have.

Broken water pump bolts are the norm for these cars. Put lots of antisieze on the new bolts. I would use SS bolts and studs. I believe Dorman sells them in the help section. Don't get a cheap auto parts store pump- they fail and their tolerances are crap. I would either get a Ford factory replacement or edelbrock

Ford Racing Mustang Stock Flow Water Pump (79-93) 5.0L M-8501-C50

 

[Gearbanger 101]

I see new bearings in your future. The good news is, that these engines usually experience very little (if any) cylinder wear over their natural lifespan.....so most of the time a set of rings and bearing make them good as new.

The bad news....the engine will have to come out and apart to do it.

If it were me, I'd pull it and give it an I overhaul after seeing what came out if the pan and what you're seeing on the gauge.

 

[Ck250]

I picked up a mechanical gauge but need to install it where is a good place to hook it up? I also took the car for a drive today she did very well just one little leak needs to be fixed in the back of the engine then there's no more leaks. But I noticed when I first started the car when the oil is cool the oil gauge is in the middle so about 4 lines up I believe but over time when she worms up it will drop to the first line. When I drive it she goes to about the second line then drops to the first if I'm a low rpms.

 

[RangerJoe]

To the right of the timing cover, about half way down the engine, you will find the oil pressure sending unit. You can unscrew that and hook it up there.

Joe