Strange...

[1985 5.0]

It seems like every time i drive at night the car will overheat and the oil pressure will go up at the same time the water temp goes up. i cut the heat on for about 5 seconds, and everything goes back down to normal. there is a new oil sending unit, so i know its not the gauge. the car has 225k miles and underdrive pulleys on the water pump and crank. my dad seems to think that the radiator may need to be reconditioned or replaced. all i know is that by spring im not going to want to cut the heat on wide open to make the water temp and oil pressure go down.

 

[Strype]

Okay... that's a little strange. I've had all kinds of overheating problems but never messed with the oil pressure.

Try to change the antifreeze and take notice of how much comes out (1/2 gallon or 1 1/2 gallons?), if it's nasty and full of crap you need to have your system flushed and a new thermostat put in. You can take a garden hose and backwash the heater core. It wouldn't hurt to have that radiator routed or buy a new one at that mileage my friend...

What are the oil/water pressure readings?

 

[HISSIN50]

I still would be lookin at the gauges themselves. OP should drop with increased motor temps. 5 seconds is not enough to do anything, and turning the heat off would hurt a hot running motor.

Because this is all counterintuitive, I would look at your gauge wiring, esp grounds. If you mess with accessories (like turning off the HVAC fan, for instance), it can kick the voltage regulator around and get the input up, or change the dynamic with an insufficient ground.

My two cents. Good luck.

 

[1985 5.0]

Okay... that's a little strange. I've had all kinds of overheating problems but never messed with the oil pressure.

Try to change the antifreeze and take notice of how much comes out (1/2 gallon or 1 1/2 gallons?), if it's nasty and full of crap you need to have your system flushed and a new thermostat put in. You can take a garden hose and backwash the heater core. It wouldn't hurt to have that radiator routed or buy a new one at that mileage my friend...

What are the oil/water pressure readings?

its got a new thermostat i might start looking for a new radiator

 

[Strype]

I still would be lookin at the gauges themselves. OP should drop with increased motor temps. 5 seconds is not enough to do anything, and turning the heat off would hurt a hot running motor.

Because this is all counterintuitive, I would look at your gauge wiring, esp grounds. If you mess with accessories (like turning off the HVAC fan, for instance), it can kick the voltage regulator around and get the input up, or change the dynamic with an insufficient ground.

My two cents. Good luck.

I like his idea ^^^

I've had an oil guage in my old 86GT go nuts before after running a few minutes down the road. It happened the whole time I had that car off and on.

 

[The Shape]

I would be looking at the gauges themselves. I know I have more oil pressure with my headlights on than with them off . The stock electrical systems in these cars leaves a bit to be desired and the gauges are not very reliable. Alot of people have had this same problem where you cut and accesory on and your water temp or oil pressure rises.

 

[Black1987Stang]

I still would be lookin at the gauges themselves. OP should drop with increased motor temps. 5 seconds is not enough to do anything, and turning the heat off would hurt a hot running motor.

Because this is all counterintuitive, I would look at your gauge wiring, esp grounds. If you mess with accessories (like turning off the HVAC fan, for instance), it can kick the voltage regulator around and get the input up, or change the dynamic with an insufficient ground.

My two cents. Good luck.

I agree with him, def. part of the wiring or grounds. Best way to tell is put on a mechanical oil pressure and water temp gauge and see what happens. Sometimes when my gas idiot light comes on, when i put the headlights on the gas light goes out