Car overheating

[Husqy510]

I have an 88 Mustang with a 331 stroker motor making about 425hp. It's running a Mishimoto aluminum radiator with an electric fan and a belt driven water pump. Up until last week it's always stayed at 180, unless I drove it hard, at which point it would get up to about 210.

This last week I was driving home from work on a cool morning and I look at the temp gauge and it was hot. I immediately pull to the side of the freeway and pop the hood. It wasn't steaming or smell hot, and the motor was running fine with good oil pressure. I limped it off the freeway and noticed the temp dropped, but then got hot again. While waiting for the tow truck I removed the radiator cap and a fair amount of coolant came out and it was obvious there was a fair amount of pressure in the system. I then started the car and didn't notice any coolant moving through the radiator, and the hose was soft.

Once home I replaced the thermostat and took it for a drive. Initially the temp bounced around before settling at 180, so I assumed I fixed it. This morning I took it for a drive and it heated up to about 220, so I pulled off the freeway and removed the radiator cap and a bunch of cold coolant came out. So again there was a fair amount of pressure in the system. I let it idle with the cap off and I once again didn't notice any coolant flowing, but the temp was stable at 220 on the gauge. On the short drive home the temp would drop to about 210, but then go up to 240 so I'd throw it in neutral and coast, at which point it'd go back to 220

Is it possible the water pump failed, or is slipping?

It's not leaking any coolant anywhere. No coolant in the oil. It's running a mechanical autometer temp gauge.

 

[t&y]

I was thinking the water pump too. Just not too sure how that is possible. Did you check the belts for any unusual wear? Any possibility the pump is frozen or maybe the shaft not spinning inside the pully?

Another crazy thought, check the air dam on the front of the car and make sure you didn't get a large piece of plastic or something blocking a good portion of the radiator.

 

[Husqy510]

Air damn and radiator is clear. I removed the belt and the edelbrock water pump spins freely. Next thing I'm going to do is drain coolant and run water through the radiator to make sure there are no obvious restrictions

 

[95Enforcer]

Ive had quite a few fox body mustangs in the past and the main issue I would go with here is the water pump. I have had water pumps fail without any leakage or any signs of another problem. Also need to check the motor at temp with a temp gun to verify its hot and where it is getting hot to verify you dont have a blocked water passage. Also check the tube on the passenger side intake to the heater core and temp gauge if its mounted to that or the intake manifold. Not sure how your motor is set up. Id check temps to verify the temp sender is reading correctly.

 

[ElAzul]

If the motor was hot and coolant was cold that tells me thermostat may be keeping it in the radiator. Any chances of air pockets?

 

[Husqy510]

Thanks for the replies.

I don't believe there are any air pockets. As mentioned above, it ran great until last weekend, so I think something failed. I verified the old thermostat was operating correctly, so that was never the problem.

The mechanical fuel gauge is hooked directly to the intake. The bypass is still hooked up to the heater as well.

 

[95Enforcer]

If the motor was hot and coolant was cold that tells me thermostat may be keeping it in the radiator. Any chances of air pockets?

the sbf on these cars do get an air pocket on the upper radiator hose at the intake manifold inlet do the height and bend in the hose. I always do an 1/8” hole in the thermostat to solve that problem. Could be a possibility but usually would know right after an initial coolant fill.

 

[Husqy510]

the sbf on these cars do get an air pocket on the upper radiator hose at the intake manifold inlet do the height and bend in the hose. I always do an 1/8” hole in the thermostat to solve that problem. Could be a possibility but usually would know right after an initial coolant fill.

The new thermostat has a small hole just as you describe, so i don't think that's the issue. Good thought though

 

[DRYHEAT]

Defective/bad water pump, Impeller may be spinning on the shaft not moving any water?

 

[ElAzul]

Pretty obvious problem the distributor is on the wrong end. Junkyard LS swaps don't overheat

 

[Husqy510]

Defective/bad water pump, Impeller may be spinning on the shaft not moving any water?

That's what I was thinking, so I ordered a new pump.

 

[Ty N]

Water pump!

 

[ChumpChange]

Pics of car?

 

[River Runnin]

Always thought 195-220* was normal operating Temp --- 240-250 up and over! Head Gasket might be going..

 

[Husqy510]

Not my favorite way to view the car

 

[ChumpChange]

Still a great looking ride.

 

[infield]

I (Township) had a Cat motor grader (new) that started getting hot and dealer pulled off the water pump and all the fins were broken off. I know not the same but sometimes you will find crazy things.

 

[95Enforcer]

Not my favorite way to view the car

Great looking fox.

 

[Husqy510]

What do you guys use to seal threads on bolts that go through to the water jacket? I used some thread sealer and it leaked like a siv. Maybe the threader sealer was old, or maybe it needed to set up longer. I was thinking of use permatex #2 and gasket and bolts this time.

What do you think?

 

[95Enforcer]

What do you guys use to seal threads on bolts that go through to the water jacket? I used some thread sealer and it leaked like a siv. Maybe the threader sealer was old, or maybe it needed to set up longer. I was thinking of use permatex #2 and gasket and bolts this time.

What do you think?

I just use the black permatex gasket maker for the threads and the gaskets. Never had an issue.

 

[DRYHEAT]

With trepidation I’ll answer what I personally use. Permatex ultra black or ultra red which ever I happen to have.
I am sure the professionals will tell you differently.

 

[Husqy510]

I cleaned it well and reinstalled with permatex on threads and gaskets. I'll let it set up over night and add fluid tomorrow

 

[Husqy510]

Success! Thanks for the help.

 

[95Enforcer]

Success! Thanks for the help.

Awesome. Enjoy driving it now. Post up some video of it running.

 

[Husqy510]

 

[95Enforcer]

Sounds wicked nice. Here a link to one of my okd foxes. My youtube page has a few of my other cars as well.

 

[ChumpChange]

Yeah I’d rock that.

 

[Husqy510]

@95Enforcer that thing sounded rowdy for a bolt on car with a cam. These cars are a blast. Cheap, lightweight and easy to work on. My last one was a total sleeper with a blown 347 making 500/500 to the wheels

 

[ElAzul]

Not my favorite way to view the car

Burn out leaving a car show?? JK

 

[Husqy510]

Put about 100mi on it, some in the hot weather, and its no longer overheating or leaking. One interesting change is it now runs about 160, even though I installed a 185 thermostat. The only time it got up to 185 was in 100 degree weather, and it held steady there.

I installed a fail safe thermostat, which is supposed to fail open. I wonder if it flows enough to keep it at 160 when its not hot

 

[ibelio]

open old pump find the problem let us know thanks

 

[Husqy510]

open old pump find the problem let us know thanks

I opened the original pump and no obvious issues. I also tested the original thermostat and it was working appropriately.

This all started one morning when I showed up to work and steam was coming from under the hood. I determined that a heater line had sprung a leak so I replaced it. On the way home from work it overheated and I assumed it was the thermostat, so I replaced it, but it still overheated.
The interesting thing, is it didn't just peg the gauge, it bounced around, but never seemed to go below 210. The radiator is new, so i figured it must be the water pump.

Now im beginning to think it developed an air bubble in the system when i replaced the heater line.

 

[95Enforcer]

I opened the original pump and no obvious issues. I also tested the original thermostat and it was working appropriately.

This all started one morning when I showed up to work and steam was coming from under the hood. I determined that a heater line had sprung a leak so I replaced it. On the way home from work it overheated and I assumed it was the thermostat, so I replaced it, but it still overheated.
The interesting thing, is it didn't just peg the gauge, it bounced around, but never seemed to go below 210. The radiator is new, so i figured it must be the water pump.

Now im beginning to think it developed an air bubble in the system when i replaced the heater line.

The air pocket is very possible since these cars are probe to it. Hopefully no more issues from here on out and enjoy driving the car.