My overheating problem

[The Rev]

Ok I know theres a bunch of these threads open now, so forgive me for starting a new one.

It's been overheating ever since I blew the cats last fall.

Only ever overheated to the point where I lost coolant 2-3 times during that span.

Replaced the crossover pipe (to properly burp) no change

Replaced the coolant sensor/sender.

Water pump is new

Just had a mechanic friend of my moms replace the tstat, and while he was in there he pulled out the fan and tested it.....heres where it gets dicey.


He says when he tests it with a straight connection, out of the car, nothing happens, its grounded but no power to the fan. He said there is power at the connection, but not at the fan itself.

I still haven't driven it so who knows.

I'll be looking into a fan, they seem to go for 60 on ebay, anyone know any other places to check?

 

[Frogman]

Check the little electrical connector tabs that go into the fan. The fan draws a lot of juice, and over time, it will melt them. Happened to me on a 98.

Worth a shot.

As far as fans... the Mark VIII fan is actually a really good design. I'm sure KK might have a few hooked up in place of ceiling fans. Hit him up, see if he has one.

 

[XLRVIII]

+1
The contacts on the fan motor get eroded and the plastic connector in the wireloom also gets melted and deformed causing a connection problem.

Might want to replace the end of the wire harness before you dive into the fan...just a thought

 

[The Rev]

I wish I could say the connectors were in tough shape, but they're both perfect, oddly enough seeing that nothing else on this car is. The thermostat housing was jb-welded together and both bolts snapped while he was doing it, so he had to drill them both out and replace em with standard nuts/bolts, and the thermostat itself looked terrible, horribly corroded.

On a good note, he'll fix my rear quarter for 400 including paint, so that's cool.

Its a stupid question....I know the fan for the Mark is a really good design and moves a lot of air, but could that really be the problem? Can that fan really keep it from overheating?

 

[Frogman]

Well...

Let me ask you this. Does the car overheat on the highway, at highway speeds? If so, then it's likely not your fan.

If the car only overheads in the city, at speeds below ~40mph, then... maybe your fan isn't coming on.

Maybe I didn't understand your original post, so please clarify:

Does the fan run out of the car?
You have power to the fan wires that plug into the fan, from the car's harness, yes?
And to answer your question, yes, the fan can keep the car from overheating. That's kind of what it was designed for. But a fan usually only kicks on at speeds below ~40mph, if it needs to, in order to (obviously) move more air over the radiator.

 

[The Rev]

Sorry for being vague...


Fan, out of car, will not turn on.
He says there is power coming to the harness that goes into the fan.
I actually just bought a voltmeter yesterday at harbor freight, I'll check myself.

And yeah it won't overheat on the highway.

 

[Frogman]

Then.. it sounds like the fan motor has had it. Buy another fan, put it in, and be happy.

Put that meter on the two leads on the fan, and see what kind of resistance you're getting across the motor.

You might have to move the blades a bit, to make sure the brushes are contacting the stators.

I'm willing to bet you have a toasted fan though.

 

[The Rev]

Thanks for the help, they go for about $72 shipped on ebay. I could get a brand new fan motor for 100 locally, so we'll see.

 

[Frogman]

I'd get the local one. By the time you pay shipping, (I know, you have to pay taxes locally), you won't be that much in the hole. And if it doesn't work because your car has other issues, you can always take it back for a refund...

 

[topher5150]

is there a fuseable link in there, i think that's what happened to my car something to do with the harness

 

[Frogman]

He has power to the fan leads on the harness.

 

[The Rev]

I already ordered one, 72 bucks on ebay. I'll update when I get the fan.

 

[The Rev]

Fan works fine, still gets hot, I JB welded a nut to the top of the crossover cap, will burp and update.

 

[XLRVIII]

Only ever overheated to the point where I lost coolant 2-3 times during that span

only takes "once" to lift a headgasket.
That is what happened to Tiffs 93, her mom drove it, overheated it ONCE.
headgaskets were popped..
No coolant in the oil.
No oil in the coolant.

it would simply overheat and start pushing coolant out the overflow tank..


This wouldn't be the first time I'd heard of an overheated mark busting the headgaskets.

Once on tiffs car
Suspect one on a currrent overheating problem...with someone elses car
and.. yours.

Sorry to say.

Have you had the coolant tested for the presence of combustion gases?
the cost of the test would be worth the peice of mind.

 

[kustomizingkid]

Getting that dye tossed in there is cheap and will help you plan your next move quickly...

 

[cadillackman]

What blew your cats? I'm asking because if you were burning coolant through your exhaust via head gasket, the vapors could corrode your cats fairly quick from what I've heard.