Overheating and wont stop!!!

sho_shane · Jun 14, 2009

Ok I have a 94 Cobra,In the past week iv put in:
New Waterpump
New T-Stat
New Rad

Iv done a Block test on it and came back neg on blown heads,
Iv put a Laser temp gun on it and when its over in the red on the guage the motor is sitting at 214-218.
So I know the guage is off. Someone has hard wired the fan in and from what I can tell they did it off the headlight harness.

When you turn on the toggle for the fan it turns the front headlights and front park lights on very dim. But when you turn on the headlight switch to turn on the headlights for night driving it turns off the fan. Im really not sure whats going on here.

It does take some time to start overheating. I drove it yesterday, I let it warm 1st then took it into town. For 10mins or so it ran fine. Then the guage started to rise.
Also it will not over heat at all with the cap off. I know it sounds like head gaskets but the test came back neg. :dontknow:

So im really stumped on this one.

95 svt cobra · Jun 14, 2009

Has this started since youve replaced the T-stat? If so it may be in backwards

Also, iirc, i dont think that the fan should be wired into the headlight harness, that sounds really off to me. Mine donest go anywhere near that harness, i wanna say it goes to the harness that that plugs into the CCRM.

AaRoN · Jun 14, 2009

Have your cap tested.

sho_shane · Jun 14, 2009

The cap is new, I got it 2 days ago when I got the new rad.

AaRoN · Jun 14, 2009

Have you burbed the cooling system?

sho_shane · Jun 14, 2009

Im going to say yes. But just incase im doing it wrong. Can you please tell me how to do this?

CC'S95GT · Jun 14, 2009

The fan definately doesn't need to be wired with the head light harness. the HL harness is barely enough for the lights themselves much less the added big amp draw from the electric fan. Is the fan coming on in hi speed or low? Is the fan turning the right direction?

sho_shane · Jun 14, 2009

Im not sure at all on the fans speed. I can tell the that it is blowing on the motor. So I guess that would be saying that it is pulling and not pushing.

Im going to go out n a min and unhook all the hacking job thats done. Im going to see what it will take to make the fan work like it was from the fac. Or at least wirer it to a toggle that will let me do high speed and low speed.

Does anyone have a wiring diagram for how to do this?

CC'S95GT · Jun 14, 2009

a haynes manual might have it in the back. the connector on the fan only has 3 wires. 1 gnd, 1 low, 1 hi speed. should be pretty easy to figure out. i would also install a relay instead of the sw handling all the current. you don't both the low and hi speeds on at the same time.

sho_shane · Jun 14, 2009

Ok well did some un taping and this is what I found:

sho_shane · Jun 14, 2009

sho_shane · Jun 16, 2009

So............. With what yall see here with the way the guy has it wired is the high side of the fan coming on?

ram360 · Jun 16, 2009

does the car cool down and run at normal temp w/ at speed? If that's the case your rad/wp is working fine. If it starts running hot once you stop (ie in traffic) it's a fan issue. I've seen fans that worked but were no longer pulling enough cfm to cool the car and caused the car to overheat. Just b/c it's moving doesn't mean it's working 100% is what I'm getting at.

sho_shane · Jun 16, 2009

I will take it for a drive in a min. But it cool out side so im not sure if thats the time I should be testing this.
But what if it still gets hot on the high way?

ram360 · Jun 16, 2009

sho_shane said:
I will take it for a drive in a min. But it cool out side so im not sure if thats the time I should be testing this.
But what if it still gets hot on the high way?

would prob mean you have a plugged up rad / wrong wp rotation or some other restriction that was not letting coolant thru the rad. Chance are since you replaced that stuff it's prob not your problem and most likely just your fan at this point. Once your car is up to operating temp your upper rad hose should be hot meaning your t-stat has opened. If that isn't hot your t-stat may not be opening (even new ones are sometimes bad) alot of guys test them in a pot of boiling water before installing.

sho_shane · Jun 16, 2009

The t stat does open.

I Beleave the waterpump is routed right but just incase:

What do you think?

ram360 · Jun 17, 2009

yea, that looks right.

sho_shane · Jun 17, 2009

So I just drove it like 10-15 miles down the road. As long as I keep moving it runs fine. When I stop at a light it starts to go up. Then when i get to hiway speeds it cools down. If im just cruzing slow it will get hot also.

Also I got on it and ran it hard though the gears and it heated up. But as soon as I got back o hyway speed it cooled back down.

So what ya think?

ram360 · Jun 17, 2009

sho_shane said:
So I just drove it like 10-15 miles down the road. As long as I keep moving it runs fine. When I stop at a light it starts to go up. Then when i get to hiway speeds it cools down. If im just cruzing slow it will get hot also.

Also I got on it and ran it hard though the gears and it heated up. But as soon as I got back o hyway speed it cooled back down.

So what ya think?

I think it's safe to say your t-stat/wp/rad or working as they should in that case. It's your fan .....either faulty wiring for it or the fan itself is tired and needs replacing.