Overheating and electric fan

Ok my 88 MJ (4.0L 5-speed) has been overheating since yesterday. I topped off the coolant and it still overheats. I have a mechanical and electrial fans. I notice when my gauge hits the middle (the gauge has been off since I bought it) I popped the hood and the mechanical fan is running but the electrical fan isn't. I am assuming that is should.

Would this cause a overheating issue if it didnt run? I know it ran before so what happened. It didnt start overheating till yesterday when I went mudding with it. I made sure the radiator was clear of mud and ofter stuff. So would that be this issue or what else, like a t-stat or water pump? Maybe a temp sender or sensor or a relay or the whole electrical fan?


Thanks,

Zack

Check the condition of your tank cap.
Check the tank itself for cracks, leaks around the base.

Search here for burping air out of system.

Electric fan should come on when:

Temp reaches appx. 220 - OR
When defrost mode is on - OR
When A/C is on and compressor is cycling

There are 3 "temp sensors". 1.) The one in the radiator controls the electric fan, actually it's a temp "switch".
2.) The one in the lower driverside of the block (under and ahead of the manifold) sends info to ECU. Coolant Temperature Sensor
3.) The one in the back of the head near the firewall is the gauge. Temperature sender.

Check out the stuff ParadiseXJ mentioned.
You almost have t pull off the grill to clean the radiator right. If you use too much water pressure you flatten the fins in the radiator.
When your done shine a flashlight from the engine side through the radiator, especially the edges and makes sure the insides of the radiaro are clear (it can look fine from the front and not be. It really doesn't take much mud to cut down the airflow 25% or more. You will likely have to remove the electric fan to do it right. You might even have to separate the A/C condenser so you can clean between it and the radiator.
A good tip is to clean out the raditor before the mud dries, once it dries (depending on the mud) it can turn to near cement and can be hard to wash out. Soaking, soap and warm water helps. Cooked on clay, doesn't come out easy.
Br careful with the grill screws, they strip easy.

OK I undid my thermostat housing and I found that there was no coolant to that point. Is it the fact that I didnt bleed the system at all before I put a new coolant hose on the other week? I have a feeling it might be...

So I have the hoses off to the thermostat housing and none of the coolant from the overflow bottle was leaking out it almost seems it was plugged. Anyone know anything??

Bansheemanche said:

So I have the hoses off to the thermostat housing and none of the coolant from the overflow bottle was leaking out it almost seems it was plugged. Anyone know anything??

Click to expand...

Mine did that so I flushed it and changed the water pump. Turned out not to be the problem. Dough! waste of money and time. It turned out that the system was not bleed properly and was air locked. I fixed it by shoving my garden hose down the the radiator hose filling it til it overflowed, and doing the same at the thermostat housing. It has worked fine since then.

Oh yeah and as far as the electric cooling fan, they are known for not coming on when you need them and running when you don't. I just jumped the temp sensor on the radiator and now mine runs all the time. If that annoys you, you could replace the sensor or install a toggle switch.

sounds like an air pocket. try searching that.eace: