I do have 35inch tires, front and rear bumper with spare tire and all kinds of added weight, that is my problem my jeep only over heats at highway speeds but when crawling it stays cool like a champ. I did notice a crack on the manifold. Could that Cause rapid overheating. I also had boil overs so I know it's not my temp gauge

 

This may sound dumb. But are you 100% sure that the fans are spinning in the correct direction? If not that would cause over heating at speed because the would be spinning in the wrong direction and with the extra air pushed in at higher speed would cause the fan to slow down. The other thing I would be looking at is what is the CFM (Cubic Feet per Minute) that the elect fans put out. A lot of time the elect fans from the auto parts store do not put out enough CFM as compared to the stock mechanical fan. Just a few thing to look into.

 

Well fans keep up I know that cause they keep me cool at slow speeds. Which mean they are spinning in right direction and pulling enough air on. I'm gonna order some headers hopefully the little crack on the manifold is causing my problem

 

The motor works it's hardest at highway speeds......those tires and I presume stock gears along with the added weight for sure play a big factor regarding extra load on the motor and extra heat produced by the motor. An aftermarket cooling system that may not be as good as OE stock could be a factor as well. The fans should not be on at hi-way speeds as a running electric fan(s) can impede air flow thru the rad at hi-way speeds. At hi-way speeds there should be way more air moving thru the rad than any efan can possibly move......unless something (bumper, etc.) is blocking air flow.

A cracked exhaust manifold shouldn't cause overheating.

 

4:56 gearing with a ford 8.8 in the rear. After market bumper with winch but it is dropped below grill. I am running a champion 3 core radiator. I know a lot of people run that brand in this forum.

 

Are u saying it's always overheated at hi-way speeds (pre-mods) or just since the mods to the cooling system?

 

Not 100% correct. This I do know for a fact because I did put an elect fan in my 65 Chevy pick up and I put the wires backwards and it would get hot at higher speeds and kept cooler lower speeds because it pushed enough air to keep it cool. But the fan should have been a puller and I had the two wires backwards and it made it a pusher. Once I reversed the wires I had no more over heating problems at higher speeds. You wouldn't think that this sounds right but it can happen and did happen to me. I myself didn't think that it was possible until it happened to me.

djb is correct about this. An exhaust leak wouldn't cause a over heat problem.

 

Possible beginning of a headgasket issue? when worked hard under load a small amount of combustion gasses entering cooling system causing air pockets?

 

I did have preexisting cooling problems. I will double check my wires for cooling fan tomorrow. I did a compression check and it checks out. I am starting to think my head is leaking a little?

 

R your efans on at hi-way speeds?.......they shouldn't be.

 

They are running should I run a kill switch?

 

Efans should not be on at hi-way speeds. Most vehicles with stock efan(s) have a vehicle speed sensor (VSS) that, among other things, turns off the efan(s) above a preset vehicle speed.

 

Well I just have a temp control for the fan hooked up. Will my fans running cause over heating?

 

Fans off at highway speed where you read that ?

 

Just how fat is your girl friend. Too much weight on passenger side may be culprit.