Tetrylone

Hey all,

I'm in a bit of a stress here b/c my mechanic says one thing and I tend to disagree so i figured I'd ask ya'll 87-90 Jeep Cherokee owners what your experience is.

My cooling system is a bit different because it has an aluminum expansion tank that feeds into a plastic overflow reservoir. The expansion tank is always completely full and when the coolant needs somewhere to go when the engine heats up or cools down, it flows from the plastic reservoir to and from the expansion tank.

Temp gauge in the console keeps creeping up to the red zone. Mechanic claims the system is properly burped. Mechanic also says that it's a faulty gauge and that if the engine was overheating, the plastic reservoir would be flowing over. The coolant is flowing to and from the plastic reservoir like it should be but the damn temp gauge keeps saying its in or near the red- especially when driving up hills.

One last thing- I and the mechanic have taken laser temperature readings at both the thermostat housing and the expansion tank but the reading says 210 at the hottest.

My questions for ya'll is:

1) If the system weren't properly burped, would the coolant still be flowing to and from the plastic reservoir to the aluminum expansion tank?

2) Is it really possible that the temperature gauge has some gremlins in it?

3) Is there anything else I may be overlooking here?

Much thanks!

Andrew0257

Flow to and from is normal. Fluctuation of temp is also normal during diffrent conditions, climbs, traffic,etc. The guage itself may not be bad but the sending unit might be.

Tetrylone

I don't think this is the case. There is a brand new sending unit installed at the thermostat housing.

Andrew0257

How far is the guage going when you say approaching the red zone?

Tetrylone

Been right up to it and right up in it.

Andrew0257

Don't know? Maybe someone else will chime in?

Tetrylone

I'm hoping so!!! Thanks for your input though man!

Tetrylone

Anyone??? Beuller.... Beuller....????

a737mech

I am having the same problem right now 1996 cherokee sport red zone and also blow core plug replaced and did it agian replaced thermostat did it agian replaced pump just for heck and did it agian i did notice this last time that my elect. fan was not comming on will this cause this problem replaced relay worked then quit not came on sence.

Tetrylone

I was just reading your post- haha! Yeah. Pretty perplexing. I actually installed an after market fan controller with a potentiometer that kicks the fan on at 200 degrees and it will stop blowing while the gauge still says like 230. So i dunno.

NewXJaddict

I also have the 87 closed pressure cooling system but I don't know anything about an aluminum tank though. Mine is just the radiator and the pressure bottle. Unfortunately I can't really talk temps because mine has the idiot light. Clogged radiator or bad t-stat?