dragonsrule71

I have a 90 jeep Cherokee pioneer 4.0 straight 6 and I have been having overheating issues. A couple months ago i replaced the clutch fan, radiator overflow container and the hoses from the overflow to the engine. Now its overheating again. I replaced the thermostat and gasket last august. Any suggestion, ideas or helpful hints.
Thanks, Katie

djb383

The radiator is the main/primary heat dissipating component in the cooling system. Should there be a comma after radiator, as in u replaced the radiator?.....or did u just replace the radiator overflow container (the bottle)?

Pelican

Under what driving conditions is it overheating -- highway, around town, all the time, etc. What temps are you showing on the gauge?

What brand of thermostat?

Probably not your e-fan as a primary cause but is it coming on as it overheats?

You say overflow container but unless your system has been modified, you have an expansion bottle but not an overflow reservoir.

DFlintstone

You are already in good hands here...If you clarify when it overheats it might help. For instance in traffic or slow hill climb might be the E-fan or lack of a fan shroud. Is it actually boiling? Btw, always leave that bottle 1/2 empty so air in it can compress.

Firestorm500

Do you have unexplained coolant loss?

Fred/N0AZZ

????????

dragonsrule71

It mainly overheats on slow traffic in town, does pretty well on freeway speeds. Yes it was the overflow bottle i replaced, not the raadiator. I also do have some unexplained cool,ant loss. Temp strts at 100 then quickly climbs almost to 260.

djb383

Again, the rad is the main/primary heat dissipating component in the cooling system however, it is only one link in the cooling system chain. U can't afford to have ANY weak links in the chain. What has been done regarding cooling system maintenance, other than what was done in the OP?

Pelican

Does your e-fan come on?

A stock '90 system does not have an overflow bottle. I'm just trying to confirm that your system has not been modified. I have never owned an XJ with a closed system but I know that the bottle and cap can be problematic.

Firestorm500

Classic symptoms of a blown head gasket.

RTorrez1

This is your red flag. As Firestorm500 "Classic symptoms of a blown head gasket" Hopefully not but something that you need to rule out as soon as possible.

dragonsrule71

Thank you for all of the help, I really appreciate it.

Firestorm500

My advice at this point is: If you're going to keep it and fix it, pull the head and see what's going on.

If you were thinking about selling it, now is the time.

Either way, don't drive it any more in its present condition.

Good luck either way.

DFlintstone

See below.

Good idea. The E-Fan is there to provide air flow when you are not moving fast enough to get the flow through you need. Btw you can look at it, check for bugs or stuff. Maybe hose it off. (I mean the radiator and AC condenser)

I'd hold off on pulling the head just now.

DFlintstone

Two minute Head Gasket test.
A quick head gasket check. Preferably with it warmed up; remove the radiator cap, fill it to the brim, and power-brake it with the cap off. Do please be careful. In drive, pressing on the gas, of course something could go really wrong. Your foot is firm on the brake, and no-one is in front of the Jeep! Give it medium throttle and watch the coolant at the filler. If the head gasket is really shot it will bubble, or even geyser out the filler as combustion gasses shoot past the gasket into the water jacket. This won't tell you it's OK, but it can be pretty clear if its bad. Sometimes some surging is normal. If it just comes up a little or spills a little you may still be OK.