recce

I have a 1990 cherokee with the 4.0 six cylinder 230 thousand miles. my heater control valve broke and leaked all my fluid out causing a major overheat. I bypassed the heater core and ran the hoses directly to the coolant tank but its still heating up. does the heater core have to be hooked up? or have I blown that motor?

cruiser54

No. The heater core doesn't need to be hooked up
Good chance the overheat is caused by the pressure cap not sealing on the pressure tank.

How does the Jeep run?

recce

yes the jeep still runs good. i did notice the cap was cracked. I will try replacing it today and let you know if it worked. Thank you so much!

TrailerTrash

If you just topped off the radiator and didnt bleed the system, there could be air pockets trapped.

cruiser54

if your radiator is old, consider replacing it with a NR2802 and go open cooling system.

recce

so i replaced the cap and tightened the hose on the bottom of the coolant tank. it stays cooler longer now but eventually it heats up. how do i bleed the system?the radiators only 2 years old.theres no water in the oil or coming out of the exhaust.

awg

If you had a "major overheat"...and it still overheats, I would pay the small cost of testing for the presence of combustion gasses in coolant, or coolant in oil, in case your head gasket has been compromised

If so, you would expect to use a bit of coolant, check for presence of cream on oil cap inside

cruiser54

Many times after overheating, the cap doesn't seal well on the bottle because it has heated and distorted.

J M

The thin hose that runs from the radiator neck, to the coolant reservoir bottle, was clogged. Years with one line above the 210 on the gauge; now showing a steady 210. Best regards.