Another cooling issue

1994 Sport, water pump bearing failed.

Replaced and still overheats. I have read that there is no need to bleed the system with the 1994 because it's not a closed system. Also that if it's heated up/cooled down a few times the air would escape. I have driven mine several times and it still gets hot, have to drive with the heat on to keep it out of the red.

I am assuming that by heating it up/cooling it down that the air would come out through the rad cap into the overflow tank. Is it possible I have a bad rad cap not allowing it to escape? Or do I need to bleed by removing the coolant passage plug on the back of the head, with the front end in the air? When I first drove it after the w/p install I pulled over a few times and R&R'd the rad cap and it cooled down a lot.

Thanks,
Turtle

p.s anybody got a red front passenger door in the MN metro area, minimal rust is fine. 4 door.

I usualy squeeze the top rad hose to get the air out (burp) also check all the fins on the rad and make sure you did'nt flatten any by mistake. I use a small flat head to straighten them.

You could have a bad radiator cap so you might as well replace it since it's a cheap fix. It might just work.
Did you replace the lower radiator hose at the same time as the water pump? If not, your old hose could be collapsing under suction from the pump because the spring inside it has rotted away.

What about the thermostat? New, Old. Stuck open, but not enough etc...

I'll try the cap, your right it is a cheap fix.

But had no overheating problems before. The water pump bearing failed and I figured it was air in the system because there was no issues before the w/p failure.

Thanks for your help

Where did you get your new water pump, and did you compare it to the old one before installing it?

The problem sometimes arises that the Jeep 4.2L engine did not use a serpentine belt, it used the old style vee belts. Because of belt routing, that water pump rotates in what can be called the normal, or "forward," direction. Because of the way a serpentine belt is routed, the water pump on a 4.0L rotates in the reverse direction.

BUT ... because the blocks are the same, the 4.2L water pump will happily bolt onto a 4.0L block. It sits there and spins around, but the impeller doesn't push any water through the system because it's configured to rotate in the opposite direction.

If you still have the box or the receipt, double and triple check the part number to be sure it's the right pump for a 4.0L, not for a 4.2L.