Replacing 94 YJ Cooling System 4.0L

Just ordered a 3 core all metal copper rad, all new hoses, clamps, thermostat w/ gasket. I also want to replace the water pump and tube that goes to the heater core. All the hoses and clamps are OEM. I currently have original hoses and clamps w/ 193K miles so I'm happy with them since they don't cut the hose or put too much pressure on the core and water tubes. I was going to go with a new water pump from the dealer but I have heard that re-man water pumps are better than new. So I am going to my local NAPA and order one. Is there a better water pump then the original out there? I have the I6 w/o AC and a serpentine.

I also checked my fan clutch by shutting off the engine and watching to see if the fan would still spin but it went off right away.

The thermostat housing looks tired but it is still working okay with a little coolant color leaking and boiling out of the bottom, above the pump.

The radiator is shot. It's the original aluminum with the plastic tanks. The fins are rotting off holds water but is leaking slowly when the seams get hot and cold.

What else should I be looking for in replacing the coolant system. I tested the guage by shorting out the wire off the temp sensor and that pegged the temp meter. The expansion tank looks okay IMO. I will also buy a new radiator cap.

Is the original thermostat okay to run or should I use a cooler one? What is the temp where the computer (if any) would sense that the engine is running at normal temp and using the proper mix and feedback. I am guessing anything above 160?

I think this is considered a closed system because I have an expansion tank?

It doesn't look like a hard job and I might have to get some new radiator hardware bolts and screws to install the new one. There are extra in and outs which are probably for AT or oil cooling but it should be seperate from the main core. I will leave them open and they should be okay.

Reply to
Peter Parker
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Good move, Chrysler's plastic tank radiators are crap. Mine went south at

Reply to
Jerry McG

First thing I will do is flush the system.

I am replacing the serpentine belt. When I am ready, I will blast it all down with PB blaster and let it sit before I loosen up anything.

I'll cut off the old hoses and I also use channel-locks to take the clamps off.

Too bad about the thermostat. :) I will check to see what kind was being used.

Reply to
Peter Parker

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