Hey everyone, did a few searches and can't seem to nail down my problem. I'll describe it as best as I can.

Things to keep in mind:

1998 Cherokee Sport, 4.0, Auto Trans ~178k miles. Bypassed heater core, new water pump and thermostat (<1.5 months)

My engine is overheating pretty bad. Here's how my heater core bypass is set up: Connected two lengths of heater hose to the two pipes on the heater core, no problems there. Connected 2 feet of 5/8" hose to 2 feet of 3/4" hose with a 5/8" to 3/4" step up connector from Napa. No kinks, all hoses secured with screw on hose clamps. My engine was running perfectly normal before the water pump rerouting coupler that I used blew apart due to a kink

Now, after replacing all necessary hoses and couplers + hose clamps, the engine will run for a few minutes at (reported) normal temperature, then all of a sudden will begin to bog down and overheat. Overheating happens about 15 minutes after starting at idle, about 5 minutes after city driving when warmed up. I've topped off the coolant after blowing the hose, and my oil shows no signs of milkiness. There is a little bit of sediment on the lip of the radiator cap opening, but I have no way of knowing if this is the original radiator. I'm going to attempt to flush it tomorrow before I go away for a few days, but does anyone know of a most-likely scenario as to why I'm overheating?

Thanks for anything you can think of.

 

Just presume the rad is shot, along with the fan clutch, and replace them both. Should be less than $150 in parts including fresh coolant.

 

So do you think giving it a quick flush with some radiator flush fluid is a waste of time then?

Edit: I'm looking on a few sites that sell radiators and some have them listed with the heavy duty cooling option. Is that part of a towing package?

 

So after giving it another look it seems that I still had to add another two gallons of coolant to the reservoir tank. No issues with overheating now but I'll keep the radiator under a microscope in the future. This thread's done!

 

A bone dry XJ cooling system holds just under 3 gals total........and u added 2 gals???????.......hummm.

 

Holy crap you were way down on coolant. Hopefully you have a 50-50 mix coolant-water instead of just adding straight antifreeze.

 

Yeah haha, guess when that hose sprayed off it sprayed a whole lot more than I thought it did..

Yeah, 50/50 premix is what I used. Pretty insane amount...but now my transmission is slipping (I think) so I'll have plenty to play with next week...

 

Tranny is cooled by the rad.....which was mostly empty.....