Hot 4.0?

I have a 1997 XJ put a new 4.0 in it and it seems to get really hot after only a few minutes of idleing. I just bought the thing with a bad engine and got the new engine in it. When i was filling up the radiator it seemed like it was taking water slowly so i stuck my finger in the filler neck and there was brown sludge in it.

The heater hose's that run to the heater core get very hot! The upper radiator hose dont get as hot as quick and the radiator is comfortable to put your hand on. I am wondering if the PO might have toped it off with Dexcool at one point in its life or something..... The XJ has idiot lights, no gauges. So i cant tell how hot its getting but you cant keep your hand on it for more than a second.

I bought some Zerex super cleaner to run through it. If Dexcool sludge is cloging up the radiator do you think this stuff will remove it? I called a radiator shop they want $70 to boil it out.

I would take it to a rad shop to get a flush an rod out done, this will also clean your heater core out too

Trust me if it's plugged it's a waste of money to have it serviced. With the cheap cost of radiators these days, along with the relative simplicity of installing a new one, that is a much better idea because chances are the radiator you have now is in rough shape and won't get much better.

I'd strongly suggest installing an actual gauge, those idiot lights don't come on until it's too late, which is worthless. I'd also try running that cleaner through it, mainly to clear up the block if you do decide to get a new radiator.