4.0 cooling issues with new radiator

Im looking for some ides here. ive got a 98 4.0 i put a 180 thermostat in a few months ago and it ran nice n cool on the trails, maybe got up to 200-210. My radiator blew a couple days ago in the driveway, never over heated, just cracked the seam on the side tank. I put a new stock type in, 2 row and now its running hotter, 20-40 degrees and the electric fan kicks on constantly. I put a fresh mix of coolant in even a new thermostat but still running hotter then i like. i'd like a high flow pump and alum radaitor but money is an issue so thats not happening right now. So any ides way a straight swap would cause this?

Does it overheat at idle, on the highway (where good airflow exists) or both? Devil is in the details with overheats.

If it's overheating and you see "temp creep" at idle, suspect the fan clutch.

A simple radiator replacement shouldn't be in any way responsible for a 20-40 degree bump in temp.

Is the water pump the original? How many miles on it? With a new radiator, stat, and IF both fans check out, you might be needing a pump. When I had to replace the radiator on my 99 with 130k, I just put in a new pump, even though the old one was working fine as it was nearing the end of its efficient lifespan and everything was opened up with the radiator being taken out. A stock pump isn't too expensive if you do the work yourself.....

park with the nose uphill, pull the radiator cap, then start it and let it idle for a while. You probably just have an air bubble in there.

^^ i'd say possible air bubble too.

Had a similar thing happen to a 97 we had. Blew the upper rad hose off and busted the radiator. Put a new one in, but was still throwing check gauges light. Had it flushed/air bubbles released and didn't have a problem after that.

Your 98 should self-burp itself in about 3 heat/cool down cycles.

birchlakeXJ said:

Your 98 should self-burp itself in about 3 heat/cool down cycles.

Click to expand...

should, but I have had to burp a few different cherokees. It is free, and can't hurt to try.

You say that your radiator "blew" so I'm assuming it's not just a leak.

For what it's worth, and it may not be worth anything here (hope not, anyways) my 98's radiator experienced a similar fate. I replaced it and noticed increased temps and struggled to get them under control. I utimately traced it to a leaking head gasket, which was allowing combustion gases to get into the cooling system. I pulled the head and replaced the gasket, and all was well for a few weeks, then things started heating up again. Long story short - the head was cracked near the No 1 cylinder, and I replaced the head. Found it by pulling spark plugs and noting that the No 1 plug was wet with coolant when checked cold. It's been running strong for some two months now, and is running cooler than it ever has.

Hope your's is just a leak, but the fact that it is running hotter would cause me to take a look at that.....

thanks for all your input on this. The weird thing is the engine never overheated and ran cool all the time. The side tank just cracked. I will check and see is the plugs are wet with coolant though, i hope not. Its running 220-230 even on the freeway. The fan clutch seems good. Im a trying another radaitor today

Is there a proper way to "burp" thed system?

Ok installed a new radiator and its running great. Its about 95 out here in phoenix so i started off in traffic and it never got above 205-210, on the freeway with the a/c cranked it was running about 190. The weird this is the first radaitor I put in was a two row and the second one was a single row. I did notice the two row didnt equal the thickness of the single and the fin design of the single wasnt the standard zig zag but a zig zag with teeth, kinda hard to explain but it works. So maybe a two row isnt always better. Thanks to Performance Radiator in mesa to convince me to go with the single row. Thanks to everyone for your input

Good result ...

Core design is a major factor in radiator performance.

Core quality is another ....

What would have been interesting would have been for the original to be inspected - to see if it had been badly made ... with any of the tubes blocked etc ....