Brad distler

Hey guys new to the site here so know nothing and no one yet. I have beat my head against the wall for so long fighting my 97’ xj overheating. So breakdown is 35” tires, 4:88gears dynatrac prorock 60hd rear Dane 44 front w/lock out hubs, rebuilt trans and tcase w/ correct speedo gears. New speed sensor. new ecu because old one failed. New blueprinted head, new lifters, good compression 135-145psi throughout. New sensors throughout vehicle, runs great. Flow cooler water pump, high flow tstat housing, 2 row wide tube aluminum radiator, whole cooling system is new, stock good working fans with new fan clutch, aux fan override switch, does have ac and trans cooler in front of mechanical fan. Another 35,000gvw trans cooler with fan under rear seat area under jeep. Routed outside radiator completely. 180 tstat that’s working correctly. Stant 195 failed and wouldn’t open until 215-225. Junk. This thing on freeway runs at 213 and above and downhill will drop to 180’s. Foots not in the gas hard cruising and rolls super easily with front locked out so just wheels turn not driveline. Az 110 degrees so it’s hot but slow to 45-55moh to 65-75 is all above operating temp. With 180 tstat it should try to hold 195 but it’s not even close. Stock bumpers etc just long arm kit and lots of fab work under jeep. No sliders yet either so roiling super light weight. About to scrap this 20k pos jeep so any help would be amazing.

downs

So its only overheating at highway speeds?

Brad distler

[QUOTE=downs;3560499]So its only overheating at highway speeds?[/

its overheating in general. Stopped, going slow, going 45mph +- and at highway speeds. Just a hot running mother. Always ran hot and thought head gasket may be bad which it was. So replaced it and sent head in for rebuild and casting was thin so they accidentally got into water jacket. So got brand new updated reinforced rocker area etc casting! Tstat wasn’t opening and worst of all when trans blew it blew radiator trans cooler internally, which covered up the lower radiator outlet!! New cold case 2row wide tube radiator now and new hi flow water pump because the rad took it out also. So new head rad tstat ported housing new hoses with spring in lower hose. Fans kicking *** but not enough.

downs

Has the timing chain ever been replaced?

Brad distler

Hmm no timing chain has not been replaced. Would that really be the thing doing it?!! So close to replacing that but decided I spent enough money so held off. Lol. I swear every part has been replaced on this thing besides that heater core ac system which I just smelled Freon oil last week bottom end and steering system. Literally restored vehicle at this point. But yeah would that advance timing or retard it?? Really never been looked into timing chain and overheating.

Brad distler

Sorry it has 175,000 miles on it now. Kinda important detail. Think they go bad about now huh?

00t444e

Try a factory style radiator, quite a few people have had overheating issues from using one of those high flow aluminum radiators. I am on 35s with 4.56 gears and my stock radiator, and cooling system with 180* thermostat does great. I can trail ride with the AC on and not go above 215-220* on the highway it stays around 190-200*

TrailerTrash

Does it have the fan shroud on it?

Also are the radiator hoses new? The bottom one could be collapsing or partially collapsing if it doesnt have a coil in it.

Other than that I 2nd the stock style radiator

downs

If the timing chain is very loose effecting your cam timing it could cause an overheat condition but there are other things you can do first before that. The OEM cooling system is more than adequate to keep up with the 4.0s heat if everything is working properly. All these whizbang multicore all aluminum rads are neat but IMO one of the best radiators for the XJ is the late model thick single core heavy duty/tow package radiator.

Sometimes extra coolant flow (your flowkooler pump) is counter productive because the coolant needs time in the radiator to dump waste heat. If it flows though there too quickly you can get an overheat as well.

Fan Shroud is very important as well. Without it the radiator fan pulls air from AROUND the radiator instead of through the radiator.

Brad distler

Yeah it has all the shrouds. Ran hot with stock setup so starting upgrading some parts. As far as the flowing too much water I though rad is kinda crazy talk as the flow rate is so low the water still takes 17seconds to pass a full lap throughout system. Jet skis can pass to much water over heads but the flash point is greatest when temp difference is extreme. Hence high flow pump cools more overall because moves more water over head thats overheating water with stock pump. Theory could be crap as I’m finding out now. Radiator working it’s *** odd and will drop temp 30 degrees after going over hill crest. So I really need to go back to stock for this to work!? Are all these parts BS?? I do know 4core cut sides to make tri flow set at 13degrees and 900$ worth of fans with no tstat will run jeep at 165. Not about to spend 1500$ on that system tho.

EZEARL

"So I really need to go back to stock for this to work!?"

You would be far from the first one to go back to the stock OEM cooling system and cure an overheating problem. I redid my cooling system back in 2016 using OEM parts or an equivalent. Haven't run into any situations that it hasn't been more than adequate. Keep the OEM system working at 100% and you'll be good to go.

TrailerTrash

You can check for slop in the timing chain by taking off the distributor cap then turning the engine with a breaker bar or ratchet. Turn it back and forth slowly and see how far you can turn it before the rotor starts moving

downs

Accurate statement. I've been on Jeep Forums (lots of them) for a long time. There's lots of threads out there where people have chased their own tails sometimes for years with an ongoing overheating problem, trying everything from big money radiators to big money efan setups to finally get fed up go back to an all OEM cooling system and magically have their cooling issues resolved.

As for waterflow causing overheating. It can happen. Take out the thermostat completely and the increased flow can cause an overheat. Typically the thermostat works as a restriction and slows the flow down.

What kind of coolant concentration are you running right now? 50/50? Straight water? Straight coolant concentrate?

X1997J

I did the same thing. Replaced my stock radiator with a high flow aluminum style and a high flow pump. After the upgrades the XJ was running hotter than ever. I replaced the fancy radiator with a stock one from autozone, it was only $100 with lifetime warranty. I just drove my XJ in 105 degree summer heat with no issues.

Brad distler

Man this info is just disappointing. 50/50 mix once tried 70water30coolant but scared me when ran at 225 or so. Pushing the threshold of boil points. Would hate to go back to stock being plastic end caps are scary for off-road applications. Wonder if the bronze oem toe/haul radiators are the best or just a Napa one again. Now trans is out of rad there’s no risk blowing internals up restricting water flow like before. Holes in hood don’t do crap btw. And taking underside skid plate off front bumper lessens vacuum to radiator on backside it seems. Air just goes everywhere and I think that was the first step in wrong direction. Need to make a new plate for bottom making air flow out bottom backside of engine as jeep intended.