97 TJ Overheating on highway

jeep
overheating
heating
wrangler

#1

Vehicle:

97 Jeep Wrangler

4.0 I6 w/AC

117,152 miles

Replaced:

Water pump

Hoses

T-stat (now has a 180 in it)

New A/C System except for the evaporator & hoses

Added an electric accessory fan in front of condenser

New fan clutch

It seems though the fans might be fighting each other because when the assy fan kicks on the rotation is the opposite direction of the drive fan. I think I might have to add an electric “Puller” fan which will also help with hp but have the same rotation. Not sure if it makes a difference though. So anyway here’s the issue:

Idling in warm weather (85-90 degrees) it’s fine, a little warm but fine. My tranny has a bad 5th gear so speeds on the hw are kept to about 60mph. That might also be a contributing factor. As soon as I take her on the hw she hits the hot zone but at the edge mostly (until I put the heat on full which sucks in already warm days). I’ve checked the plugs for a head gasket prob but they look great. I had removed the AC system a long time ago and had no problem until she went back in then the problems started. Adding the condenser in front just opened the can i guess.

Any Ideas are welcome and please feel free to ask questions, as the only dumb ones are the one un-asked.

Thank you!!!




#2

A restriction in the system, probably in the radiator. Or you have a blown head gasket which is entirely possible if you’ve been overheating repeatedly. Looking at the spark plugs will not tell you whether or not you have a blown head gasket. Take it to a shop and have them detect whether or not there are exhaust gases in the cooling system.


#3

You’re not describing your idea of hot too well. 215f (just to the right of center) is perfectly normal and so would a little higher. Are you saying you’re boiling over? Any coolant loss? Have you changed the rad cap (18lb is the OEM spec).

The colder thermostat won’t do anything productive. I’m surprised you haven’t gotten a cold for being too long in warm up mode. You will if you’re in a 4 season climate.

Can we assume that the rad has been well maintained and coolant serviced regularly?

I own a 99 4.0 5 speed TJ and a 2002 SE auto.