89 XJ Overheating

[bcmaxx]

I seem to be having a overheating problem.(1989 cherokee,4.0l, auto trans) The truck runs pretty cool most of the time except when climbing hills and summits. It goes from normal too hot in a matter of minutes.If I'm crawling in 4wd I can climb all day long without even getting close too hot. I have replaced the fan clutch thermostat and all hoses,cleaned dirt and mud from my condensor and radiator,installed a 185 thermostat,added a bottle of towcool to the coolant to no avail. I do not trust that pressurized coolant tank setup but it seems to work. At this point I'm thinking of installing a newer style rad with the normal resevoir and a waterpump, good idea? Any help would be geatly appreciated! (Big fishing trip in a few days to a mountain lake.)

[Johnny V]

If you can crawl all day and not overheat but climbing hills there is a good chance the radiator is shot. I have an '89 and have kept it a closed system as I really haven't had much problem with it in the 11 years I've had it. But I don't do much off road so maybe there is a benefit for an open system for off road?

[Jay Welch]

I had a similar problem when I first had my '89. It ran fine until I hit the highway and then it ran the gauge up. New radiator fixed the problem.

Jay in MA

[HilltopXJ]

Could also be fan clutch or air pocket in head.

[Atl XJ]

Could also be fan clutch or air pocket in head.
Read the symptoms again, its definitely NOT the fan clutch.

[Rev Den]

At this point I'm thinking of installing a newer style rad with the normal resevoir and a waterpump, good idea?

No.

No advantage to the newer system.

If it is still the original radiator, replace it...also replace your thermostat with a OEM 190 unit.
Rev

[lawsoncl]

No.

No advantage to the newer system.

If it is still the original radiator, replace it...also replace your thermostat with a OEM 190 unit.
Rev

Agree on the thermostat, but I think the main advantage to the newer system is getting rid of the crappy plastic tank that like to split every few years. Plus running the higher pressure of the open system (15 versus 6psi) makes it less likely to boil.

If you're replacing the radiator, get one for a 1992 XJ. It will have the fill cap and the same auto tranny cooler connections. If you really, really want to keep the plastic surge tank, just stick a 15-psi cap on the radiator as the plastic crap-cap on the surge tank will open first at 6-psi.

[Atl XJ]

I agree, that there's no good reason to "upgrade" to the open system. Especially, when you can get a new pressure tank and cap for like $30.

[deisenba]

So the radiator for a '92 will bolt right up with no problems? I also have an '89that is starting to run hot and was going to replace the radiator and I want to put one with the fill cap but wasn't sure how it would bolt in. I have a 5sp so I don't care about the auto tranny lines.

[ladywolf]

mine does the same thing...but i think i also need to replace all my hoses, also. so who knows, i might just decide to do the whole kit and kaboodle while im at it.

[lawsoncl]

The 92 XJ radiator I bought from radiator.com bolted right into my 89 MJ (same as an XJ from the back of the cab forward). At the time, I had a manual but I was glad it came with the auto cooler connections when I ended up swapping in an auto a year later.

[19CHEROKEE89]

some good info there. i like my closed loop system in the heap but i like the idea of being able to fill the radiator at the radiator not the pressure tank.

[Atl XJ]

91 was when they switched to the open system, not 92.