xj over heating

[dan]

pick up a 98 xj yesterday it over heated on the way back to my house the temp gauge was moving back and forth from cold to over heating and today the gauge isnt moving, so my question is, is this common or do i need to go thru the cooling system until i find the problem. this is my frist xj so i dont know thee normal problems any info would be greatly apperciated. it has the 4.0 if that helps

[WrenchMonkey]

I know the old renix systems a lot better than the new-fangled stuff, but the cycling from cold to hot makes me think "sticky thermostat."

'Course, if the gauge isn't working at all now, I'd certainly start there. Maybe the "cycling" was just a function of the dying gauge/sending unit.

Robert

[blazerbrad]

What driving conditions was this occurring at (freeway, cit, etc...)? Did you verify it was actually getting hot (boiling over/steaming) or just going by the gauge?

Huge fluctuations in the gauge reading like going from full cold to full hot pretty quickly usually make me think something is wrong with the gauge, wiring, or temp sensor. An engine can only heat up or cool down so fast.

Another quick check would the coolant level. If the level is really low, and pending the position of the temp sensor, it can actually go from reading the coolant to air pockets.

If the temp fluctation is smaller than I would be suscpicious of the thermostat.

[1bad96xj]

I've always heard it's because the XJ's have such small radiators. Mine never gets to the overheating point, but it's constantly running hot. Everyone I wheel with that run XJ's are also like this. But like the previous post said if its the temp gauge isn't working at all now I would start at the thermostat

[dan]

When it over heated I was in stop and go traffic it did boil over but the cap was just sitting on it not tightened down ( shohave checked before leaving but 45 minutest drive didn't overheat so didn't think about it) after I filled it back up and tightened cap only problem is gauge

[Coppertop]

Sounds like the electric fan is not working...Make sure both cooling fans are running.

Good Luck

Nick

[1bad96xj]

If your fan isnt working correctly you can bypass it using a lil bit of wire so it works all the time. This is what I did so I don't overheat as easy when sitting on trails waiting for ppl. Very simple and takes a few mins

[itbrokeagain]

The fan should come on when the AC is on or when it reaches 213ish.

Check into a bad guage. Mine go crazy every now and again but if I shut it off and turn it on they are ok.

[itbrokeagain]

If your fan isnt working correctly you can bypass it using a lil bit of wire so it works all the time. This is what I did so I don't overheat as easy when sitting on trails waiting for ppl. Very simple and takes a few mins

The Zj fan clutch upgrade is well worth it.

[dan]

It was the wiring from the sending unit quick easy fix, are there any common problems with xj's I should know about there isn't any other problems with as far as I know yet but only had it since Tuesday