Hey guys,


I noticed the temperature on my XJ is a lot hotter than it should be for a stock XJ. On start up my temperatures shoot up to 210 and after driving on the highway or around town for a bit they peak around 240 (right before the red). Currently I am in Baltimore where the temperature is avging in the 80s. I drove it down from NY a few days ago with no major issues though the problem did exist at that point in time. I have had it for about a week and have not overheated since purchasing it.

Does anyone have any ideas where I can start looking? I am fairly new to this, so I am looking up information and stuff as I go. Just created a thread to get proactive about the situation. I have only owned the car for about a week.

I will add pictures of the gauge and engine bay once I get out of work.

Edit- Pictures



Temperature of XJ at the first start



Temperature of the engine after running the engine for 10 minutes.



The temperature of the XJ as I drive highway/local for however long.



Engine Bay of my XJ

Thank you

 

There's a lot of things that can cause overheating. The usual suspects would be a bad fan clutch or inoperative electric fan, collapsing lower radiator hose, stuck thermostat, or clogged radiator. I've also seen vehicles where the water pump impeller breaks loose from the shaft or erodes due to poor cooling system maintenance. A cracked head or bad head gasket can also cause overheating. (More common on 2000-2001 XJs.)

Basically anything that impedes air or water circulation would be suspect. If the radiator is clogged, reverse flushing may help.

 

You mean, like this?




That was mine a few months back. It wuzn't werkin' real good!

Cost me a head gasket replacement. It went from maintaining temps okay, to somewhat warm, then one morning went from somewhat warm to SHUT IT DOWN NOW!!! hot in just a few minutes.


I have read on here (but not verified myself) that you can replace the entire cooling system with new stuff for about $200. If the beast is new to you, that's not a bad idea. Then you know what you have.

That means radiator, pump, fan clutch, t-stat, radiator, and hoses.

 

I had a friend glance over some parts as well and we think it might have something to do with the limeish deposits (possible the prior owner mixed coolants?). I am leaning towards having a coolant flush done just to ease my worries.

I know the gasket head replacement was costly but how much did you pay to rehaul your cooling system?

 

I am going through same trouble with my 92. I have 31 inch tires with 4.11 gears, newer oem rad, new water pump, new fan clutch, back flushed system, new 195 thermo, new 16 lb cap, aux tranny cooler,all new hoses including factory lower with internal spring. Even had total die check at rad and exhaust for head gasket leaks with no trouble. I could go on,,,,,, but you get the pic! have talked to quadratec tec dpt and was told by an Zj specialist that about the only way outside of removing hood is a set of hood vents . He recommended ones by Hyline offroad louvers. Any more thoughts? About ready to throw in the towell!

I know its NOT temp sender because when it gets really hot< I can hear water BOILING! lol It actually does boil dry!

 

Start with the basics. Check your coolant, or really since this is a recent purchase, drain it flush it replace it....water pumps are fairly easy and cheap, around $40.....fan clutch real easy and cost $40....radiator $100...thermostat $10.....also would not be a bad idea to get an ir thermometer and check the temperature with that instead of relying on the gauge..or get a free app (obd2) to and check it with that


also--is your electric fan coming on?

 

Now that is one crusty water pump!!

Old-timers out there might recall that separation of the water pump impeller was a common problem on the old 1st-gen AMC V8s (250/287/327). Those used a plastic impeller press-fit on the metal shaft. They wouldn't corrode, just bust loose and suddenly no coolant flow.

 

So i checked the fans again and both the clutch and electric fan are running well at start up from what I can tell. I don't have access to a hose where I live right now so I might just have to dish out the money to have someone else do the flush.

I might change the water pump and thermostat right now since they are the cheapest parts and might look into upgrading the clutch fan. Hopefully these can drop the temperatures to more manageable levels. Is this a good idea or should I still focus on finding out the problematic area before changing out various parts?

I haven't even lifted my XJ yet so these high temps are scaring me

As far as I know, I need a Bluetooth adapter to use those apps? Got any affordable recommendations?

Edit - I think the water pump might be the real problem. How can I accurately inspect this?

 

H'mm, looks like something is going on with the oil psi also.
76 psi cold start, 76 psi hot.
Oil sending unit bad too?.... or possibly somethings up with the cluster?

I'd verify that hot coolant temp with a good IR temp gun just to be sure what you think you're dealing with is what you're really dealing with.

 

Externally all you can really check on the water pump would be leaks and play or roughness in the bearing. (You would need to loosen the belt to check the bearing.) To see the condition of the impeller requires removal and if you're going to do that you might as well just put a new pump in.

 

Maybe all my gauges are goof'd up?

There does seem to be a weird noise coming from the engine when I turned it on. Kinda like a pumping noise but I can't really explain it. Its definitely not a clunking or clattering noise so I don't think anything is loose or broken per-say. I'm not sure if that's supposed to be a normal sound either. I'm going to try to compare it to my friend's XJ and then go from there.

I'm thinking it could be the impeller disintegrated and needs to be replaced but I will take all the factors into consideration and rule stuff out as I go.

Just want to say thank you to everyone who commented so far. I appreciate the help

 

So the latest update I have on my problem is that it seems to be an issue with the gauges and not the actual temperature. I used my buddy's wired OBDII scanner and we got the temperatures from the the computer. These were more in line with what an XJ should be at. It seems that everything is showing up 25% higher than it should be. My speeds, rpm, temps, etc all show up higher on the gauges.

I'm not sure if these problems are occuring because of a third party amp/subwoofer the prior owner added.

 

That's a likely cause. Trace his wiring from the amp to wherever it goes and let us know what you find.

Bad grounds cause strange stuff to happen, and bad grounds are a general problem with these older vehicles. Add butchered wiring from an idiot installer and it doesn't get better.

 

So i looked it over with a more experienced friend. We unplugged the subwoofer from the amp and it didn't change the gauges. The wiring on the amp seems to have replaced the default stereo since after unplugging everything, no music comes from the side amps. I don't know if this is the problem though

 

That's not a sufficient test. You need to see where he made his connections, particularly any ground connections.