Getting hot

The Xj is getting hot(over 210) when I run over 55 with the A/C on and continues to climb. Does this sound like a worn belt? It cools down(aound <210) when I shut the A/C and slow down some. It's got a new water pump and Radiator. It's a 93 if it helps.

how hot does it get. 210 isnt bad, the electric fan doesnt come on until around 220. a little higher is ok

It almost gets to the red and that is with the fan running. The electric fan runs fine though. I tried to flush the system to but it didn't fix it.

i think you are due for a thermostat

It sounds like you need some cooling system maintenance.

Your vehicle is 11 years old, I'd bet you still have the stock radiator in the vehicle. So I'd say your radiator is in need of replacement.

Also you did not comment on replacement of the fan clutch for the mehanical fan. The clutch generally lasts 5 years. I'd say you need to replace it also.

My radiator shop in St Louis told me if your coolant gets to 225F one time you can damage the thermostat. You should replace it and get your new one at the dealer. That heat may of also damaged your radiator cap so it does not hold as much pressure, replace it when you replace the thermostat.

If you don't have enoujgh money to do all of those things I would:

First: Change the fan clutch with one of identical size, the universal ones do not fit right. They are either too tall or too short.

Second: If that improves things then I'd change the thermostat and radiator cap.

Third: Change out the radiator. I think you have a partially stopped up radiator. You can pay $100-$150 for a brand new radiator. I installed a new Modine in my 88 XJ. I recommend you change the hoses while you do this job. I'd tell you to get the upper and lower hose at the dealer, figure on $40 for the pair. The hoses are well made, have the anti-chafe, and the lower hose has the spring to prevent it being sucked shut. I'd also throw on new hose clamps. Take the hoses to your local hardware store or home center and buy the right size clamps for each hose. I hate the 2-4 inches of hose band haning out there, just looks unprofessional.

I have done all of this and it not bad. It to be epected wth an XJ over 10 years old.

And before you remove anything drain the system, refill with water and add a bottle of Prestone 7 hour flush. The flush will remove alot of crud inside the engine and will do it better than the 15 min flushes that more or less sand blast the passages, the 7 hour stuff chemically removes stuff. Also sweat a bit more and turn on your heat so the heater core gets cleaned also during the process. When done with the cleaner install the prestone back flush kit in the OLD hoses and back flush the system to get the crud and cleaner out. THEN install all the new stuff. I use Mopar dealer supplied coolant and mix it with distilled water NOT tap water, after all I just got all the minerals out why put them back in again.

Just go straight for the radiator. Had the same problem last summer. Changed the thermostat, the electric fan sensor, tried flushing the system but still red lined. I boiled over at one point in late June. Changed the radiator and never gone over 210 since. I would change the thermostat too though, its only a few bucks.

If you are overheating above 55 with a new radiator and waterpump, something is major wrong. XJ's tend to overheat more often at slow speeds. The fans have nothing to do with it, since it happens at speed. I suppose if the belt is really loose, it could slow down the waterpump enough to cause a problem. If the work was recently done, you may just have too much air in the system. The thermostat is another possibility, although I would think it would overheat at all speeds with a bad one.

Fred

Fred said:

If you are overheating above 55 with a new radiator and waterpump, something is major wrong. XJ's tend to overheat more often at slow speeds. The fans have nothing to do with it, since it happens at speed. I suppose if the belt is really loose, it could slow down the waterpump enough to cause a problem. If the work was recently done, you may just have too much air in the system. The thermostat is another possibility, although I would think it would overheat at all speeds with a bad one.

Fred

Click to expand...

If the belt was loose enough to slip on the water pump pulley, it would slip even more on the PS pump, and on the alternator. (They generate much more drag on the belt than the water pump.)

The overheating at road speed is a classic symptom of a radiator that is too plugged up with crud to dump the heat into the air properly. Given that you have the original rad. at 10+ years, it's a safe bet the rad. is in need of replacement.

IF you decide to change the radiator you will be at a place you can do a lot of maintenance on the front of the engine with more working room.

On the belt issue I'd replace it if it 4 or more years old. I got my 88 XJ in 97 from my Dad's estate. I drove it some and in 2000 the fan belt broke. It was the factory belt. It caused me to overheat and that when I removed the 12 year old radiator.

I recommend you also change the fan belt. I am into doing maintenance while it is easy, kill more than one job at once. We have talked countless times on here about the Kriket II belt tension gauge from NAPA. Get the model that goes to 300 lbs since the belt tension for a new belt is 180-200 lbs. There is a model which does not go to 200 lbs but will work if you were doing a retightening which is 140-160 lbs.

I also recommend you replace the idle pullies, the cost $10 to $20 each. I'd also spin the other power accessories to verify they turn smoothly. You already did the water pump so you may have a new fan belt. If your belt has been squeeking I'd recommend you get a new belt since that belt is glazed from the squeeking.

Also the harmonic balancer can fail anytime after 100,000 miles. You may also want to change that out while you have the radiator out. You will have more room for the puller to work.

family XJ said:

The Xj is getting hot(over 210) when I run over 55 with the A/C on and continues to climb. Does this sound like a worn belt? It cools down(aound <210) when I shut the A/C and slow down some. It's got a new water pump and Radiator. It's a 93 if it helps.

Click to expand...

Come on guys! He's told you he has a new radiator so why are you suggesting that he replaces it? Did you miss it?
Overheating when driving on the highway either means there's not enough air flowing through the radiator or not enough coolant. At 55mph, there's enough ram airflow to make a fan unnecessary so replacing the viscous fan clutch will do absolutely nothing. If you have a winch or spotlights that are blocking airflow through the radiator, you might wanna move them.
Otherwise your problem is not enough coolant flowing through the radiator. Your radiator is new but it's just possible (but unlikely) that crud from inside the engine's coolant jacket could have blocked parts of the radiator core. A good flush might help but like I said, I think it's unlikely.
It's most likely that your t'stat is sticking and not opening until above 210* so I suggest you replace that as your first line of attack. You can flush the cooling system at the same time. Also change the radiator cap if it's old and your problem should be solved.

Dr. Dyno said:

Come on guys! He's told you he has a new radiator so why are you suggesting that he replaces it? Did you miss it?
It's most likely that your t'stat is sticking and not opening until above 210* so I suggest you replace that as your first line of attack. You can flush the cooling system at the same time. Also change the radiator cap if it's old and your problem should be solved.

Click to expand...

OOPS. I must be blind. Dr. Dyno is right, with a decent radiator, I vote for the thermostat next.