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Overheating and Overhead display problems.

S

scubamark13

NAXJA Forum User
Location
san diego ca
I need your help, I recently bought a 92 XJ Limited that has 97k on it. I have noticed that the engine temperature gets close if not into the red range when I am on the freeway and on a steep grade for a long period of time. Then engine temp is normal when driving around town or on flat ground. I have replaced the radiator cap and coolant with a 50-50 mix and that didn’t help. I don’t think it is the thermostat or the fans because it runs fine around town. Do you think it could be the water pump isn’t moving enough water at higher speeds? Any ideas or suggestions would help.

Another problem I am having is the overhead computer display, when I bought the Jeep it worked intermittently and now it doesn’t work at all. I got a display unit from the bone yard and put it in and it doesn’t work either. All wires seem to be connected in the overhead console. Can anyone think of any other things besides the fuses that I should check?
Thanks,
Mark
 
THere are tons of threads on over heating Heeps. So, do all of the normal things such as buy a quality cooling system cleaner (the type you run for a couple of days) and do a cooling system flush. Then see what you get. From there, it depends on what you get for a response to the flush.

When I snagged this 98 2 years ago, it had several issues, over heating being just one of them.

I started the process with a good flushing and was shocked to see that the "coolant" I drained out was black. And rather chunky. After jumping the hoops, I would up replacing the radiator... Just for fun, I removed the inlet side radiator tank and found that not only was the radiator choked with dirt, the tubes were nearly completely blocked off by excess RTV that had migrated from years of bad maintenance of the T-Stat into the radiator itself.

Was not a pretty sight. Finding dirt was a new one for though... I also did the hook up the Heep to the outside faucet and back flush routine. But with a shot radiator, all that was just for practice.
 
Water pump and radiator are primary suspects.

If this were mine, I'd swap them BOTH out unless you have some evidence that they have been replaced recently.

Neither are that expensive and if you are going to keep the vehicle, doing both at the same time is not only convenient, it is money well spent.
 
Ok so I replaced Everything under the hood that I can think of and it is still overheating. Can anyone think of anything else that could be wrong with it. I can't afford much more but I need a running vehicle. I am really hoping it isn't the head. Here is what I installed on Saturday.
3 row radiator from radiator barn
Hesco hi flow water pump
Hesco hi flow thermostat housing
Mr Gasket 195 tstat
upper and lower hoses
heater control valve
heater hoses
fan clutch
serpentine belt

Thanks for your help,
Mark
 
Have you tried "verifying" that you truly are overheating with an infrared point and shoot thermometer pointed at the thermostat housing?

Long shot, but it isn't impossible that the coolant temp sensor is off.
 
I have thought about that but usually when I pull over or slow down it has cooled off already. I was thinking I might buy a new gauge and see if I get the same readings.
 
Not a bad idea. By my census, you have replaced every single cooling system component. Unless you have some sort of blockage in the block, I don't know what else could be amiss.
 
--transmission can be slipping excessively and generating more heat than the cooling system can handle-- might check the condition of the fluid, and if discolored add an auxiliary cooler

--check the AC condenser for blockage-- if the fins are folded over or a dead bird or two are stuck in there, you'd restrict the extra airflow at speed that you might be needing
 
If the fluid in the trans is bad, adding an aux cooler to it will only be a band aid at best. If the trans is so bad that it is causing the over heat issue, it needs to be repaired.

But do take a temperature reading with either a laser or an IR thermometer. Some of the (put your favourite parts house here) have them to loan. Or, worst case, replace the temperature sender. I believe you have two. one for the PCM and one for the gauge. If I am wrong, I will be corrected. Pre 97s are not my speciality...
 
My XJ already has a trans cooler and the fluid is red and doesn't smell burnt. I have bought a new temp sensor I just haven't had the time to install it yet I will probably do it this weekend. The AC condenser is clean with only very few bent fins nothing that I see on it would cause a blockage of air.
A mechanic I talked to recommended doing a block test, does anyone know what this consists of?

Thanks for your help,
 
A couple of bent fins are not going to matter much, truth be told. In the past, I have had to pressure wash the cores as they were full of accumulated dirt and, well, bugs... Unfortunately, to power wash the radiator you sort of need to at least remove the fans. Better still, pull it out so you can actually see what is what.

Let's see what you get with the new sensor. I'll "stay tuned" for the latest!
 
When I had the radiator and grill out I used a flash light to look through the fins of the condenser and it was really clean with no blockage. With the motor running i can hold a piece of paper 6 inches in front of the grill and the fan sucks it up to the grill. I think I am getting pretty good air flow through everything.

Thanks I will keep you all posted,
 
I did the block test on it and it passed. I changed the temp sensor for the gauge re flushed the radiator and I am still having the same problem. I am trying to find a good mechanic to look at it because for the life of me I can't think of anything else to do.

Any and all ideas are welcome,

Mark
 
I just had to replace my head on mine. Cracked in three places idled like crap and over heated sitting still but run like a champ on the highway and run normal temp. Do a compression test to rule that out, 3 of my cylinders run around 120 psi and the three that had cracks were 40-50 psi. Doesn't take long to do and that's the only thing left I believe you can do. Depending on where its cracked, running good or bad differs.
 
I had horrible cooling issues on my 96 when I got it. I wound up replacing everything, and I spaced the Hood for extra air flow. I also hard-wired the aux fan. All of cured my cooling issues. However, one thing I noticed while I was doing all this was at speed, the upper radiator hose was collapsing. Ibeleive it was being caused by restricted flow through the radiator. Good luck. Cooling issues are frustrating
 
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