Bing187

Hi all,

New guy here, have a problem with a 96 Cherokee sport that I bought new. Always maintained, but it has been sitting for 4 years waiting for my son to get his license. Spent a lot of hours taking interior out, welding floors, powerwashing interior, etc. Car always has (and still does) run like a top.

Finished putting it back together, started running hot. Checked antifreeze; looked like hot chocolate, boiled over. Took to a radiator shop, they detected hydrocarbons in coolant. I flushed system out thoroughly, then took engine apart. New head gasket, head surfaced and pressure tested (ok), valve seals, and hot tanked. Re assembled with new radiator, water pump, thermostat.

Ran it with coolant in it, re torqued head bolts. When I ran it, the temp gauge was buried past the 260 mark as soon as I started it. It is a new sending unit. Replaced sending unit, burped all air out of system.

Car runs and acts totally fine, no gurgling, no overheating. Have now driven it for 1 hour straight, some highway some stop and go, when shut off it doesn't gurgle or boil over. runs fine the whole time, however.....

The gauge after 5 mins is at the 240 mark, and hovers at or near the beginning of the red, creeping into the red and then back out. It stays in that range whether highway speed, or idling in the driveway. A mechanic buddy used a laser thermometer on it, and it shows 210-220 at the sending unit. Does this sound as simple as a bad gauge/ sending unit? or something I should be concerned about? I think that it does need a fan clutch, as when the engine is shut off, I can get out of the car and walk over to the front, and it's still spinning, which I know is indicative of it being bad. However, I would think that at highway speed, the fan wouldn't affect it, would it?

I appreciate any and all input; thanks in advance for your suggestions.

Mike

RTorrez1

If it's reading 210-220 with a IR thermometer it sounds like you have a bad temp sending unit. But before you start driving it make sure to change out the fan clutch or it will leave you stranded and with a lot more problems.

scottmphoto

Is your fan shroud in good shape. Most XJ's like to have it there so that it can pull the air through the radiator. Are the fins on your A/C condenser all bent up or plugged with stuff. if so, that will keep air from flowing through the radiator also.

salad

Sounds like you've taken care of it! The '96 is the last year of the absolutely annoying dual temperature sensors. The one that drives the in-dash gauge is located at the back of the head. I'm guessing you've only replaced the sensor at the front in the thermostat housing? That's used by the computer, but not the dash.

Bing187

I HOPE it's taken care of.......

I actually replaced the one at the back of the head. Twice. Removed old when I took head off. Put in new one. When I first started the engine after head gasket, radiator, et al, the gauge was maxed out as soon as I started it. Maxed out like past the 260 mark... Instantly. Figured the sending unit was bad. So.... got another one. (Not sure if there is an easy way to remove, but mine is close enough to the valve cover that I had to take VC off to get sending unit out. 2nd sending unit is the one that I described readings in first post.

My mech buddy is bringing home a scanner from work that will plug in and check computer, as I BELIEVE the scanner will get a temp reading from the thermostat sending unit, right?

Either way, my son has been driving the car for two days, it was 93 here yesterday, and no overheating, steam, bubbling, gurgling, or any other sign of overheat......

Thanks for the reply!

Mike

salad

Nope. That sending unit literally is only for the gauge.

Check for wiring problems then. Frayed wires, corroded connector, bad ground will cause that.

Radi

Are they giving you the sending unit for an idiot light instead of a gauge?