Lets talk about temperature issues

The problems
1. - My '96 XJ doesnt heat up correctly. It sits at 105 degrees or fluctuates to the halfway point between that and 210 degrees. Most of the time it sits at 105 degrees.

2. - It doesnt blow hot air.

What Ive tried.
1. - I have replaced the thermostat which I verified as opening correctly by dropping it into a pot of boiling water.

2. - I replaced the heater control valve. When switching the HVAC controls I verified the diaphragm is opening and closing.

3. - I flushed the heater core with a garden hose both ways. After the coolant came out there was brown water for under 5 seconds. I flushed both ways.

4. - I verified the blend door is opening and closing fully with the cable as I move the HVAC from hot to cold and vice versa.

What Im trying tomorrow.
Replacing the fan clutch. I was told that if my fan clutch is bad that it would not let the motor fully warm up since the fan would be constantly spinning and that would result in my loss of heat as well.

Ideas? Opinions?

First would be to verify the gauge is somewhat accurate by pointing an infrared temperature gun at the thermostat housing while reading the gauge temperature. If your XJ has a dedicated gauge sender at the back of the head (a one-wire plug on the top left corner), then you can also compare the gauge reading to the ECU temperature sensor with an engine scanner if that is easier.

Most likely is the thermostat though. A good Standt is the way to go

What ambient temperatures are we talking about?

Forgot to add I installed a new temp sensor in the thermostat housing as well.

ehall said:

First would be to verify the gauge is somewhat accurate by pointing an infrared temperature gun at the thermostat housing while reading the gauge temperature. If your XJ has a dedicated gauge sender at the back of the head (a one-wire plug on the top left corner), then you can also compare the gauge reading to the ECU temperature sensor with an engine scanner if that is easier.

Most likely is the thermostat though. A good Standt is the way to go

Click to expand...

Im not sure how it would be the thermostat to be honest. It opens and closes like it is supposed to. Without a temp scanner I verified that the thermostat housing is hot enough to burn. Im guessing its right. I dont have a temp scanner or a code reader. I did get a Stant Thermostat.

goodburbon said:

What ambient temperatures are we talking about?

Click to expand...

?

3fifty said:

I dont have a temp scanner or a code reader.

Click to expand...

you can buy an IR gun at autozone or wherever pretty cheap, or you could find a shop and pay them to verify the readings for you

The Gauge temp sensor is at the BACK corner of the head nearest driver. One wire, disconnect it with ign- on gauge reads full scale, ground the wire- full scale other way. Sensor grounds thru threads, sealer not needed or bare min.
Sensor at thermostat is for PCM only.

If not fully burped coolant may not get high enough to give good readings. (OR good cooling!)

--Another vote for bad thermostat--

mounts spring end on engine side and point end toward radiator and vent hole up at 12 o'clock.
Get a Jeep dealer thermostat 195*F. Has vent built in.

Good Luck,
Orange

3fifty said:

The problems
1. - My '96 XJ

Click to expand...

96 XJ, while old body, is OBDII and the sole temp sender is in the thermostat housing.

By ambient temperatures, we mean "how cold is it outside?" This will greatly affect the cooling/heating of the rig.

A local early 96 and late 96 both have temp sensor at back of head. 96 a sort of a in between year first obd 2. 97 did the body changes and changed the OBD 2 setup to the later type.
:cheers:

My ,96 made in June 1996 have the two sendors.

Regardless of ambient temperature, the engine should maintain a temperature higher than 105*. I would say he have a bad thermostat; one that opens wide and stays open too long. He need to get a good quality thermostat (only OEM from a jeep deeler is good enough for me) not an el-cheapo. Other jeepers recommend the Stant.

You cannot the verify the operating temperature of a thermostat without a thermometer. I ues a turkey thermometer in a pot to check for proper operation. I check at what temperature it begins to open the let it cool and see how hot/cold it get before it is fully closed. In the Nothern winter, the closing is just as important as the opening. It stays open too long and the XJ engine run too cold.

What brand is the replacement thermostat? If it's a MrGasket that's likely your problem. Search and you'll find a few others (myself included) put a MrGasket t-stat in to "help" cooling problems in the summer and come winter time had the same symptoms you're seeing. In my case the cooling in summer issue was the radiator. The MrGasket band-aided it somewhat when it was hot but as soon as the weather cooled down the engine temp stayed low.

One thing is for sure. You can tell the difference between touching hoses that are 105 and touching hoses that are 210 like they should be. If they don't feel too hot to hold your hand on for a short time, try another tsat. If they are too hot to hold, change the other temp sensor, or even better, check the resistance of that sensor at room temperature and boiling.