So its a 96 cherokee that has I assume is a over heating issue. My ggauge reads almost 260 it sits just below it. But it doesn't boil over..... my diagnostic comp says there is a high voltage issue with my coolant temp switch on the goose neck thermostat housing. I repplaced that sensor along with replacing the temp sensor on the engine block near the fire wall that's the one that controlls my gauge. And itt still read almost 260 so I thought my gauge was faulty so I changed it with one from my other cherokee. Still 260. My elec fan doesn't run all the time and only turns on when I am putting stress on my engine so iit would raise the temp. My diagnostic tool says my coolant is at about 180 to 190 and that sensor is on the goose neck. But what gets me is that it should be boiling over at that temp.....my gas mileage went into the toilet as well. Also I have a crack in the block up front that it spits out some coolant but not a lot. it all started when I refilled my a/c one day it over heated and spit out everything onto the ground. So I'm at a loss I even flushed. Evry hose. Both radiator and heater core. Changed the water pump and removed the thermostat. So anybody have any suggestions???

 

is your temp sender that you replaced from autozone under the duralast/wells name?

 

Coolant with a 50/50 mix and combined with a 16 lb rad cap will have a boiling point north of 260F.

 

My temp sensor is from auto zone and yes I think is a durlast/wells. And I'm running pretty much 99 percent water with a 16 psi cap

 

Isn't there 2 temp sensors? One on the tstat housing and one on the rear of the block?

 

Yes

 

Just so we are on the same page:
1. A coolant temperature sensor for the PCM is in the thermostat housing.
2. A sending unit for the dash gauge is located in the cylinder head.
Right?
Now from a cold engine start does the dash gauge begin at the far left of the scale and end up about 260° when warm?

 

Yes that is all correct. And yes to it starting all the way from the left

 

Also I turn my heat on from a cold start. It doesn't even get warm until the gauge says the engine is running around 260 for a few minutes

 

For the gauge sending unit it looks like AZ has like 6 different part numbers that vary between 24 - 42 ohms @ 220°.

 

What does that. Mean?

 

I'm thinking with more resistance in the sending unit, the lower the dash gauge would read. Do you have a VOM? If so warm up the engine to operating temp shut it off & see what kind value you get between the sending unit terminal & a good ground.

 

100% water and a properly functioning 16 lb cap will raise the boiling point to +/-260F.

 

Sorry I am late to reply back. Unfortunately the reading you are getting just below the red line is your new "210". I put over 12 hours of research and went through 3 different wells temp sensors. I verified everything was working right (gauge, actual engine temp, resistance at the sender, etc) and was stumped.

After calling and getting the ohm range my sensor needed to be in from wells, it checked out. I called the dealership to see what the specs were for their oem senders and they could not dig it up for me. They did however say that it is not uncommon for an aftermarket sensor to be slightly different for whatever reason.

You can still tell if you are overheating by the gauge going farther than your new normal, it just is off for whatever reason. The best suggestion I can give after my hours and hours of research-try a sender from napa that is manufactured by someone other than wells. Even the ones from the dealership (they want $80 for it lol) have a chance to be a little off since it is only a single wire unit.

 

Do you think an after market temp. Gauge would do the trick?