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engine temperature low

90xj06

NAXJA Forum User
Location
Peabody, MA
any reason why a engine wont get fully up to temperature? is a renix era and the ecu is showing a spread of 169-175 with peaks of 183. its got a new water pump and thermostat. im pretty sure i got all the air out of it.
 
Bad T-Stat stuck open or out of spec opening too soon
 
How, with what and where, did you verify the actual temps?
 
After I redid the water pump and t-stat in our 90s HO 4.0 the temperature sits considerably lower on the gauge, I haven't checked it with a thermometer, but I assume it hovers right at the t-stat temp since it's the same in summer and winter. If yours is really hovering 170-175 I'd think it's a open t-stat.


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And do not trust the dash gauges to read absolute-true temperatures. Verify them at the T-Stat housing with an IR gauge tester.
 
is a renix era and the ecu is showing a spread of 169-175 with peaks of 183. its got a new water pump and thermostat. im pretty sure i got all the air out of it.
If you are taking this reading from the ECU sensor, using a scanner: Test and/or change the ECU Temp Sensor.

I used to maintain a friends' vehicle, it would not pass emissions. After a trip to La Casa de Flores (and his MT-2500), we found that the ECU temp sensor contradicted every other method of measurement. After replacing that sensor, the ECU entered closed-loop and passed emissions.

For the sake of brevity, that vehicle had been overheated prior to the ECU Temp Sensor failure.
 
I will swap the sensor out. And yes I was reading using an mt-2500. I'll try changing the thermostat again after if that does not fix it
 
I will swap the sensor out. And yes I was reading using an mt-2500. I'll try changing the thermostat again after if that does not fix it

Did you compare the reading to an infra-red thermometer on the thermostat housing?

Is the gauge also reading low?

I only use Mopar thermostats anymore.
 
the dash gauge mostly reads low and will swing up just shy of 210 and swing down. would air in the system cause this? i would think it would show hotter with air?

ill try and check the housing with an infrared. i just swapped this engine from one jeep to the other and the problem seems to follow it. and i think its the cause of the less than hot heat.
 
i dont think i have a blown head gasket. im not loosing coolant and i just swapped spark plugs and non of them looked suspicious. infact they all looked great.
 
the dash gauge mostly reads low and will swing up just shy of 210 and swing down. would air in the system cause this? i would think it would show hotter with air?

ill try and check the housing with an infrared. i just swapped this engine from one jeep to the other and the problem seems to follow it. and i think its the cause of the less than hot heat.

This whole "burping" the system etc/air pockets is a bunch of hooey.

Get a factory stat and be done with it.
 
195 is the correct T-stat.

Flores and I did use an IR thermometer to check temps. When compared to the dash gauge, and the MT-2500 read out, the IR readings were much closer (10-15 degrees) to the dash gauge. The MT-2500 was reading around 160 degrees.
 
What was the outside air temp in your area when the temps were taken ?
The recent cold air in my area(Va-in the Valley)has been in the teens.My 96 w/195* stat will run at 210* in most normal weather. Recently it will take 20 min @70 mph to get to that 210*....of course the heater is at full blast...
 
It's been in the low 30s upper 20s here and after an 1:30 drive it still stays around that area. I did see it go to 187 then it dropped back down to 163. What's a good brand of tstat.
 
You can change parts until the cows come home and still not know what the actual temperature of the coolant is.
For less than twenty bucks, you can buy a infrared thermometer and find out what's up.
https://www.amazon.com/Etekcity-Las...61062&sr=8-1&keywords=Etekcity+Lasergrip+1080
It's a very useful tool that you will find lots of uses for.

I tried four different temp sensors in my 01, including a Mopar, before finding one that agreed with the thermometer.
You can verify the thermometer's accuracy by checking the temp of boiling water, making the correction for altitude.
 
You can change parts until the cows come home and still not know what the actual temperature of the coolant is.
For less than twenty bucks, you can buy a infrared thermometer and find out what's up.
https://www.amazon.com/Etekcity-Las...61062&sr=8-1&keywords=Etekcity+Lasergrip+1080
It's a very useful tool that you will find lots of uses for.

I tried four different temp sensors in my 01, including a Mopar, before finding one that agreed with the thermometer.
You can verify the thermometer's accuracy by checking the temp of boiling water, making the correction for altitude.

Good idea.
 
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