Water pump?

macleanflood

macleanflood

I break sh!t
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My 97 TJ doesn't appear to be reaching operating temperatures.

It's been an 1/8" to the left of 212 for a while...about the 3/8 mark on the gauge.

Decided the thermostat was stuck open. Couple summers ago I did the timing chain and water pump...Napa, Gates...pulled and inspected the thermostat then and didn't replace it because it was a Motorad and appeared to be working.

Had a hell of a time getting the water neck to seal up...took four attempts.... replaced the housing...no gasket and lots of RTV finally worked.

Similar issues this time. Got it to seal on the third attempt but now it won't get past the 1/4 mark.

Tried a new sensor. Same issue.

Though, too much RTV and I accidentally sealed off the passage to the sensor. Redid the thermostat housing this time with a gasket and a thin smear of RTV...right stuff this whole time.

Same issue.

Put both thermostats in boiling water. The Motorad barely opens at a roiling boil. Laser temp sensor shows the new Napa one cracking open around 185 assuming this HF IR gun is anywhere accurate... roiling boil on the HF IR was showing around 190.

Motorad didn't have an 1/8" hole. Drilled one in the new Napa and it's at the 12 o'clock position.

All tests have been idling engine and running it up to 2 and 3k rpm and/or thirty minute drives no heater on.

No signs of any coolant loss. Engine runs great. Ambient temperatures were as low as 27 degrees and most recent reinstall and test at 45 F.

At this point I'm guessing I no longer have a water pump?

Absolutely zero signs of overheating.

Zero trust in any of these new Napa parts. Or the HF IR gun.

-Mac

IMG20240122121157.jpg
 
Last edited:
macleanflood said:
My 97 TJ doesn't appear to be reaching operating temperatures.

It's been an 1/8" to the left of 212 for a while...about the 3/8 mark on the gauge.
Click to expand...

Have you accually hooked up a obd2 reader and see what it says your temp is… mine was like that and obd2 said temp was 200…
 
macleanflood said:
My 97 TJ doesn't appear to be reaching operating temperatures.

It's been an 1/8" to the left of 212 for a while...about the 3/8 mark on the gauge.

Decided the thermostat was stuck open. Couple summers ago I did the timing chain and water pump...Napa, Gates...pulled and inspected the thermostat then and didn't replace it because it was a Motorad and appeared to be working.

Had a hell of a time getting the water neck to seal up...took four attempts.... replaced the housing...no gasket and lots of RTV finally worked.

Similar issues this time. Got it to seal on the third attempt but now it won't get past the 1/4 mark.

Tried a new sensor. Same issue.

Though, too much RTV and I accidentally sealed off the passage to the sensor. Redid the thermostat housing this time with a gasket and a thin smear of RTV...right stuff this whole time.

Same issue.

Put both thermostats in boiling water. The Motorad barely opens at a roiling boil. Laser temp sensor shows the new Napa one cracking open around 185 assuming this HF IR gun is anywhere accurate... roiling boil on the HF IR was showing around 190.

Motorad didn't have an 1/8" hole. Drilled one in the new Napa and it's at the 12 o'clock position.

All tests have been idling engine and running it up to 2 and 3k rpm and/or thirty minute drives no heater on.

No signs of any coolant loss. Engine runs great. Ambient temperatures were as low as 27 degrees and most recent reinstall and test at 45 F.

At this point I'm guessing I no longer have a water pump?

Absolutely zero signs of overheating.

Zero trust in any of these new Napa parts. Or the HF IR gun.

-Mac

View attachment 493687
Click to expand...

I assume the water pump is not weeping?
 
I was having so many problems with my sons thermostat/cooling system, that I went with a FlowKooler thermostat. The quality in hand is very obviously superior to the local parts stores thermostats or even the Stant.
 
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It could be a bad sensor. That is what is sending the data to the PCM and you are reading via the Torque App. I'd try a $15 part before ripping the water pump off.

Is your fan clutch stuck in the engaged position? That could be a reason as well.

I don't suspect your water pump since your engine is NOT overheating, but underheating. A bad water pump would overheat the engine.
 
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mjonesjr84 said:
It could be a bad sensor. That is what is sending the data to the PCM and you are reading via the Torque App. I'd try a $15 part before ripping the water pump off.

Is your fan clutch stuck in the engaged position? That could be a reason as well.
Click to expand...

New sensor...both old and new sensor are withing a few hundred ohms of each other.

Fan clutch is good and was replaced two summers ago a long with the timing chain and water pump.

-Mac
 
I replaced my original mopar water pump when I replaced my radiator, which was probably unnecessary based on its condition after I pulled it and its mileage (~35k)…I’ve kept it as a spare. You’re welcome to borrow if you want to do some testing.

IMG_2666.jpeg
 
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Is the connector to the temp sensor corroded? What does the gauge do when you unplug it? Go to zero? That would make me think theres more resistance in the circuit than should be if you shoot the thermostat housing with the ir gun and get a higher temp.put the gun real close. The laser spreads out over distance and they don't like shiny,glossy,reflective surfaces

I had the same thermostat housing sealing issues. On a whim i used permatex high tack spray a gasket on the paper gasket last time and it works so far.no rtv boogers getting into the thermostat.right stuff didn't cure all the way or got soft and blew out,I'd never seen that before.

Why do you think the water pump is involved? It wouldn't make it run too cool
 
JMT said:
I was having so many problems with my sons thermostat/cooling system, that I went with a FlowKooler thermostat. The quality in hand is very obviously superior to the local parts stores thermostats or even the Stant.
Click to expand...

Flowkooler mainly uses Robert Shaw theromstats. They have a 340 model that dinensionally looks like it would work...however its 180 degrees and its out of stock.

-Mac
 
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macleanflood said:
Didn't think the 97 PCM had a PID for water temperature...checking now.

-Mac
Click to expand...

It does, which you figured out. Are you sure you put the t-stat in the correct direction? I'm just grasping at straws for you. I agree with others, your water pump is likely not the problem if you're under temp. As for your HF laser thermometer, have you tried to calibrate it against ice or boiling water? Just a thought.
 
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Rickyd said:
Is the connector to the temp sensor corroded? What does the gauge do when you unplug it? Go to zero? That would make me think theres more resistance in the circuit than should be if you shoot the thermostat housing with the ir gun and get a higher temp.put the gun real close. The laser spreads out over distance.

I had the same thermostat housing sealing issues. On a whim i used permatex high tack spray a gasket on the paper gasket last time and it works so far.no rtv boogers getting into the thermostat.right stuff didn't cure all the way or got soft and blew out,I'd never seen that before.

Why do you think the water pump is involved? It wouldn't make it run too cool
Click to expand...

IR gun temperatures are consistent within a few degrees of sensor temperature measured at the front and sides of the thermostat housing.

Good note on the spray gasket and that was similar to my last success using a thin schmear of right stuff on my last gasket.

-Mac
 
hear said:
It does, which you figured out. Are you sure you put the t-stat in the correct direction?
Click to expand...

That's a possibility but it doesn't appear to fit into the water neck the "wrong" way...most of the thermostat is inside the block...right? 1/8" hole at the 12 o'clock position.

-Mac
 
macleanflood said:
IR gun temperatures are consistent within a few degrees of sensor temperature measured at the front and sides of the thermostat housing.

Good note on the spray gasket and that was similar to my last success using a thin schmear of right stuff on my last gasket.

-Mac
Click to expand...

Try slowly heating the thermostat with a thermometer and see if it opens early?
Or just replace it with another 195?
 
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