Stumped with very little heat in my TJ

[sodaktj]

Hello all, my first post but have read alot on this site.

I have read alot of different posts on this and I have learned alot, but I still have a problem. My son has had the 2000 TJ sport 4.0L with auto tranny, no AC for a couple years. It only has 55k original miles on it. I am second owner of the TJ and met the original owner. Well I wanted to do some things to it so I purchased and installed a DPG ultimate kit and some 33" tires. I have not gotten around to regearing it, but that is coming very soon. Here comes my problem. I had never really driven it before and since I have been driving it I have realized that it is really cold as in the heater doesn't really work that well. The temperature gauge at this point was running at the 2 of the 210 mark. After doing some searching on this forum and others I came to the conclusion that the coolant system needed to be flushed. I took out the thermostat and flushed the entire system and backflushed the entire system. It definately needed to be done. I replaced the thermostat with a new 195 degree thermostat and a new radiator cap. I did not replace the temperature sensor in the thermostat housing. I have a fancy SnapOn venturi vacuum and filling gadget so I am pretty positive I have zero air in the system. I drove it home that night and realized that my temperature was at 160-170 and my heat still wasn't comfortable or as comfortable from what I have read it should be. I brought it back in thinking that I need to flush just the heater core better. I flushed and backflushed just the heater core better and got some more gunk out. I have good flow coming out of both sides of the heater core. My fan is working at all levels, my selector changes to all vents is working, my heater deflector by the passenger side footwell is moving full direction both ways. This is when i realized that something wasn't right with my operating temperature as I am only at 160-170. With a temperature probe I am getting max of 110 degrees on full blast out of the defrost. I brought it back in and thought I had a bad thermostat. Replaced the brand new thermostat with another brand new thermostat, thinking that it might be stuck open. I can't find a stant locally, but I am not using a fail safe thermostat. I am still stuck at 160. I have 5V at the temperature sending unit wiring pigtail when it is unplugged and the key is on with the engine not running. I have ohmed the temperature sending unit and it seems to ohm out right for the temperature of the coolant that is running through it. The temperature on the gauge seems to be correct according to a SnapOn computer hooked up to it and also with a temp gun checking the thermostat housing, so I don't think the temperature sending unit is bad, but I do have a new one I could install. I didn't think I needed to with it checking out on the ohm meter and with it being close with a temp gun on the housing.


I can let it sit and idle in my 60 degree shop and it will not get any higher then 160 and this is with a live scan tool hooked up to it. I have two problems my temperature is only at 160-170 and the air out of my heater isn't comfortable. I am thinking if I could get the temperature to be where it should be in the 200 range then the air coming out of the heater will fix itself?????? I am stumped. Any and all advice is appreciated.

 

[Jerry Bransford]

Was that 195 degree thermostat a conventional thermostat or could it have been a "failsafe" model?

 

[M35A2]

That's a head scratcher for sure. Do you have a CEL for engine not reaching operating temp?
Unconventional but have you checked fuel mixture? Running rich will make it run cold.
I want to say maybe something wrong with the water pump impeller but while that would affect flow to the heater, it would also make it run hot so that doesn't make sense. It should definitely be running around the 200-210 degree area.

Crazy idea but maybe put a piece of cardboard in front of the radiator and see if the temp comes up. Just be sure you watch it carefully so you don't overheat the engine.

 

[sodaktj]

I think I figured it out, but I'm so releived that I had to come in and update first. So the two new ones that I installed were AC Delco 12TP1E. The parts store and the box both list as 195 thermostats. Well I decided to boil the first thermostat that I thought was bad and noticed it was opening at 160. I took it out and looked at it and it is stamped 160. Took the current thermostat out of my TJ and it too is labeled as a 160. I just had the 195 Carquest thermostat delivered which is a Stant Superstat 45359. I will be installing and keep you updated. Who would have thought that. Parts store said they will be going through their thermostats to check and see if they are all 160's or what the mix up is.

I did have the CEL for engine temp to cold. I also did run with cardboard in front covering about 80% of the radiator and it would get up to 200, but on that day it was -2 degrees without windchill. Haha.

I will update once I get the new thermostat in it.

thanks

 

[M35A2]

Fantastic! Gotta love a simple solution. I would see if the parts store will step up and give you a gallon or two of antifreeze because of their mix-up.

And at least you now know that your entire cooling system is flushed out and clean as a whistle!

 

[sodaktj]

Update......that was my problem. The two new thermostat were wrong in the boxes. The 195 is in, its operating at normal temps and the heater is hot. I actually had to turn the fan down and it got hot in there. Took it out on the interstate and the temp probe got up to 160 in the defrost vents and its 5 degrees outside!

thanks