Changed t stat truck still not heating up

dpw41285

Spoolin'
The truck had a 160 in there and the gauge would barley read above the bottom mark. I changed to a 195 burbed the system and now it goes to the qtr mark and will not get any warmer. The heat blows considerbly warmer than before but still not good enough for winter. Any ideas?
 

jpalmer

New member
Re: Changed t stat truck still not heating up

your factory gauges are not accurate probably. they are known for that. just an idea
 

s_blazin

Donating Member
Re: Changed t stat truck still not heating up

either that or, i've also had in the past, the thermostat not open due to it being stuck, sometimes on new ones you have to "pop" them open to ensure they work correctly before installing. i'm havin a similar issue on my truck but it just won't read at all. i think my problem is the coolant temp sensor is bad
 

nallj92

Active member
Re: Changed t stat truck still not heating up

your factory gauges are not accurate probably. they are known for that. just an idea


X2 get a temp gun and check temps before/after thermostat to insure open close... and check temp in datamaster.
 

WyoSyclone

Active member
Re: Changed t stat truck still not heating up

Plugged heater core? Maybe pull the lines off of it and flush it... engine temp is determined by efficiency of radiator and coolant flow.... thermostat just determines when to circulate coolant....
 

dpw41285

Spoolin'
Re: Changed t stat truck still not heating up

i can touch the top hose just fine its barley warm, i did pop the stat to make sure it wasnt stuck. how do i flush the heater core.....or do i want to know? pita?
 

BoostedSUV

Active member
Re: Changed t stat truck still not heating up

My truck never reads above the 1/4 mark on the gauge unless it's overheating. According to my datamaster the 1/4 mark is right about 195 degrees. I always assumed our gauges just read low. Anything more than a 1/4 way up I start to worry about over heating. :2cents:
 

WyoSyclone

Active member
Re: Changed t stat truck still not heating up

i can touch the top hose just fine its barley warm, i did pop the stat to make sure it wasnt stuck. how do i flush the heater core.....or do i want to know? pita?

After it's been running for how long??

Remove right inner fender well.... two hoses to heater core are right there... remove hoses from core..... put a couple of hoses on core and flush with garden hose (put first few gallons in a container so pets don't get to it!)..... don't use too much pressure!
 

WyoSyclone

Active member
Re: Changed t stat truck still not heating up

My truck never reads above the 1/4 mark on the gauge unless it's overheating. According to my datamaster the 1/4 mark is right about 195 degrees. I always assumed our gauges just read low. Anything more than a 1/4 way up I start to worry about over heating. :2cents:

mine reads a quarter on the gauge... runs right at 198.. goes up to 202 or 203 with AC on, but factory manual says that's within specs..... fan engages at that temp like it's supposed to.
 

dpw41285

Spoolin'
Re: Changed t stat truck still not heating up

hmm so sounds like everything is ok then, the truck has a heater core replacement in it. i will check it with a temp gun
 

Aeroking

e.i.
Re: Changed t stat truck still not heating up

My truck never reads above the 1/4 mark on the gauge unless it's overheating. According to my datamaster the 1/4 mark is right about 195 degrees. I always assumed our gauges just read low. Anything more than a 1/4 way up I start to worry about over heating. :2cents:

x2 every word of it. My needle barely moves above the bottom mark, but TP & DM says my truck runs at 180.
 

dpw41285

Spoolin'
Re: Changed t stat truck still not heating up

had the coolant flushed and the heater core flushed. the heater core was empty....
 
Re: Changed t stat truck still not heating up

Temp cable adjusted correctly? Seems like the temp door isn't opening far enough to get enough air to flow through the core? Or the seals on the door are shot, allowing too much [cold] air to bypass the core.

Are the hoses routed in the OEM fashion? If so, the heater hoses should be getting up to thermostat temp. They will run at engine temp. They should start to get warm almost as soon as the engine is started. If they do, there's probably nothing wrong with the coolant circuits.

The upper hose outlet temp will depend on the amount of heat load the engine is under. At idle, in cold temps, the upper hose may not get that warm. Especially with the heater on. The heater can extract enough heat, that the thermostat will remain closed. In other words, the heater core is doing the job of the radiator. Especially at idle, in very cold ambient temps.

Another thing is that if just a very small piece of debris gets caught in the thermostat, and keeps it from completely closing, heater performance will suffer in cold ambient.

Get the infa-red temp 'gun'. Or wrap your hand around the heater hose coming out of the manifold. It should be pretty hot.The 1/4 mark on the gauge is proper operating location. Seems like it's running hot enough to make heat.

My guess is it's going to be the temp door.

I agree.
 

dpw41285

Spoolin'
Re: Changed t stat truck still not heating up

the hose now gets hot as hell after running i will get my gun on it today, where is the temp door adjuster thingy. my guess was i didnt have enough coolant in the system. everything seemed to warm up pretty decent last night
 

dpw41285

Spoolin'
Re: Changed t stat truck still not heating up

i know it doesnt fully travel in one direction, not sure if its up or down....i'll look tomorrow
 
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