Riddle me this........ truck heat.

[Goldeneagle]

Put your hands on the input and out coolant hoses that go into the firewall to supply the heater core. If one of them is blazing hot and the other much less hot, you have a clogged heater core. If one or both is very hot blend door problem.

If both lines are relatively cool, then your thermostat is probably stuck open. If this is the case, the radiator hoses will feel kinda cool also. Remove the thermostat and check it in a pot of boiling water on the stove.

I think we have a winner! Now I'm leaning towards the blend door. I thought it was OK, but not sure now. Got home from work and checked the hoses and they are all too hot to grab. I don't think water flow or temp is the problem.

[Pstraw]

Glad you got it narrowed down. Hard to troubleshoot on the GS sometimes.

[Goldeneagle]

Going to flush it out and change the thermostat today. I may have just got a bad one last time. Also will check the blend door actuator. It is working, but maybe not moving all the way for heat. As far as the leak, I did some more research on it. Found out the intake gaskets on this model have a tendency to leak on to the top of the engine. The coolant evaporates and doesn't hit the ground. They say the factory gasket is junk. I am not changing an intake gasket in this weather! The heater core gets its water from the intake, so this may be the whole durn problem. If so, it's going to have to wait. I'll just tough it out. It sucks not being able to afford a new vehicle. At least you can work on the older ones without a degree in computers.

[doright]

I may have missed it but if you have an automatic transmission keep a close eye on the water level. I had a Chevy and the gasket started leaking and I didn't notice it. It only dropped the level a little but it was low enough to drop below the transmission line causeing the transmission to overheat. Cost quite a bit to put in a new transmission.

[Mike D]

I may have missed it but if you have an automatic transmission keep a close eye on the water level. I had a Chevy and the gasket started leaking and I didn't notice it. It only dropped the level a little but it was low enough to drop below the transmission line causeing the transmission to overheat. Cost quite a bit to put in a new transmission.

Say what?

You’re going to have to explain how the radiator has anything to do with the transmission overheating. Especially if the vehicle isn’t getting up to operating temperature.




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[doright]

If the water drops below the cooling lines going to the automatic transmission it will not cool and the transmission will overheat. Newer vehicles may not be set up like this but the older ones were.

[double bogey]

Yep, this got me in my 2008 f150. Engine never got hot, but transmission did. The upper hose was leaking at the radiator. New hose still leaked, could not make it stop. New radiator, no leak, still cannot tell why it wouldn't seal the hose. no visible cracks or defects in the tank or hose connection. Wish they never went to plastic tanks.

[Goldeneagle]

Say what?

You’re going to have to explain how the radiator has anything to do with the transmission overheating. Especially if the vehicle isn’t getting up to operating temperature.




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The transmission cooler is in the radiator.


OK, I flushed everything out, back flushed the heater core, changed thermostat and refilled the coolant. Its blowing quite a bit warmer. The temp gauge is still not getting up to 195. Next step will be fan clutch.

[Texas Grown]

Well, if nothing else, you'll have a new fan clutch too.

Drove mine for a bit this morning. Watched the temp gauge bounce back and forth for a good while. Then it warmed up a bit outside. And I slowed the truck down to 60. And the temp balanced out.
The fish are biting, and there's hogs to be kilt. Gotta go!

[Goldeneagle]

Haven't done the fan clutch yet. I did check the actual gauge and it checks OK. Maybe the sending unit is goofy. Hell I don't know. Here is a pic from this morning after a 28 mile drive to work. Remember, it has a 195deg thermostat.

[calfroper_06]

Buy you a cheap mechanical gauge set from oriellys and hook it up to check the accuracy of your stock gauages. Could be the sending unit or the gauge cluster itself. The FIL has this issue with his newer dodge, so he blocks the radiator about a 1/4 of the way with some aluminum sheet metal he has. Works for him every year.

[Goldeneagle]

Well, if nothing else, you'll have a new fan clutch too.

Drove mine for a bit this morning. Watched the temp gauge bounce back and forth for a good while. Then it warmed up a bit outside. And I slowed the truck down to 60. And the temp balanced out.
The fish are biting, and there's hogs to be kilt. Gotta go!

I'm not about to get out on 75 and run 60. That would be suicide!

[Texas Grown]

I'm not about to get out on 75 and run 60. That would be suicide!

For some reason that made me laugh.

My gauge shows about the same as your picture above this time of year.

The fish are biting, and there's hogs to be kilt. Gotta go!

[Goldeneagle]

I think I have it narrowed down to the blend door. I think the gauge is just not reading right. Before this cold weather, I ran it to full temp and checked the coolant temp in the radiator. Thermometer read about 190 in the radiator. It would be nice to have full heat inside the truck right now, but I'm not getting out there to mess with it. I'll just take what I've got and fix it later.

[knapper]

Trans fluid is run through the radiator for cooling..seperate from engine cooling..

If the engine is not getting hot enough , thermostat is most likely bad..has the truck heat ever worked?