High engine temp/no heat in cab.

[RSaffell]

Searched all the forums but cant find this problem. Here's the deal. Going down the road fine with cab heater on. Blowing hot. After 20 miles or so heater blows COLD air. Engine temp gauge showing running hot. Stop. Wait. Startup and run... . back to heater running ok and low engine temps... . for a while. Then engine heats up and heater blows cold. Ideas?

 

[Grey Wolf]

I suggest you fill in your signature so the troops have a better idea of the year, mileage, options, your location, etc. , etc. It helps as some years and options may make a difference on the solutions.



Just guessing but how long has the thermostat been in there?

 

[mweiman]

Are you saying the truck overheats or runs hotter than normal? Are the hoses going to the heater core hot like coolant is circulating properly?

 

[RSaffell]

Thanks GW. I have a 2006 2500 bought used at 41,000mph now has 55,000. Dont drive it a lot... . trying to save it. Just plain stock. Not sure about thermostat... . think I changed it but cant remember.

 

[jelag]

I'm guessing your low on coolant... . I've not seen a thermostat problem in all of the trucks I've owned over the years. . but have seen a few with low coolant do exactly what your sharing...

 

[RSaffell]

yes the truck does run hotter that usual. could be low on coolant didnt think of that. will check

 

[Grey Wolf]

While your checking the coolant level take a look at the coolant hose by the turbo, they have a tendency to leak. If the previous owner had a small leak there and never checked I would say jetlag was on to something...

 

[rbattelle]

41,000mph

That's roughly Mach 60 at sea level!

I'm guessing your low on coolant

That's my suspicion. First sign of low coolant is often lack of heat from the heater core, despite higher-than-normal temperatures.

My suspicion is the thermostat opens after about 20 minutes and there's not enough volume in the system to keep the radiator, heater core, and engine block full at the same time.

Ryan

 

[RSaffell]

Well you guys appear to be right. Turns out I was 1 1/2 gallons low on coolant. Filled it up and checked for leaks but did not see anything. Funny though... . was at a friends house last night and he called and said he had found a puddle where I had parked and that it looked like transmission fluid. Could that be the coolant? If so why is it not leaking now? Does it have to get hot first? I sure do like this place. Never saw so many people with so much knowledge. Thanks.

 

[rbattelle]

Factory coolant is orange, but might be mistaken for red if mixed with dirt and mud. A sniff test would tell for sure what was leaking.

Could be a pressure leak somewhere, quite possibly in one of the heater hoses on the passenger side toward the back. Common place for leaks.

Ryan

 

[sag2]

The little hose behind the turbo only seems to leak when the engine is cold.

 

[RSaffell]

Many thanks to all of you. You sure do a great service to people. Cant find the leak so guess will take it in to shop.

 

[RSaffell]

Hello again. Well, thought I had fixed the problem. put in a new radiator and thermostat also. Ran fine for a few weeks. Yesterday started running hot again. Took it back to shop. Mech said it was the little hose back by the turbine leaking. Put in a new one. Just left the shop... which closed as I left... . ran about 5 blocks and temp shot up to 250. Fluctuates 200 to 250. Shot up real fast then dropped back down to 190 and stayed there about 10 min. I have a new thermostat. Should I put another one in?

Sheesh guys this is starting to bug me.

 

[RSaffell]

PS... . was running AC this time and not heater

 

[Grey Wolf]

I would say check the water level again. There may have been an air pocket at the T-Stat then the water hit it and cooled it off again. Maybe they didn't check the level since it was the end of the day? I would see how it reacts before you put another T-Stat in it. Do you know what brand T-Stat was installed?

 

[RSaffell]

Hey hello again GW. Yeah the water level is the first thing I checked. Pulled right over 5 blocks down. Reservoir up to the mark. Shut it down and let it cool. Then drove about one mile. Temp spiked waaay up almost to redline for like half a second... then shot back down and stayed there for 5 miles or so. Have the Thermostat but am waiting like you said. what else could I check?

 

[RSaffell]

forgot, no I do not know the TSTAT brand but it was put in by a Dodge Dealer back in Feb along with new radiator

 

[Grey Wolf]

Well after it's stone cold take the radiator cap off and the fluid level should be right at the neck if not add some to fill it up and try it again. The T-Stat was probably dry until the water hit it, I suspect it will start working OK after you make sure the radiator is full. I'm guessing the the T-Stat probably came from Cummins if you got it from the dealer but there's only one way to find out, either way give it some time before you condemn it!



The T-Stats due tend to cycle a lot when the weather is cold and when you disturb the system, were do you live?

 

[RSaffell]

OK GW. You da Man. Gonna give it another hour and check. Sounds like a plan.

Thanks a heap.

Randy

 

[RSaffell]

HEy GW... . checked water level. It was down. Added almost one gallon to radiator and brought up the reservoir to the line. I live in South Texas and it was 70 degrees today. Was running the AC.