So I was outside this morning putting in a new head unit because my sub and amp didn't sound good with that touchscreen one, it was all ghetto and weird. Anyway, the heat worked good and only from defrost this morning when I started it. I turned it off, messed with the radio wires, then I turned the truck back on...no heat. just blows cold. Then I thought maybe the t-stat is shut? I let it sit on for a little bit and it started to overheat. So does that mean it needs a thermostat? I've never worked on a diesel and I don't plan to, I'll have a shop do it most likely.
Are there any other causes that would make the heat blow cold and make the truck to start overheating?

 

You say it's a diesel? What year?

But I believe even if the thermostat doesn't open, coolant still should be circulating to the heater core, and you should have some type of heat. I would make sure the water pump is spinning, and if it is the thermostat may be the cause. A new water pump and thermostat may be in just a needed maintenance items depending on how many miles are on the pickup. The water pump and thermostat are both easy to replace on the 2nd Gen Dodges, two bolts and you have the water pump out, and move the alternator over and three other bolts and the thermostat is out. You could do it very easily, just make sure when you replace the thermostat that you get new gaskets and the old ones match the new ones, and especially the order at which they are placed in the housing.

 

1998.5 24v, I haven't really checked if the fan spins or not, it just started overheating then I went back inside.

 

He just got it. Truck in signature is old one.

Working on diesel isn't any different than gas. You just get alot dirtier!

Might need to remove and powerwash the radiator from puke bottle sludge.

 

And it smells worse......

Let the engine cool COMPLETELY, and check coolant level.

 

DIESEL IS THE BEST SMELL IN THE WORLD!!!!! ARE YOU CRAZY??

Then gunsmoke,

then two-stroke exhaust. And if you disagree, I'll ban you!!!!

 

LOL. I agree with the gun smoke though, so long as it is not from Qwik-Start canisters on B-52's.....

 

Did you fly those?

I grew up a truckers kid and always wanted a diesel truck. My gasser was just a phase in my early 20s but she was so good to me and cheap that I've kept her. But my heart skips a beat whenever I hear a sweet 24v and stick go rattling by. And the smell is heaven....too bad I can't ever get one anymore.

 

No, I sat in a pickup truck and watched them rust. (Security Police) Of course, when there was an "alert", everyone went nuts, and 6 B-52's fired all eight engines (each) at once with the 'quik-start' cartridges. Essentially, a five pound coffee can filled with gun powder..... One for each engine...... From the horn going off, to the first buff rolling out, was less than 3 minutes, and smelled horrid. (not to mention, everyone had a bad case the next day, from breathing all the fumes. )

 

I remember when we were doing a drill in Japan and I smelled the F-22s as I was performing a HALO jump