Hey guys, I've got a 1998 Dodge Ram 1500 with the 5.9 Mag.and my heater isn't working as well as it should. Now it isn't a thermostat because the pickup stays up to temperature where it should without overheating and the heater does blow warm/hotish air but not very well. I can hold my hand against a vent and feel hot air but about a 1' away, nothing. I live in Montana and I understand that at cold temperatures it takes a while to warm up but I let my vehicles run about a 1/2 hour before I go to work and even then the pickup cab temperature is barely warmer than outside. The windows will defrost in time but even after warming up for a 1/2 hour, then driving 20 minutes at 75-80mph, things still aren't warm enough to shed a coat. Any ideas? And just fyi, the ac works great.

 

How is the coolant level?

Unfortunately, on these trucks, the heater core is quite adept at trapping air. That seriously compromises efficiency. Need to burp the cooling system, with the radiator cap being the highest point, not the heater core. Either that, or try and back-fill the heater core via the outlet hose. (the one that goes to the steel tube on the water pump.)

 

Coolant level is good although I have had to top it off before, but never anything excessive but I may have to see about the air in the heater core.

 

When was the last time the core was flushed?

 

No clue to be honest. I bought it a couple years ago and only put about 10,000 miles on it so far.

 

Hello,
So HeyYou, to back-fill the heater core you would disconnect the heater hose from the steel tube on the water pump and add coolant to the heater hose? I am having the same problem as Chetmotox. I have tried swithing the heater hoses to the opposit tubes on the heater core. That got me a bit more heat, but still not real hot.

 

Switching the hoses still leaves the same problem. The heater core is the highest point. (where the lines go in.) Still lets it keep its air.

Keep in mind, when you pull the hose off the pipe to the water pump, coolant is going to flow out of the steel pipe as well. I just stuff a cork in it while I was dinkin' with the heater hoses.

 

So I burped the system for over an hour and then borrowed a friend's thermal imager to check temperatures.




Any idea how hot these should be? Remember that it is about 32 degrees F during this so there will be a touch of heat loss through the hose. After the letting it run for an hour then driving home 20 miles, it still doesn't get as warm in the cab as it should.

 

Is the fan not blowing hard, or is the temperature lower than you expect? Just trying to clarify before you tear the whole truck apart.

Edit: Just saw your picture post (cool toy). You can disregard this post

 

Well, you are getting good heat transfer at least. Trouble is, there is likely still an air pocket in the heater core. If you look at the hose routing, you will see how this can happen. Need to give the air a path to escape the core. According to theory, if you put a flush T in the outlet line, start the engine, crack it open a bit, it *should* allow the air to escape, and make your heater FAR more effective.