So, our first cold morning of the season here in Oklahoma... 33 degrees with an 18 degree windchill factor. I went out and started the '99 D2 about 10 minutes before I left for work to let it warm up. I went ahead and turned the heater on so I'd have some warm air flowing once I got in it. Well, my heater never got warm.

The truck was running fine and UG showed my temperature a little above average for me. I'm usually running around 198-199 while driving, but this morning I was up around 210-212 while driving. I'm at work and haven't had a chance to check anything. I'll have to do that this evening. My guess is a thermostat issue, low coolant, or something wrong with the heater. The way my stuff usually goes, I'm guessing it won't be an easy, simple fix and I'm going to have a colder ride tomorrow morning (temps are going to be down to 18-20 degrees).

So, your thoughts? Ready... GO!

Edit** I should mention that I'm going to replace the coolant reservoir. When I installed the lift kit, moving the reservoir around, I noticed it had some very brittle parts and I'm afraid that it may be damaged or leaking. So, I'm going to replace that in short order. But, I have not noticed any leaking and temperatures have been fine up to now. I have had the heater on and off over the last few weeks with the cool morning temps and the heater has been ok.

 

Heater core clogged?

 

Don't know. How do I check that?

I had air flow from the vents (defrost, main vents, and floor). Turned the air off and on a couple of times and adjusted the fan speed. It did seem that when the air was on low, it had a little warmth to it, but on hi speed, it was all cool air.

 

Disconnect the inlet/outlet lines to the heater core on the firewall. Take a garden hose and put it on the inlet side of the heater core. See if water flows out the outlet side. If not, try flushing out the obstruction by flushing from the outlet side.

 

I use this for flushing. I am sure that there is more job specific stuff, but I had a dishwasher connector laying around

 

My bet is low coolant.

Running warm, you opened your heater, air lock or air in heater. first thing i would do is add coolant, throw in a small bottle of kseal, run the care for a few miles, keep an eye on the temp and the heat. if it still sucks or you wan to go crazy, drain it flush it, fill it and still kseal it cause if it is low on coolant it leaked somewhere.

 

Thanks doyle! That will be my first check. I'm going to stop by the auto store on the way home and grab a bottle of coolant. I'll check my levels when I get home and into the garage. I'm guessing kseal is a leak stopper? I'll check into that too.

Thanks for the replies, fellas! I appreciate it.

 

Well, added coolant and let the truck run for a few minutes while sitting in the garage. I didn't drive it. My temps came down to my normal idling temps, but I'm still not getting any hot air from the heater.

Also, why looking around, I do have a leak in my cooling system somewhere. One place, there is a slight leak with the bleed screw on the top hose across the radiator, easy fix (either just the plug or a new hose and plug). The main leak is somewhere on the front of the motor, behind the pulleys and belt. I saw some coolant on the front of the engine, but couldn't tell where it was coming from. It was only dripping with the motor running. When I shut it off, it stops leaking. It's a pretty good drip too, one drip about every second under the truck.

Please tell me this isn't a major issue. I'm afraid it is.

 

Water pump?

 

Update... my heater is now working! I either didn't let the motor run long enough last night, or I just needed to drive it to really get the fluids flowing, but with the drive into work, the heater worked.

So, now the downside... I still have a coolant leak from somewhere at the front of the engine. From what I can tell, it's coming from the front, directly behind the belt/pulleys. So, I'm guessing one of 2 things... as 909wheeler offered, the water pump, or, it could be the much worse of the 2 and be the head gaskets.

I would believe, a sudden change like this would probably be the water pump. I would think if it was the head gaskets, that I would notice a slower leak over time and not a steady drip like I'm getting. It only drips as the motor is running, which for coolant is understandable.

I now have 2 jugs of 50/50 anti-freeze in the back seat to keep it topped off as needed for now. What's the easiest way to tell if it's the water pump or the gaskets that are leaking? I really hope it's the pump!