nlogsdon

Ok, so I have a 2000 Chevy K3500 dually with a 7.4 gas Vortec. I have been battling an issue with no heat for some time now. I can do simple things, like changing oil, alternators, basic tune-ups, brakes, etc, but for bigger projects I go to a local shop and pay them to do the work. Recently I've fallen down a rabbit-hole, or rather my wallet has, and I think I'm getting screwed. I'm hoping someone can help me out.

Truck started running hot one day, but didn't actually overheat, (I pay close attention to my gauges) so I figured it was probably a thermostat problem. I didn't have time to do it, so I took it in to the shop. (Yeah, I know. Shame on me...) They replaced the thermostat and everything was fine. A few weeks later, I discovered I had no heat. Tried another thermostat. No change. The shop has continually suggested new things to replace and to make a long story short, I now have a new:
Thermostat
Radiator
Heater Core
Water Pump
Upper and Lower Hoses (Radiator and heater core)
Blend Door Actuator
Temperature Gauge Sensor
plus it's been flushed three times now.

I've spent thousands of dollars trying to fix this and I still have no heat. The shop now says that the new radiator is clogged and they want me to pay for another one. I said no... I'm going to try a different shop, but I want to know what I'm up against here.

The current symptoms are as follows:
1) All controls work properly, but no heat. The cool air that comes out of the vents is not as cold as the outside temperature, but nothing that could be described as "warm" in any way.
2) The top half of the radiator is hot to the touch. The bottom half is cold. (I will get actual temperature readings hopefully tomorrow)
3) One heater core hose is warm, not what I would call "hot", the other is warm-ish.
4) The temperature gauge is reading a consistent 190-210 degrees once it warms up, which takes about 10 minutes.


Can anyone give me any suggestions? Is there anything I haven't replaced yet? I swear, I'm waiting for this mechanic to tell me I need a flux capacitor!

Thanks in advance!!

burnhedge

I think my first move would be to get the engine up to temp and pull the return hose on the heater core to verify your getting flow through it.
If 190* coolant is flowing then it must be the blend door. I haven't had to fool with a chevy blend door but I know some Fords had a big problem with the shaft on the door breaking. The actuator can be functioning properly but door doesn't move.

THORX4

So heater core replaced? Is yours OBS? my 99 is. Sounds like a blend door either stuck or a air hose is loose the vacuum lines.

cleveland63b

does the air coming from the heater get hot if you hold the rpms up? feel or get a vent reading at idle (operating temp of course) then hold it to 2500rpm and see if it gets hot


from what you've described it sounds like a blend door/temp door problem or maybe just air in the system

nlogsdon

Ok, it's not the blend door. I was able to burp some air from the system and get a very tiny, lukewarm improvement in the heat. I took it in to the shop to have them burp it because I figured they could do a better job there than I can on a hill in my back yard. They claimed to have added more antifreeze and immediately got 180 degrees out of the vents and told me to come pick it up. When I did, there was NO heat at all. I put it back on the hill and burped it again, got a little more air out and topped it off, resulting in lukewarm temps again. (Nothing even CLOSE to what the shop claimed they got.) I drove it around the block and tried to burp it again, but got nothing. Still at lukewarm. Temp gauge reading 210. I drove it up into the driveway, back on level ground and it started blowing ice cold again. Anyone have any suggestions? It's starting to look like it's air in the lines, but I can't get it out!

nlogsdon

I've discovered that it does get slightly warmer at 2500 rpms. Also, after holding 2500 rpms for a bit, after letting off, it gurgles fluid out a few seconds later. (Radiator cap is off) Is this normal?

nlogsdon

After getting out as many bubbles as possible, the heat was blowing pretty good. However, once on level ground again, it went back to blowing cold. Could there be more air in there? What are the chances that they installed the heater core hoses backwards? Would it hurt anything to try reversing them?