I just fixed my heater problem this weekend.
History: 1998 Dakota, 155000 miles. About two years ago I had very luke warm air coming into the cab no matter what the temp guage read. I replaced the stat and checked to see if I had flow thru the core. I did have flow, but still no heat.
This weekend: First flushed system with Prestone flush. That did not help. At all times, the coolant appeared clear and bright. Next - bought a Prestone Back flush kit and followed the directions. That didn't help.
I then replaced the thermostat. Still no change.
Then I removed the heater hose at the water pump(hose 1), disconnected the heater hose from the top of the engine to the fire wall (hose 2) at the splice, shoved in a water hose nozzle and sprayed.
Nothing came out but clear water. I then put the hose nozzle in the end of hose 1 and repeated, out came a bunch of grey sludge and water. I thought I was finally getting somewhere.
I kept going back and forth from hose 1 to hose 2 until no more cloudy water came out of the heater core, put it back together, tested it and still no change.
I was about to give up when I went back to the splice on hose 2, disconnected it, put the hose nozzle in the end going toward the top of the engine, removed the radiator cap and let it rip.
I put it back together, filled the system and worked all the air out and HOLY COW I have heat. 125 degrees coming out of the defrost.
I mentioned everything I did because I'm not sure if it was one thing or a combination of all events, but I think it was clogged at theheater hose at the top of the engine where it joins near the stat housing.
Hope this helps.
Monday, November 12th, 2007 AT 7:39 AM