OK. It stopped working. Just cold air. I flushed and reverse flushed the heater core. I also flushed the rad and all the rest of it. Replaced the coolant. Heater worked great.... for about a week. Flushed the heater core again. Heater worked great... for only 4 days this time. Do I really need to flush it agan or is it time to replace the heater core?

 

Really? no one?

 

The heater core may not be the problem, Check the thermostat and water pump.

 

I swear I replied to this a few days ago, but then again I have been having trouble with access to the site lately...

Anyway, what I remember typing up...

How was the flow through the heater core when you flushed it? Did the water come out pretty strong? Did it feel like there was a backup in the system? How has the truck been warming up in the morning? Did you make sure to get all of the air out of the system when you flushed it? How did the coolant look that was coming out of the heater core and/or engine block while you were flushing it out?

 

I changed the thermostat before I did the first flush. It flushed out yellow brown the first time. Second time was pretty clean. A littleslow at first but very strong with in seconds.
How do you test the water pump? I though if a water pump fails, it leaks.

Truck warms up fine. Quickly as it always does. Gauge is normal. Stays normal in trafic or cursing down the hwy.

 

If you didn't get all of the air out of the system, it tends to collect in the heater core. I will typically lift the front of the vehicle as high into the air as I can to make sure that the radiator is the highest point in the system to attempt to remove any air pockets. But a few days of driving around should also clear the air pockets out... Hmm...

 

Have you rechecked the coolant level when the engine has cooled to make sure that it's still topped up? The coolant level will normally drop after the thermostat opens.

To check if the water pump is working you would have to have the radiator cap off and with the engine running and warmed up you should be able to see the coolant flowing in the rad.

I've also had trouble getting on to the site for a few days.......technology!!!!