Well, I will be honest... I am a little worried...

I really got sick of having no heat in the truck... so last night I took my truck into the shop after work to figure things out... I drove it around the block and inot the shop... was running maybe 5 mins...

I shut it off, got out, opened the hood, and the hoses had a good bit of pressure in them, thought that it was strange after running for so short, but let it be... Opened the rad cap to release the pressure and that was all good...

I had previously noticed that only the hose from the pass side of the engine was hot when running and that the one from the water pump was cold.. the heater core looked somewhat new, so I decided to flush it... ran some water through it and it seemed to flow nice... I hooked it back up and ran the truck to bleed the system...

Ran up nice, both hoses got nice and warm, and suddenly I had heat inside... was happy...

Now that I have driven the truck a few times I have noticed my heat is going away again....

Cooling system pressure and no heat.... If it wasnt for the fact it does not over heat ( unless towing at ultra low speeds ) I would be really worried about combustion chamber gasses in the cooling system... but even at this point its in my brain...

what do you guys think?? and if you think that it migh be, whats the best way to check... It does have almost 400 000kms ( 240 000 miles )

Thanks!
Bob

 

What is the state of the rad cap.......the hoses will have a decent pressure in them. I too am fighting wierd heating and have done all the test. The heater appears to have a mind of its own, when I let mine idle after driving around it will cook you. When I run highway speeds there is minimum heat sometimes.

There were problems with the blend doors staying open/jammed by pens etc falling into the system. But having hot and cold hoses may mean an airlock due to the fact the lines are higher than the engine.

I placed a Prestone flush T in my line to the waterpump and us it for air purging which has helped on occasion.....

 

in the past with vehicles not IDI, i have had to just let the motor run without the radiator cap to burp out the air bubble in the system. don't know if this will work with these systems or not.

 

It does work but i find if you rev the truck to 2000 rpm for 30 seconds it will really burp.