'01 w/ 5.9 R/T- I had running hot issue for a while. I'd changed everything out except the water pump. (flow wasn't an issue as it was just running hot, not overheating) New eletric fan, radiator, hoses cap thermostat and so on. I started noticing a couple of drips that seemed to come from the front drivers side of the engine bay by the headlight. Not very often, just a few times a month. Well the other night my wife calls and says the temp was way up and she had pulled over. She was only a mile from the house so I told her to give it a while and try to make it to the house so I could look at. Well she got a quarter of the way from there and it got hot again. I told her stay there and I would come look at it in the parking lot of where she stopped. Long story longer, it was low on coolant, I refilled it and we went home with no other issues. I also noticed that the coolant overflow bottle was still full. ??? The next day, I looked under the cap and it was low on coolant AGAIN! On a hunch I took the resevoir/fan shroud/wiper fluid bottle off the truck. I left the tube that connects the over flow to the radiator cap attached and tried to blow thru it. No luck! It was clogged! I cleaned out what I can only describe as "black muck" out of the hose with a coat hanger and then with the water hose to get the rest. The over flow bottle was also pretty full of the stuff too. I spent a good 30-45 minutes getting it all out and putting it all back together. After that I refilled and burped the system. We'll see if it's low on coolant again later tonight.

I think that with the hose being clogged it was sucking air bubbles into the coolant system and causing it to run hot. This was the first time I had thought to clean out that part of the cooling system and I just wanted to pass along my experience with it. If you have to cooling systen drained for whatever reason, go ahead and check that part out as well.

 

You are correct.


This is a classic problem that is unwritten (accept by me)! What happened is the cap couldn't release the pressure so one it got over the pressure rating is blew the safety spilling the hot coolant (steam) out into the air. Once it cooled there was not H02 to supplement, it sucked in air. Over and over this happens finally causing it to run low.

You need to replace your radiator cap and T-stat now as they will be week from overheat.

 

Hmmm...... You're probably right. Damn! I was hoping to be done with coolant issues. Oh well, ounce of prevention, right. Hey anyone know an easy way to get the coolant out of the upper hose? The way it's designed, coolant pours all over the place when you remove the hose from the T-stat housing. Turkey baster maybe??

 

You can get a hand-held siphon from the parts store or use a three foot length rubber hose and get to suckin'!

 

Update- After cleaning overflow tube and resevoir, the truck ran cold! We had a couple days of 30 degree mornings here in Texas and the check engine light came on when my wife was on her way to work. I had her stop by an auto parts store and they read the code. Ended up being the thermostat as Hydra stated. I'm betting that it was stuck open for a while before I cleaned the tube and resevoir and that's the only reason it never overheated. Changed the thermostat and gasket, refilled and purged system. Wife said it ran perfect this morning even sitting in traffic. Thanks for all the help and suggestions. Now I'm off to search the threads for a couple more issues I have with the truck.

 

glad we were able to help ya out man

 

Sounds great!.....Glad we could help.