Burping the cooling system?

[GrantP]

I've owned my '06 for nearly three years now and I have no idea whether the previous owner ever changed the coolant (I doubt it). I've read about the nightmares about removing the draincock and not being able to thread it back in, fortunately for me I just loosened mine a half turn and the coolant drained nicely into a 5 gallon bucket. I figured I was on the downhill stretch now, I dodged the problem with the draincock. Well after ~30 minutes I had drained about 4 gallons of coolant and I shut the draincock and went to refill. The problem is I could only get 1.5 gallons in the radiator. Figuring I needed to get the truck warm to open up the thermostat I did a short drive around the block, the temp gauge showed a hair over 200 and I pulled it back in my garage. The radiator cap and upper hose were still cold so I let it idle some more and the temp stayed just slightly above 200. I shut it off and carefully opened the radiator cap to see that the radiator is still full! I took it around the block again but this time the temp gauge got hot, 220-230 on the gauge which scared the crap out of me. I opened up the radiator cap again and apparently the thermostat had finally decided to open and I put another 3 gallons in. Once I dumped in the new coolant I restarted the engine to cool it down and all is well.

My theory is that there was no coolant actually touching the thermostat and that is why it took a near overheat situation to get it to open. For future reference, what's the best way to get the air out of the system when doing a coolant change? I've read a reference in the manual to some "jiggle pins" that are supposed to allow air out but that didn't seem to work at all. I think I'll be removing/replacing the thermostat when I do this next time but maybe there's a better way?

 

[BILTIT]

Pull the heater core hose off the nipple on the top of the head passenger side (sticking straight up). With it off, fill until coolant comes out the nipple and put hose back on. A good run to warm up and open tstat then re-check level once its cooled. Be sure you drain and put new coolant in the overflow bottle also.

Works like a dream!

 

[GrantP]

Thank you BILTIT! I will try that next time.

 

[Ozymandias]

I suppose you have an aftermarket thermostat in your truck - without the airhole in it.
I drained my truck also completely and I filled it in one single shot completely without any hassle.
Filled the radiator, filled the overflow bottle and been done.

There is something wrong with your truck with that problem.

 

[Ozymandias]

Postscriptum; I always fill the overflow bottle up to the topcap (far over Max.) and let the Engine level it by itself.

 

[GrantP]

I'm 99% sure it still has the OEM thermostat, the truck only had 21k on it when I bought it.

 

[AH64ID]

Either the thermostat is not OEM or it was filled too fast.

The OEM thermostat has 2 jiggle pins that are designed to be self burping, as you read, but if the radiator/block are filled too fast they won't work as intended.

Here is a writeup on the coolant change. Based on the design of the cooling system it's pretty important you don't use pre-mix coolant and you only stick to HOAT G-05.

https://www.turbodieselregister.com/threads/218402-Coolant-flush-on-a-3rd-Gen/page3

 

[GrantP]

Thanks John - I read your post before I started the coolant change. I did use straight Zerex G05 and added some distilled water. I may be guilty of filling the radiator too fast, but I only got 1.5 gallons in and I couldn't fill anymore. I'm not sure why the speed of refilling would matter? FWIW, I did tap the thermostat housing with a rubber mallet a few times hoping to "jiggle" the pin with no luck. In hindsight I wish I had just replaced the thermostat while I was at it.

 

[Grey Wolf]

GrantP

I like to open this pipe plug on the head to let the air out. Works every time for me

 

[GrantP]

Thanks Grey Wolf. Given the suggestions I'm clearly not the only one to have had this problem. Now I have a couple of good solutions for the next drain, thanks guys.

 

[DaveHess]

The only thing I did different was make a "Hawaiin Stat" (gut an old thermostat so the center is open). When I got to part of refilling with new coolant, I put in a new T-Stat from Cummins. Worked good.