Duramax diesel coolant change - bleeding air

[stockrex]

I did a coolant drain and fill in my duramax.

I had to open the bleeder screw on top of the tstat housing and pour dexcool into the overflow tank,

The instructions say to pour dex till coolant starts to come out of the bleeder hole.

Well, I could not get any thing to come out of the bleeder hole even with the overflow tank all the full to the top.

1. I went ahead and burped the system but idling to temp with overflow tank cap open.

Q: Should I open and let air out of bleeder hole and check if I fluid to come out of it after the truck cools down?

 

[Astro14]

I would open the bleeder hole to be certain that you don't have a remaining air pocket.

The secondary (intercooler) cooling system on my S600 can't be bled via conventional means. It is separate, sealed, and has its own pump (electric) and pressure cap. The complexity of the piping means that you'll never get the air bubbles out by just filling it. There are too many high spots and places for pockets to form. Just the intercoolers themselves are at the high point in the system. A couple of huge pockets with schrader valves for bleeding...

Mercedes has a whole rig involving vacuum lines and other paraphernalia to properly fill the system.

I bought this: http://www.amazon.com/UView-550000-Airli...ailpage_o06_s00

It works great. It easily pulls 25+ inches of vacuum in the system, then you suck the coolant in through the adapter. No air bubbles.

To ensure that the intercooler system was properly done, I jumpered the pump to run, then repeated that vacuum fill process.

The tool isn't too expensive, and until I had to come up with a system for the intercooler system, I would never have even searched for one. But now that I have it?

OMG! What a great way to fill a cooling system! It takes just minutes, no air bubbles, no bleeding, no mess. It's just a great tool. My neighbor (who owns a NAPA autocare center in town) saw me using it, and said, "Yep, we have those, they're really great"

For your truck, you might seriously consider it.