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Coolant disappearing, Head gasket diagnostics?

Ed HD

Ed HD

Formerly: Dad's 05 LLY
Messages
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Location
Chuck Town, Iowa
Mom has been driving the Duramax lately, the other day she got in to a Low Coolant message, they checked it and added about a quart. What's the best way to test for a leaking HG? Pressure test? Could the WP be leaking? They're telling me that it's not leaving anything on the floor in the shop , but with it being winter it could easily be getting lost in the snow dripping. I need to get in and replace the P/S pump (see other thread, wanted to keep these separate) and I know you gotta pull the HB, but it'd be easier to do it all at once.
 
The best way I have found to check the water pump is to look for the orange all over under the weep hole and the oil pan behind it. Its not uncommon for water pumps to leak sporadically. Leak alot, then stop, then leak again. Head gaskets normally leave you with a pressurized cooling system after it sits overnight.
 
Yeah, most parts stores have it. Might take quite a bit of it though.

Sent from my SAMSUNG-SM-G890A using Tapatalk
 
Napa carries the dye, problem is dexcool is so slick itvtends to just run right off. It does tend to leave orange traces behind if it leaks when hot. Also you need to check the turbo cooling hoses. Theres one back behind the fan idler that is known to leak, and is a pain to change out.
 
http://www.dieselplace.com/forum/76...ramax-coolant-leak.html#/topics/737618?page=1

My dad found that post in a google search and is convinced that it's the culprit. Could air in the system really be pushing coolant out? It doesn't leak while sitting, but it did hold pressure when a shop tested it. Wouldn't air naturally bleed at some point and the coolant loss stop?

@THEFERMANATOR , I know you said they can be a pain to bleed, but I've never seen air push coolant out of a system?
 
I havent encountered air pushing coolant out either. I like to fill the bottle all the way up, open the bleeder at the housing until it's purged, then slowly take the outlet heat line loose at the engine side to purge it there, then I take the small line at the top of the radiator loose until it's purged there. Drive it for a day, then it will normally take another 1/2 gallon or so. The whole point of a degas system is air will eventually purge out of the system. I've seen others do this stuff, think it's fixxed, then have it return regardless.
 
Mityvac mv4500 or airlift 550000
They pull the system down into a vacuum like doing an a/c system. While it is in vacuum, you verify there is no leaks. Then the coolant gets pulled into the system by the vacuum and fills it without airpockets.

Hummers have the problem with 6.5s worse than pickups, so I picked up the mity vac set up.
The dmax are having about the same issue, but most Americans aren't familiar with it. European cars a
Have been fighting this for decades. 1980's had a bunch of euro engines overheating because the mechanic didn't understand what was happening.

I hate doing the drive it a while till it burps thing. Those air pockets are uncooled metal suffering damage. 1/2 gallon low is kinda a lot.
 
The pocket normally isn't an issue as it is air entrapped in the top of the radiator. Knock on wood, I've never had an issue myself. Only heard of a handfull of people complain about it, and most of them end up having it come back.
 
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