Duramax Coolant issue

Corey Owner/Technician Kenton, Ohio Posted   Latest   Edited  
Resolved
Drivetrain
HVAC
2006 Chevrolet Silverado 3500 LS 6.6L (2 LLY) 6-spd (1000) — 1GCHK33286F121411
No Heat And No Coolant Flow At Idle

I have this 2006 Duramax that I have no heat at idle in the cab and the engine temp gauge drops to cold after you run it down the road and had it at operating temp. I've installed a clear hose in place of the heater hose to check for flow and idling there is no flow at all. the tube fills up with air. I have a Tee with a valve on it to bleed out air and I can bleed all the air out of the hose so it is full of coolant but there is no movement of the coolant and soon the hose fills up with air again. I have a pressure tester in place of the Rad cap and the system was running around 12 psi. I've bleed the air out a dozen times to have the hose completely full of coolant but it doesn't take long and the coolant is gone. When you speed the engine up to 3000 RPM it take a little but soon you see a the coolant gushing through the hose but it looks like it is well mixed with air bubbles and while revving the engine the temp gauge comes back up, let off to go to idle and eventually the temp is down close to the cold mark and heater hose is all full of air.

This truck has been losing coolant and spewing coolant out for the customer but has always run fine but he keeps coming back with this low coolant and spewing out problem. I've checked over the system and can't find any leaks but I'm wonder if the water pump is bad. But were is all this air coming from?

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Zachary Mobile Technician
Austin, Texas
Zachary Default
 

Good afternoon Corey, Sounds like you've done a fair bit but I do have some questions. How are you going about bleeding the air? There's an air bleed on top of the thermostat housing but I find the best way to fill these is with an airlift tool. Does the pressure ever spike on the gauge when you have the tester hooked up to the expansion tank? I assume the coolant is spewing out of the…

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Corey Owner/Technician
Kenton, Ohio
Corey Default
 

Yes I have bleed it out at the thermostat housing and not sure if I've mentioned it I even replaced both thermostats also. I also pressurized the system some and opened my valve in my clear hose to bleed the air out there and then let all the pressure out before starting the engine. I never saw a spike in the pressure gauge and yes it would spew out the expansion tank for the customer. No I…

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Zachary Mobile Technician
Austin, Texas
Zachary Default
 

I agree about the block tester. There is a different fluid for diesels but even still. It's one of those things that if it says it's bad it's bad but if it says it's good it could still be bad. Kind of like an ohmmeter. Your best bet would be a five gas analyzer if you have one or can borrow one. Checking the impeller on the water pump would be labor-intensive as those are gear driven and a long…

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Corey Owner/Technician
Kenton, Ohio
Corey Default
 

I decided to see if I can scare up a gas analyzer around this town to use before I dig into the water pump and thanks for the info on that. I figured it wasn't going to be easy from what I was seeing and I haven't done a lot of work on these engines other than fuel injectors and EGR so I'm not so knowledgeable on these engines. I have a handful of customers with these engines so I don't see them…

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Zachary Mobile Technician
Austin, Texas
Zachary Default
 

No problem at all sir. I think the gas analyzer is a good plan. The water pump is a good job when you have to replace one, but the first one will kick your butt. Or at least the first one I did kicked mine. Like a former coworker used to say, experience is what happens when you don't get what you want. On a separate note, I like that the truck you're looking at is a 6-speed manual. Hard to find…

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Corey Owner/Technician
Kenton, Ohio
Corey Default
 

Sorry Zachary, This is an automatic. Thanks for bringing that to my attention and sorry for your let down. I clicked on the wrong transmission option. My mistake - I put the VIN in and choose the 6spd and didn't see what one I clicked until you mentioned it.

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Albin Diagnostician
Leavenworth, Washington
Albin Default
 

that sure sounds like this engine has head gaskets leaking, but like Zach has mentioned, do some testing to see if there is exhaust gasses in the coolant.

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Douglas Technician
Hermon, Maine
Douglas Default
 

Common head gasket symptom. I agree with testing for exhaust gasses in coolant. If it is gaskets I recommend installing the ARP head stud kit to fix it for good. Good luck

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Ryan Owner/Technician
Prince George, British Columbia
Ryan Default
   

As others have stated, it definitely sounds like a head gasket issue. Head gasket failures can act very different on a diesel vs a gasoline engine. Just revving the engine in the bay does not create cylinder pressures you would see at full load and boost. Does this have any performance modification? I generally test the cap opening pressure and then test drive while monitoring cooling system…

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Daniel Owner/Technician
Bedford, Quebec
Daniel Default
 

Hi ,remove the glow plugs and pressurize each cylinder .Sean many delaminated head gaskets on duramax , take your time , leave the pressure for a while ,shop air has lower pressure but will find is way !Just like Douglas said, love ARP on them ,Dan.

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Martin Instructor
Burnaby, British Columbia
Martin Default
 

Hi Corey. A lack of heat and a pressurized cooling system with the symptoms you describe "scream" head gasket failure. As others have alluded, compression test fluid doesn't work well with diesels, at least the most commonly available chemicals. Years ago on other GM diesels before the Duramax (which has a gear-driven water pump), a quick way to determine which cylinder bank the air was coming…

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Richard Technician
Stony Brook, New York
Richard Default
 

Those symptoms sound exactly like a head gasket issue. If you used an airlift tool to vacuum the air out and then it is still getting air into the system, it must be coming from inside the engine. I would feel confident in selling that repair. But I probably wouldn't do it, I would send it to someone else. I'm not much of a diesel guy. :)

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Thomas Owner/Technician
Constableville, New York
Thomas Default
 

I have not personally done this test yet, but I am going to try with my next suspected diesel head gasket failure. If you have a scope and a pulse sensor you could make something to hook to your pulse sensor to your pressure tester adapter on the radiator and sync using one of the fuel injectors, look for a repeating pattern/anomalie on the pulse sensor trace. It may be worth giving it a shot…

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Albin Diagnostician
Leavenworth, Washington
Albin Default
 

I have tried that on several vehicles, and have never gotten any results that were conclusive. Before you try something like that on a broken vehicle, try it on a few known good so you know what good is.

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Thomas Owner/Technician
Constableville, New York
Thomas Default
 

Alibin, I agree completely.

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Zachary Mobile Technician
Austin, Texas
Zachary Default
   

That's interesting Thomas I hadn't thought to try that yet. Definitely agree that some known goods are needed as a baseline, but it would be pretty cool if that could be developed into a viable testing method.

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Corey Owner/Technician
Kenton, Ohio
Corey Update
 

Hello every one. Thanks for your input. I tired using the block testing fluid but it was so so saying it was bad but by leaving the coolant cap off I would get flow through my heater hose and it was bubble after bubble coming through. A sure sign of head-gasket issue. and when I would rev the engine it would be coolant shooting out of the coolant tank. By all means he has a head-gasket issue. I…

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Ryan Owner/Technician
Prince George, British Columbia
Ryan Default
 

"This truck does have a tuner on it and they were making use of its power frequently." BINGO!

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Albin Diagnostician
Leavenworth, Washington
Albin Default
 

Knowing the engine was running a tuner is enough to go straight for head gaskets.

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Martin Instructor
Burnaby, British Columbia
Martin Default
 

Hi Albin. The word "tuner" alone is cause for an immediate "divorce" for me, from the pile of junk that has resulted inside an otherwise previously sound engine. We had many of these wonders and their know it all owners arrive at the dealership with melted pistons, damaged bores and rod damage from severe over fueling, all seeking warranty of course! Merry Christmas to you, Alice and the kids!

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Corey Owner/Technician
Kenton, Ohio
Corey Update
 

The reason I did not condemn it right away even though I was for sure certain it was head gasket issue is because this thing was in the shop a year ago and was starting to show such signs slightly and I told him he is probably having a head gasket issue. "truck is running fine" so I dropped the subject. He has had it to another "mechanic" shop. (I call them a back woods shade tree DIY mechanic)…

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Corey Owner/Technician
Kenton, Ohio
Corey Resolution
 

Waiting till customer has money and we can do the job.

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