Head Gasket question?

[jkern]

For about the last year, when I shut off the truck I hear a gurgling/bubbling sound coming from the firewall area. I can hear it clearly in the cab as well as under the hood. I have not pinpointed the exact location. I have also noted that the radiator is always low on coolant...like 2-3 quarts, but the coolant reservoir is always full and seems to get fuller over time. The coolant is the proper orange color, but opaque and "slightly dirty" looking, more concerning though is the feel of the coolant is very slippery (oily) in nature. The oil seems fine. I run a HS Minimax, but honestly I run in stock mode 90% of the time and only in tow or street mode very rarely when I am towing. Truck has 147k miles on it. Does this sound like a tiny head gasket leak or what other issues could cause this? Truck runs fine otherwise.


2011 2500HD Megacab 68RFE

 

[Ozymandias]

Try a new radiator cap, you probably loose it there.
The always full coolant bottle tells me that.
Easy and cheap stuff first.

HG would be also easy to diagnose with the engine running and a CO Tester. There are also test stripes available for DIY mechanics.

 

[jkern]

I replaced the radiator cap as suggested, no change at all. I also got a hydrocarbon test kit and did the test per the instructions twice. Attached is the color change, blue is the original fluid color and the green/yellow is the tested fluid. I understand that diesels may not have the same color change results as gasoline engines. I am also awaiting a oil sample analysis from blackstone.

 

[petersonj]

I have also noted that the radiator is always low on coolant...like 2-3 quarts, but the coolant reservoir is always full and seems to get fuller over time

What you mention here is a symptom of combustion gases leaking into the cooling system and forcing coolant into the reservoir. The coolant doesn't return to the radiator as it should when the engine cools after shutdown because the combustion gases inside the radiator contract, instead. Once the radiator seeks its own level, excess coolant will no longer be forced into the reservoir. However, if you top off the radiator, then the cycle will start all over again.

Try this. Don't add any coolant to the radiator. Make sure the reservoir is at least have full. Run the engine. Watch for a continuous flow of air bubble surfacing in the reservoir. Be patient and look for the bubbles under different operating conditions or engine temperature conditions.

If you do see a continuous stream of bubbles, that is a sure sign of a head gasket leaking.

- John

 

[sag2]

The head gaskets usually don't fail, more likely would be the EGR cooler.

 

[AH64ID]

Is the truck tuned or stock?

 

[NIsaacs]

Is the truck tuned or stock?

From the op.

"I run a HS Minimax",

 

[AH64ID]

From the op.

"I run a HS Minimax",

Whoops.


Tuned trucks are more prone to HG issues, especially the early 6.7’s.

 

[jkern]

Little late in my reply, Yes I have a Minimax, but run the stock setting almost always, rarely bump it up, no EGR on the truck. Rest of the engine/transmission is totally stock. Noticed today that the coolant in the overflow tank is way overfull, radiator is really low and the oil is a little over full. I sent a sample to Blackstone this week, I am preparing for the worst. Been doing a lot of reading...I have no specific reference or exact details that I can cite, but I understand the 6.7 block is generally the same as the 5.9 block with different bore specs...this makes sense then why the 6.7's have occasional failures...more combustion pressures, less "meat" between the cylinder bores which is reportedly where the head gaskets usually fail.

 

[SRay]

I have just recently experienced bubbling coolant in my 2005 freightliner with a C15 cat.

A little worse than your truck as I smelled the coolant as it’s being released by the rad cap.

After releasing the pressure with a rag, I peered into the cooling system and seen bubbles coming up.

Called the boss, said head gasket failed.

The Cummins 6.7’s are known for head gasket failures as the truck gets older. More so with power adders. Even using that power only for 10% of the time will still be enough to cause a gasket failure.

Be the same as a 12v cummins for example, as the truck gets older, the head bolts get a little looser from years of heat cycling. Then put in more boost from extra fuel, the head gasket pops.

I had my 1997 12v head bolts re-torqued before going over 40 psi of boost. Some of the bolts were looser than others which would’ve been a head gasket failure for me too. But so far I haven’t had any yet.

 

[Ozymandias]

More likely the EGR cooler. Check that first before you rip apart the engine.

 

[jkern]

Update: The head gasket failed in grand fashion yesterday. Noticed the truck getting hot while on the interstate, overheated quickly. pulled over let it cool off, only to find the overflow bottle completely full of murky white orange coolant and the radiator empty. Fortunately, I came up with a rescue plan...filled it up with water, drove it until it started to show signs of getting hot again, stopped refilled with water, etc. took 7 gallons to get me about 20 miles to home.