Anybody familiar with a "mouthpiece?"

[John Wood]

Have a 2004.5 K2500 HD DA. When pulling a 10,000lb toy hauler here in New Mexico (elevation 7000 ft ASL) up 6% grades tranny & coolant tend to overheat. A friend says that a mouthpiece for the 2004.5 LLY is the answer? Evidently it's a slight mod to the turbo intake system that dramatically reduces overheating. I would've thought an external tranny cooler and/or increased radiator/cooling fan, etc., but he says this mouthpiece is the most simple technique for mitigating cooling issues for the 2004.5 LLY. Is this the straight skinny or a bogus comment? I'd never heard of a "mouthpiece."

[rapidoxidationman]

There's a lot of posts here on the LLY overheating issue and the solutions available. IIRC lots of folks take some parts from a 2006 (LBZ?) to bump the cooling capacity of the LLY: bigger fan, bigger clutch, bigger radiator, bigger radiator shroud.

Other folks just ease off the go pedal a bit for the steep grades... That mod is free.

Edit: here's a thread to start your resolution:

http://www.thedieselpageforums.com/tdpforum/showthread.php?t=27036&highlight=LLY+overheat

[DmaxMaverick]

The "mouthpiece" simply refers to an upgrade to 2006+ air intake system. It will have a cool(er) air intake location, more unrestricted flow, and seems to work to reduce operating temps.

Of course, the other upgrades are as quickrustdude said. The previous models of the Duramax, apparently, generated some user complaints about noise and such, so they quieted it down, and reduced the cooling capacity at the same time. A "less noisy" fan is a less effective fan. Simple as that. I don't think upgrading the radiator and fan/shroud is necessary for everyone, but the clutch, thermostats and intake system goe a long way for most users. In the extreme, all/any of the above may be necessary.

[Kennedy]

The "mouthpiece" is a lot of hype in my opinion. The OE piece has plenty of area through which to flow air.

If it really was necessary or made a difference there would be a good scientific test outlining dyno performance gains.

It won't hurt to do it, but it also won't help.

[06SILVERADO]

Google "duramax cooling stack" and like rapidoxidationman said let off the pedal and watch your EGT"s

[More Power]

The reality is that not that many LLYs experience overheating. It's just that we hear of those that do.

Your 2004.5 is now old enough that it would be time to remove the grille and thoroughly clean the cooler stack (ATF cooler, A/C condenser, intercooler, and radiator). Bugs and other debris have a way of accumulating to a point that the engine will overheat while towing heavy loads up grades in high ambient temperatures. Likely, this didn't happen to the same truck when it was newer and the cooler stack was cleaner.

Jim