2011 solutions to LLY overheating popblems

[gcburt]

Is there anyone currently working with the overheating problem on LLY engines

[More Power]

The following link contains more detailed instructions that outline the best solution for the 2004/5 LLY (i.e. 2006/2007 LBZ radiator, fan, fan shroud and other stuff).

http://www.thedieselpageforums.com/tdpforum/showthread.php?t=39208

Jim

[CoyleJR]

My 2006 LBZ has the same heat issues that Mark Rinker had described with his old 2006 LBZ. The engine coolant heats the ATF which does not cool off for a long period of time even after the clutch fan has engaged and cooled the engine. Mark had indicated that his new 2009 LMM does not have the high temperature issues that his old LBZ had. Does anyone know what GM changed to fix the high temp problem on the 2009 LMM and can it be applied/adapted to my LBZ.
Thanks
John

[gcburt]

My 2006 LBZ has the same heat issues that Mark Rinker had described with his old 2006 LBZ. The engine coolant heats the ATF which does not cool off for a long period of time even after the clutch fan has engaged and cooled the engine. Mark had indicated that his new 2009 LMM does not have the high temperature issues that his old LBZ had. Does anyone know what GM changed to fix the high temp problem on the 2009 LMM and can it be applied/adapted to my LBZ.
Thanks
John

John

On another forum I see that folks are fixing their transmission heat problems with a replacement oil cooler - I'm not sure of the ultimate source, but Mike L. (at Inglewood Transmission Service - (714) 870-7300) can drop-ship one to you

Not sure if that may help your situation or not.

Garth

[More Power]

My 2006 LBZ has the same heat issues that Mark Rinker had described with his old 2006 LBZ. The engine coolant heats the ATF which does not cool off for a long period of time even after the clutch fan has engaged and cooled the engine. Mark had indicated that his new 2009 LMM does not have the high temperature issues that his old LBZ had. Does anyone know what GM changed to fix the high temp problem on the 2009 LMM and can it be applied/adapted to my LBZ.
Thanks
John

What sort of operational situation(s) does your LBZ/Allison overtemp? What is the condition of the cooler stack (bug/leaf buildup)?

Jim

[CoyleJR]

Jim,
You asked what operational situations cause the high temp issue. The problem occurs when towing with a GCWR of 22k to 24k in mountains and the ambient temp is above 75F. As you start up a substantial grade, you can watch the engine coolant temperature go from 185 to 215. The ATF will lag behind the coolant temp rise for a short while. The ATF temp that had been 170 will then start to rise quickly to equal the 215 as it absorbs heat from the shared coolant in the radiator. When the clutch fan engages, the coolant temp drops very quickly, but the ATS stays hot for many more miles. In my opinion, after the ATF has passed through the radiator and absorbed heat from the engine coolant, the small trans cooler at the front of the cooling stack can not handle the heat load.
I hesitate to install a larger trans cooler at the front of the cooling stack because it will just dump more heat into the AC, intercooler and radiator.
I take the cooling stack apart about once per year and clean it. I also regularly pressure wash the fuel cooler. Additionally, I never tow with any power programmer on due to the high EGT. The truck is completely a stock truck, other than a Mag Hytec transmission pan.
When Mark Rinker had his 06 LBZ he described the exact high ATF temperature issue and it never caused a problem. It just makes you uncomfortable on a hot day in hill county.
Mark has indicated that his 09 LMM does not have the high ATF temp issue. What did GM change????
John

[dunny96]

When towing that much weight, I would consider 210-215 on engine temp and 200-210 on tranny temp "normal". I would not even consider it "above normal". My lbz runs the same temps towing 10,000lbs in the summer heat on flat land. The tranny temps are slower to drop than the engine temp, after the fan kicks off, due to the volume of fluid moving through each. The tranny temps would have to get a lot hotter than 220 before I would start worrying.

[gcburt]

When towing that much weight, I would consider 210-215 on engine temp and 200-210 on tranny temp "normal". I would not even consider it "above normal". My lbz runs the same temps towing 10,000lbs in the summer heat on flat land. The tranny temps are slower to drop than the engine temp, after the fan kicks off, due to the volume of fluid moving through each. The tranny temps would have to get a lot hotter than 220 before I would start worrying.

Query for everyone in the Group: Just at what temps should one start to be concerned (ease off)? AND when to I need to pull over and let things cool down at idle (fast idle)??

[CoyleJR]

I should have been more specific about the temperature. The highest the trans and motor have ever been was 235 degrees. That is much hotter than I am comfortable with. The 235 was on a six mile long six% grade on a 110 degree day. It is not uncommon to hit 220 or 225 degrees climbing a hill on a 80 degree day. The engine gets hot first then the trans heats up to the same temp as the motor. It is clearly pulling heat from the engine coolant and dumping it into the ATF (because they heat up to the exact same temp). When the clutch fan engages it drops the coolant temp quickly but the ATF stays hot for many miles.
The truck has 175k miles on it with all appropriate maintenance with no serious trouble. I am hauling at the max capacity of the truck and the high temperatures have not hurt anything. The truck apparently is designed to handle the heat for short periods of time. I just get worried when it gets over 220 degrees.

All else aside my primary question is if Mark Rinker's 09 LMM does not have the heat issues that he had with his 06 LBZ, what did GM change?????
John