LBZ running hot

[TNTupinsmoke]

I have a 2006 LBZ 4x4 running at 275 when I put a flat bed trailer on also the ac is not cold when driving in town. I have 100k miles on it. I just bought the truck where do I start to figure out the problems. My friend has one and it runs great and has ice cold air.

[DmaxMaverick]

I'd start by looking at the fan clutch, and verify the cooling stack isn't obstructed (leaves, bugs, dirt, plastic bag, etc.).

[Mark Rinker]

Hey - welcome aboard, and don't forget to fill out your profile and signature with truck information...

Ditto on the cooling stack, plus make sure that the coolant level is actually correct. Sometimes the plastic overflow bottle can become stained from the inside out, and appear full under a quick visual inspection when in fact, its not. At 100K, a flush and refill of coolant would be advisable, especially if you tear into cleaning your cooling stack and have the radiator out of the truck, anyway...

I have run two '06 LBZs, and the second that I have owned is more prone to running hot than any other Duramax owned to date. Will be posting some observations from my latest trip from FL back to MN, towing a 15K boat/trailer combo in 1200 miles of mid-90F heat. I have been watching a very predictable and repeatable cycle that reinforces what has been discussed here on TDP, and may be pursuing some hard-part remedies for it.

Question for DMax...will an '01-'04 LB7 fan clutch bolt up to an '06' LBZ fan? MP suggested this idea some time ago, and I am ready to replace mine if possible - as it comes in WAY too late.

Qs: Are you running any kind of performance tune? What are the ambient (outside) temps when you are running hot? What is your GCVW? Ground speed and terrain?

If you are running even a 'tow-safe' tune, get the truck back to stock and see what your results are for comparison. Running additional fuel rates while towing in the mountains, or in hot ambient conditions on the LLY/LBZ can result in a turbocharger initiated heat soak cycle.

Also, read this thread carefully and in its entirety. It was started long ago...but may apply to what you are seeing ...

http://www.thedieselpageforums.com/tdpforum/showthread.php?t=7900&highlight=LB7+fan+clutch

[Kennedy]

The LB7 clutch might bolt up, but keep in mind you'll want a used one as the new ones LLY/LB7 are said to carry same part number meaning the LLY part supercedes the LB7 unit.

This is much like the 6.5 fan clutch B.S. Consumer complaints of noise and reduced economy and power moved GM to calibrate to a higher engage temp. This means the weekend warriors are happy, but the guys that work them hard have troubles.

[TNTupinsmoke]

where to look for the cooling stack to see if it isn't obstructed? Also any problems with the AC not running cold? How can I check to see if it has a program installed from someone else. This is my fathers truck he lives in kansas where land is as flat as a board. I talked him into buying it after i bought my o6 and runs great and has cold ac.

[leolkfrm]

I found my a/c was not doing well at idle, put the guages on it and found no problem. Put some thought to it and realized I had not been hearing my clutch fan like last summer.
Took the air hose to the front end and had a dust storm! then hosed everthing the best i could from the engine side, it left a dirt spot in the driveway. but in the end i now hear the low speed fan and my a/c has returned at idle
Just some thoughts!