ive been reading the posts on overheating and engine temps but my problem seems to be a combination of these. i tow a 8500lb 5er and the first time i pulled the trailer i took it to the sierras and went up the four lane (4 mi with grade up to 15) about 1/8 of the way up my clutch fan came on and i had NO power. I was red lined going 35 up the hill. clutch fan did not come off. took it to the shop they updated the computer and the next time it did the same thing. 3rd time to shop they changed water pump to lower gph and put in new fan. they also said they found piece of rubber in intake. took it up again and i had slightly more power but clutch fan engaged entire time and engine was at 235 deg. dealership said this was normal. it was only 40 deg outside and in the summer it gets 110 here so i know ill be calling gm's roadside assistance in june if this is "normal". Any ideas? This is the first diesel i have owned so i dont know normal. Please help me out because my dealership isnt getting anything done. My trailer is way too light and its to cold to be having these problems. Thank You

what type of tranny temps are you seeing when doing this? i must admit my Lb7 hasn't done that pulling my 8500lb boat & trailer up I80 at good speed. i presume your truck is stock?

My tranny temp fluctuates around 200. truck is 100% stock.

200 degree tranny temp while towing in not hot. 275 degrees is HOT. My LB7 tranny ran 150 to 180 normally and 200 when towing VERY heavy (33,000). My LLY tranny runs 140 to 180 normally, and haven't towed heavy with it - light towing 8,000 trailer tranny temp is 180 to 190. LLY in stock configuration so far at 4500 miles HAS NO POWER! Gutless wonder!

i wouldn't sweat the tranny temp. in the summer mine runs about 200 or a hair under unloaded... i know this topic has been thoroughy discussed in the LLY forum. you might want to do a search there. i'm moving this thread there as well

Its not the tranny i'm concerned with.does everyone else's fan clutch stay on for more then 10 minutes at a time? When that fan starts moving i have NO POWER! The mountain we go up is not that big and i watch other trucks with larger loads fly by me as im redlined going 35. This cant be normal can it. I read about guys getting buybacks because of faulty cooling systems in the lly. Any info on that? Ive always bought chevy and have never been disapointed i truly hope this is something they can fix because if its how its supposed to work then GM can have it back. Anyone know wher to get good service In Fresno,CA

My LLY clutch fan came on many time running up the Smokey mountains in TN, however my temp never got above 225 and it did not effect the power of the truck. Trnas temp at about 200. The guage reads about 125 on my trans empty.


It was in August outside temp 90 degrees.:eek:

my lly cooling fan runs way more than my lb7 fan ever did. It will drive you crazy. I have never had any temperature issues. everything normal there. I have actually pulled my 12,000lb 5th wheel up hills at an easy 65 mph with the fan running. So power for me is not the problem

My fan does not affect power. I just hear it switch on and off every once in a while. Typically, my temperature guage hardly ever moves from normal. Maybe when you get up to some very high temp (235?) the engine starts reducing power automatically because it senses it is about to overheat??? Just a guess.
Find a good dealer or pull your trailer up the hill with another truck - it definately sound like there is an issue with yours.

Biggermike, I don't know of any good dealers in the fresno area but, I am from Hanford and I purchased my GMC from Keller over by Hwy 198. There service writers Floyd and Joe are awesome they will take care of you! I am sure they help you with your overheating problem. Just tell them Jeff Lewis sent you


Jlew:cool: