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Travel_glampers's avatar
Travel_glampers
Explorer
Feb 06, 2020

2009 Silverado 3500 HD Duramax LMM overheating

I have the above truck towing a 14,000 pound fifth wheel. When the truck was new, it overheated going up to Eisenhower Tunnel (11.000+ feet) in June. Both the engine and transmission (Allison) tempe...
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busterja21's avatar
busterja21
Explorer
Feb 07, 2020
i had an 08 dmax pulling about 13k up eisenhower and other CO passes. What i found works best is to put the tranny in manual shift,and keep the rpms around 2500 or slightly higher. engine temp sometimes climbs to 3/4 mark, but fan should kick in and bring it back down. seems counter-intuitive to the diesel to run at higher rpm, but it worked for me.

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