“Are you sure?” This seemed to be the most common response when Dave Friedli would talk to friends, shops and mechanics about the overheating issues he was having with his 2003 GMC Duramax. It’s not that no one believed him, but rather, LB7 trucks aren’t typically known for having overheating issues when towing.
While every truck off the production line eventually gets tagged for having some type of an issue, those who use their LB7s to tow have generally had success with no real overheating concerns across the board. Of course in this specific case, this truck wasn’t exactly a stock LB7 anymore.
In an attempt to create the ultimate tow vehicle, the truck owner upgraded to an ATS Aurora 3000 turbo, 50hp injectors from Dynomite Diesel Performance, Diamond Eye dual exhaust, an EDGE Insight CTS with EFILive, ATS intake, as well as several other performance modifications including a rebuilt transmission from Adrenaline Performance that left his GMC—complete with a Superlift 6-inch lift sitting on American Force Wheels and Mickey Thompson tires—at 534.9 horsepower and 1127.8 ft./lbs. of torque. But despite all the effort that went into the performance, the truck was having major towing issues.
“My EGTs were all over the place and it was very frustrating,” recalls Dave. “At the time I was also having trouble with the coolant temps.”
Wanting to exhaust all his options before admitting it might be the heads that were causing him grief when towing his 30-foot fifth wheel camper through the mountains, Dave began by replacing both thermostats, flushing his radiator and adding new coolant, adding a new cap, a new clutch fan and anything else his friends would recommend. But no matter what he tried, nothing could keep his engine temperature from spiking on the hills.
After yet another failed attempt to keep his temperatures down following a trip, the truck owner pulled onto his driveway and that’s when coolant began to gush. The writing was on the wall: it was now time to find a shop that was capable of doing the one major rebuild he was hoping he would be able to somehow avoid.