Q. I have a 1997 Chevy crew-cab dually with a 6.5-liter turbodiesel equipped with a Banks Stinger kit to pull a 38-foot Titanium fifth-wheel trailer.
We recently completed a very successful trip out West with significant mountain grades up to 8 percent for as many as five miles. Uphill was no real problem, other than sometimes 40 mph was all I could make and still hold exhaust temperatures below 1,050 degrees F. Downhill I found that by selecting the right gear from my four-speed automatic, I was able to descend essentially without using my brakes. The engine and transmission did all the braking, and I was able to maintain 35-45 mph and not exceed 2,200 rpm on the engine. This seems to be too easy a solution for the horror stories I’ve heard about downhill runaway trucks.
Temperatures on the transmission were essentially the same as when the engine was pushing the truck, rather than the other way around. Is the procedure I’m using putting unreasonable loads into the drivetrain, especially the transmission?
— B.F., Bonifay, Florida
A. Not if the rpm and temperatures were as you described, B.F. However, most rigs this size (and therefore weight) encounter more downhill speed and rpm than that when they’re not using brakes on 8-percent downgrades; so be careful.
— K.F.
Ken Freund’s more than three decades of auto-repair experience and 20-plus years of RVing helped him author numerous books and articles on vehicle repair. In addition to RV Clinic and Performance, he writes the Powertrain column in MotorHome magazine. Ken has been a California Automotive VO-Tech and Smog-Test Program Instructor and an ASE-certified Master Automobile Technician.
