My friend is on the road with a recently purchased 1985 Itasca Sunflyer. It has a GMC P30 chassis (light-duty truck, 23’ model RV). They were driving down the highway when suddenly the gas pedal was gone. There was no sound as it happened. The gas pedal just suddenly revved the engine instead of powering the rv. It could still go in low gear, at about 15 mph, but all the high gears were gone. They drove to a place to park, but the engine was overheating after a short distance.
Does that sound like the transmission needs to be replaced? How much would that cost? Or could it be something repairable, and how much would that cost? They’re in a small town with no garages open on the weekend so no diagnosis until Monday at the earliest. Any sound advice appreciated–thanks.
Your description is quite informative but without inspecting the transmission all I can offer is that the transmission will most likely need to be removed and opened and at that point a total overhaul is in order. Often a factory rebuilt (crated) transmission is a quicker and more reliable alternative than rebuilding the original. There is likely no quick fix to get home from this point. A shop capable of lifting the truck needs to be found to discuss the options for the owner. If there is a NAPA store in the area they would know which shops are equipped for such work.
The transmission is most likely a General Motors Turbo Hydramatic 400 which is quite common. Look online at O’Reilly Auto Parts for some ball park prices on a crated bebuilt transmission.
I haven’t heard yet what it was, but they only needed to replace one part! They said because it hadn’t been driven after it went out, the rest of the transmission didn’t need replacing. The total cost, including fixing a loose wire to the running lights, was $270!