Thermoguy wrote:
I know a Cummins diesel engine should go for 400K plus miles but why are RV’s needing rebuilt with under 100K miles, is it because they site too much and the engines are not designed to sit? Or, is it because they are overworked by the large home they are pulling and undersized motors? I guess the same is true for gas Class A rigs, any opinions on this from someone who has had to rebuild a motor with low miles?
I haven't personally had to deal with rebuilding a diesel in a motorhome with low miles, but I think the lack of use and poor maintenance is part of the issue with low mileage engine failures in diesel motorhomes. There is also a broad range of durability among the various sizes of Cummins and other diesels you'll find in motorhomes. The 5.9 and 6.7 B series motors are fantastic engines, but in a 40 foot pusher pulling a 10K trailer, they are right at their limit. But the pushers with the "big block" diesels commonly found in class 8 trucks (in the 12 to 15 liter range) will last 1,000,000 miles with proper maintenance, and a 40K rig pulling a 10K trailer is nothing for these engines. But with those big engines comes higher purchase, fuel, maintenance and repair costs if something does break.
