I'm looking at ads for motorhomes and it seems that many make a point of advertising that the diesel motor, be it Cat, Cummins, or Detroit, has been rebuilt and the rig doesn't have that many miles on it. Here is a current example from a 1984 coach with 135K on the odometer - "Power train (Detroit 6V92TT and Allison 5sp auto transmission) were rebuilt in 1990 and just had a top end rebuild last year."

Why would a 1984 model Detroit with only 135K on the clock need rebuilding unless it was abused? I mean, I'm somewhat proud of the fact that my 5.9L has 291K on it and had not been rebuilt and I hope that it makes it to 4-500K without a rebuild. That's the point of these medium and heavy duty diesels.

Why the early rebuilds on motorhomes?

 

Medium duty engine in a heavy duty application.

 

a 6v92 isnt a med duty engine. i had a road tractor with 750000 miles and hadnt been rebuilt when it was destroyed by a car.
maybe seating for long periods of time

driver612

 

Lack of proper break in, & poor maintenance, along with driving habits, will kill any diesel engine.

 

probably ran them out of oil or poor maintenance .with a leaktroit diesel I would bet ran out of oil . I seen lots of them over heated too!

 

nothing medium duty about any 92 series engine. TONS of transit buses and firetrucks still run 6v's to this day. its more like a heavyduty engine in a medium duty application. no motorhome needs an engine like that. unless it was a converted bus that had it already/

like buddy said maybe Mr Joe Q. Guy has abusive driving habits.

 

So how often does a 92 Series engine need to be rebuilt?

 

My guess would be long periods of sitting, and oil changes based on mileage without regard to time.

Condensation inside the crankcase, plus blowby contamination being allowed to turn to acid, that kind of stuff?

 

One of the big problems with these rigs is the owners don't put many miles on them, so they think they can go 100,000 miles without changing out belts and hoses. What they don't think about is that these things need changing every few years even with low miles. They go out and run a 1000 mile trip, forget to pay attention to temp gauge and bam, tow truck and rebuilt engine, or as above new top end due to cracked heads.

 

I suspected excessive idling to be a factor and this confirmed it . http://www.rvmechanic.com/current_ca...read_full.html

 

If they are treated like my FIL does his, it sits 9 months, then gets fired up and held to the floor for 1200 miles nonstop, parked for a month, then fired up and held to the floor for another 1200 miles nonstop and parked another 9 months. Repeat process next year.

 

prob none of above,tractors, farm trucks,const. mach. all sit for extended periods and are used hard. most of these repairs are done because the ownwer of the rv was told look at this dirty oil you need a rebuild ,and it gets done.

 

Overheating! A bad cooling system design leading to bad accessibility for checking coolant and engine oil quantities and if an automatic, the transmission oil level as well. The engine compartment is secondary to what the buyer sees inside. I've heard of quite a few gas class A's with engine failures at 6000ml. Usually bottom ends ground out from cooked engine oil.

 

Well, several logical possibilities have been mentioned. Thanks for the ideas.

I'm currently looking at a 1992 coach with a 6v92 that has 133K on the odometer and 3334 hours on the hour meter. Unfortunately, the seller doesn't know any history on the coach since they're selling it for their dad who now is in a nursing home but we do know that it's been sitting for the last 2 years in indoor storage. By my calculations, that comes to an average of just under 40MPH average if there were no idling. Would that be considered "excessive" idling or does that seem reasonable?

 

there is a bulk fuel delivery CO. in so. cal that had a magazine article written about a fleet of silver 92s a few years back,the lowest mileage one had 700K the highest had 1.4 mil. and the heads were never off trucks were still hauling 9000 gal. fuel all over calif.