GM 6.5 TD in an RV

[Lokel Yokel]

Hi, New to this website. I am shopping for an RV. I have two identical RVs in my sights. One is a 1998 with 6.5 TD. It has 60,000 miles. The other is a 1997 with a 7.4 liter / 454. It has 38,000 miles.

The diesel has been getting about 10 miles to the gallon in the RV. 16,000 lb vehicle. I think they come with something like 4:55 gears. It has the 4L80E tranny....did I get that right? I think that is what he said. It's a p30 chassis.

The gas motor probably gets 7 or 8 mpg.

I'm trying to decide which one to buy. The big block Chevy would certainly be a powerhouse and cheap to repair.

I saw a post that Robyn made to a fellow newbie. To check for leaks. And signs of water blowing out the vent on the radiator. Also have it set overnight prior to starting. The guy told me this thing (the diesel) starts right up and runs clean right from the get go.

I think either motor is cool. I will say this...if I ever have to pull one out...they tell me the motor must be hoisted out through the drivers windshield. I need a reliable motor long lasting motor. I will be climbing some hills with it. Maybe even Pikes peak?? Heading West with my family for a road trip.

Resale value is a consideration too. I figure many people would prefer a diesel come resale time.

I think I know how folks on this website will respond, but I'd still like to hear your thoughts. I'd like it to be a simple choice. I should also say...both motors are in stock configuration and I don't have money for mods on either motor.

Thanks!
Justin in VT

[JeepSJ]

I'll chime in because I own vehicles with both engines.

My 87 Jeep has the 6.5. My 87 CC Dually has the 454. The 97 454 is the Vortec series and puts out a decent amount more power than my 87 454.

I like both of the engines. I do give the edge to the 6.5. However, 97-98 blocks were probably the weakest produced for the 6.5 and they like to crack when you work them hard. But the heads and exhaust manifolds on the 7.4 like to crack also.

Banks makes a great kit for the 7.4 that really wakes it up.

Kennedy Diesel can give you a tune that 6.5 and really wake it up.

They both should be P30 chassis.

Personally, I think I would go with whichever coach had the living space that I liked best. If you are indifferent about the living space, then go with the diesel.

[rustyk]

I have had an AMG (Peninsular Engines) 6.5L TD in my coach for nearly 10 years. It's uprated to 230HP. The engine has been solid, getting 10-12 mpg. Accessories have been another issue - towed 4 times for failure of new parts. The predecessor OEM 6.5 had cylinder scoring and a blown head gasket when replaced.

I'd research the '98's engine - check the chassis build date. Many chasses sit at the factory for months before completion. I too would be skeptical about a late '90s 6.5 due to weaknesses. It sounds like a Safari Trek, which is a decent coach (if it doesn't have that wretched "Magic Bed").

My pusher has a 3.73 diffy, BTW (and 19.5" wheels). A 4.55 with a 4L80E and 6.5L would be rare, and limit cruise speed, especially with 16" wheels.

All that said, I'd prefer whichever coach was better-built, in better condition and had more complete, documented, service records. The condition of appliances (reefer, A/C, furnace, water heater, etc.) is important - replacement or repair of any of those could sap the fuel savings from the diesel over gaso.