Long time RV-ers considering an older Prevost

[Fratto]

I met a couple in a 40 footer with an 8V92 at Prevost Goodlettsville. They love it and have had no issues :-)

They think of getting something newer from time to time then change their minds and keep what they have.

[stimpee]

I just got back from a 3 week, 7 state, 3500 mile trip and no issues at all. My 8V92 pulled all the grades, including HWY 80 out of salt Lake and the long pull leaving Nevada on HWY 15. I was pulling my 2021 Ford Ranger.

Thanks for the info and feedback. We went over to Olympia last week and had a great experience with Brad showing us around. George, we looked at your former Royale and it is very nice. The trip there and looking at a few lower priced units sold my wife on the “old” Prevost.

I have studied a bit more about the various converters and at this point I think it will really come down to finding the right floor plan and condition at the right price.

We are very seriously considering an older 40 foot 8V92 coach at this point. We have seen a few very nice sub 100k coaches and feel that might be a really good entry point for us. The key will be finding something well maintained. We are confident tweaking or updating the interior a bit as needed.

Seems like the only significant concern for me on the 8V92 is making sure the cooling system is solid, and accepting the increased fuel usage over the series 60.

Keep sharing thoughts!

[Fratto]

Start looking for a good old school mechanic. From what I hear these are fine motors, but the number of folks that know them inside and out are dwindling. I am sure that some on this forum that have them can point you in the right direction.

[stimpee]

Start looking for a good old school mechanic. From what I hear these are fine motors, but the number of folks that know them inside and out are dwindling. I am sure that some on this forum that have them can point you in the right direction.

i will do so. I am in the greater Nashville area so that might help a bit. I am also less than 3 hours from East Tennessee luxury coach. The more I am learning, the less I am worried about the possibility of the 8V92. It might just be the sweet spot to get us started. We will see.

[prevonubie]

Hey Steve,

I have a 93 Marathon with the 8V92 TA and I love it....just ensure you have all the maintenance records and one sure way to determine if the coach has been well maintained is if they have all the manuals, and a extra parts i.e. filters, relays, belts, etc. I do all my own maintenance and here in the Chicago area I have access to a couple old school 2 stroke diesel mechanic's at Interstate Power. I reach out to them when I need help along with the great guys here on the POG site. You won't go wrong with the 8V92 if its in good shape, in my opinion its bullet proof. Also for the cooling system, yes you are correct make sure you look carefully at the radiator, if its original you can be sure you will more than likely need to have it rodded out or replaced soon. I purchased mine in 2021 replaced the radiator in 2022 after I noticed it had missing and corroded fins when inspecting everything prior to a trip cross country. My son and I got it out in about 4 hours and back in and running in about 6 hrs. (a few days later of course after getting it back from the rad..shop). Another thing...if you hear about how the 2 stroke diesels leak oil....that's not true, if you find a leak you just need to replace a seal/gasket. I have no oil leak issues and if/when I see one I fix it. Just replaced the valve cover seals earlier this year from a small leak I noticed on the right side of the engine...just replaced them both....Good Luck! You won't be disappointed if you find the right one!

[No Name]

This may help some here, parts, resources, etc..

I think the 8V92 is great, while most run from it. Look at boatdiesel.com for info on the 8V92 - they were used in several 50ft class yachts, especially the venerable Hatteras 53 MY that is a massive favorite amongst the cruising couple owner/operators (no capt, no crew). Also dieselpro.com is a great parts resource for the DD's as well as they have hour+ long videos of how to disassemble and rebuild them on the Tube. Know the differences between the 71 and 92 series. The long range cruisers prefer the simplicity of the dry sleeve 71 while the 92 has more displacement & power, it has fragility issues with cavitation in around the sleeves. Most boat engine issues are directly from neglected/differed maintenance, bad house keeping, cheap fluids and parts and owner abuse. While they will rev to 2400rpm, they don't like it and will destroy themselves. They like 1200-1800rpm all day long - and keep it under 2000 whenever possible. Consider that when looking at gearing and speed down the highway. Sportfish boats where the capt's set a 2100-2150 rpm cruise get around 2000 hours out of an engine before a rebuild is required. Long Range Cruisers that loaf their boats around 1400 rpm get 8000+ hours out of the engines. As a rule, any DD at 4500 hours or more is considered timed out and ready for a rebuild - doesn't mean they are shot, but boat value wise the price takes a hit. In the marine world a rebuild is generally $4k/hole (parts & labor) on practically any engine. The DD 2-strokes parts are relatively cheap, but due to them having basically double the parts (total systems) of a 4-stroke electrically controlled engine, you make up the difference in additional labor. DD 2-strokes give the mechanically inclined a ton of options, cheap. Swapping out injectors, adjusting timing, etc... All things to make your DD go from mild to wild. Regardless all DD 2-strokes that are E rated (high performance boats, yachts, patrol boats, etc.) are essentially 1hp per 1 cu in. so an 8V92 E rated marine DD would be between 700 & 750hp. The commercial continuous duty ratings will be down in the 400hp range and governed to 1800rpm. There is the secret with the ratings, they do reduce injector size but mainly reduce the rpm from 2400 (E), to 2300, to 2100, to 1900 to 1800 (A).

Usually truck engines are detuned significantly because they A: do not have an endless supply of cooling capacity from the ocean. B: are operated in constant start/stop/load/rest environment on the hwy, where a boat simply sets the throttles with a relatively constant load condition. Most good capts run their engines based upon load percentage vs RPM/speed. Know what the BSFC of your engine is and try to run right at that RPM - the engine will last forever, produce the most tq/hp per rpm and yield the best fuel economy (it's usually right where the Hp and Tq curves intersect. The DDs produce gobs of Tq down low and drops off sharply as RPM exceeds.

As mentioned in precious posts, we came from the boating world, unless you can't tell. To 2nd the post above, no engine should leak. Some engines have design issues that get improved with each version to mitigate leak prone areas. The evolution of the Cat 3406 A, B, C, (no D) E models all had changes to the head gasket/spacer plate design as well as the peanut cover on the front. I would definitely watch for smoking and check oil level daily - with the supercharger these engines can produce enough blow by on a severely worn engine to start eating themselves/running on the crankcase oil vs diesel from the injectors - one main reason they have manual flapper valves to close the air intake.

[Ck2hans]

“with the supercharger these engines can produce enough blow by on a severely worn engine to start eating themselves/running on the crankcase oil vs diesel from the injectors - one main reason they have manual flapper valves to close the air intake.”

Years ago (in the early 80s) when I was in the U.S.Coast Guard I stood on the dock and watched a 8V92 inhale itself. It was a high hour used engine in a patrol boat that started to run away. They shut off the fuel so it started using the crankcase oil and kept running away. They closed the flapper and it inhaled it, they shoved rags, towels and anything else they could down the intake. It inhaled everything and kept running away until it finally threw the connecting rods through the block. Made a big noise and a lot of smoke. Glad I was standing on the dock, will never forget seeing that.
Chuck

[Fratto]

Wow, such great information! I had no idea that they were used that much in the marine industry. Too much fun.

Thanks for sharing and bringing different perspectives.

[PrevostNewbie]

“with the supercharger these engines can produce enough blow by on a severely worn engine to start eating themselves/running on the crankcase oil vs diesel from the injectors - one main reason they have manual flapper valves to close the air intake.”

Years ago (in the early 80s) when I was in the U.S.Coast Guard I stood on the dock and watched a 8V92 inhale itself. It was a high hour used engine in a patrol boat that started to run away. They shut off the fuel so it started using the crankcase oil and kept running away. They closed the flapper and it inhaled it, they shoved rags, towels and anything else they could down the intake. It inhaled everything and kept running away until it finally threw the connecting rods through the block. Made a big noise and a lot of smoke. Glad I was standing on the dock, will never forget seeing that.
Chuck

That is a cool story

[Nightwind]

Well I bought a 94 Liberty Elegant lady that had sat for several years. So far it has been an excellent buy as it was maintained much better than most prior to being parked. I'm having my diesel shop go thru the diesel parts and my coach people ( ALL LOCAL) go thru mine. Fortunately my two shops have owned and currently own similar units, a blessing. So far I'm way under the prices for a similar coach (yr and converter) I expect to be done with it later this year and plan to use it on shorter runs until I feel all of the bugs are worked out. Then I'll stretch out my trips. Since I am in NO hurry I can take my time and more importantly my techs can as well which helps out on the labor. If you take your time and go thru EVERYTHING once controlling the cost, then you'll know what you have without the 1 mil price tag. JMHO