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Shinytoaster · 11-17-2021, 08:26 AM

Hi - I've been looking for a Cummins 5.9 to replace my 454 that has no compression in 2 cylinders.

In addition to another post, I found the 5.9 in a AS land yacht that appears to be in great shape, but it's a rear mount/pusher.

I spoke to one diesel mechanic that said the mounts are all different and the bell housing is wrong (mounts to chassis), so it would be a huge task to modify...

Can anyone verify this?

The MoHo is a great price and almost worth it for the parts I need, but the engine and transmission are the priorities.

Thanks -
Pete

AirRowan · 11-29-2021, 07:04 AM

Anything can be done but the amount of work to do a gas to Diesel swap is huge. I have driven my converted buss for more then 36,000 miles and still have not made it worth the work.
I looked at the Cummings but it had a few drawbacks for me.
1.The length was the biggest problem It would mean cutting the floor out in front of the couch and losing space in the living room.
2. The noise; in a puller your sitting over the motor and the fatigue of sitting over the loudest diesel engine ever made (good motor don't get me wrong) when it is a pusher it is 35 feet away and under a mattress normally.
3. At the time (2011) there was no way to put the Allison 6 speed behind it. I dislike the Hydromatic 3 speed that the 454 came with. Gearing is a must if you are switching to a diesel with modern highway speeds and pulling anything behind your 18,000lbs Airstream
I wish you Goodluck with whichever way you go and I did enjoy parts of the project and I always enjoy driving the Airstream with more power then any other moho on the road ;-) my current project is re building a 1925 wooden schooner in Maine SailSchoonerHindu.com or Utube Hinduchartes.

Shinytoaster · 11-30-2021, 03:09 PM

Thanks - it's all pretty logical I guess. More work, louder etc... not a fan of too much extra work. I have to say that I didn't realize the pusher was going to need a cut out up front. More hassle than it's worth... tho' I do love the diesels... a lot.

Part of my dilemma is what the RV scene will look like in 10-15 years (or longer). I love the idea of electric conversion but $ way way to high... maybe in 10 years... maybe. It's all a bit academic with fossil fuels and electric power and no one really know if/when etc. I figured it's likely to be harder to replace heavy trucks so diesel will potentially be a better investment for the future c.w. gas... but I don't know.

What I do know is - 1. we want this to drive relatively failure free (drive train)... I can handle failures in the camper but breaking down on the side of the road gets real old (and expensive)... having had 7+ of those experiences just getting her home (from last shietbag owner).

Apart from 2 duff cylinders (very low compression) - she just cuts out after a slow down and will restart after 5-10 minutes. Not over heating (fixed that), not fuel delivery, not vapor locking - no one seems to know what the issue is. My guess it could be a combination of 2 bad cylinders with a badly behaving alternator (diode?). As such I want swap the whole beast out.

Outside of diesel - the top choice would be a 502HT with 4 speed tranny upgrade... theoretically a straight ($18K) swap (if I do it)... maybe a bit cheaper.

Figure I can fix this one up, just frightens me to spend the $10-14K (with tranny upgrade) and still have the stalling issue. Inclined to say f-it and throw the bank at it with a fully dressed engine.. not sure I'm brave enough though.

Apart from fuel milage and better resale value (diesel) - not sure how popular a big gasser will be in a decades time.

Cheers-
Pete

Quote:

Originally Posted by AirRowan

Anything can be done but the amount of work to do a gas to Diesel swap is huge. I have driven my converted buss for more then 36,000 miles and still have not made it worth the work.
I looked at the Cummings but it had a few drawbacks for me.
1.The length was the biggest problem It would mean cutting the floor out in front of the couch and losing space in the living room.
2. The noise; in a puller your sitting over the motor and the fatigue of sitting over the loudest diesel engine ever made (good motor don't get me wrong) when it is a pusher it is 35 feet away and under a mattress normally.
3. At the time (2011) there was no way to put the Allison 6 speed behind it. I dislike the Hydromatic 3 speed that the 454 came with. Gearing is a must if you are switching to a diesel with modern highway speeds and pulling anything behind your 18,000lbs Airstream
I wish you Goodluck with whichever way you go and I did enjoy parts of the project and I always enjoy driving the Airstream with more power then any other moho on the road ;-) my current project is re building a 1925 wooden schooner in Maine SailSchoonerHindu.com or Utube Hinduchartes.

Shinytoaster · 01-24-2022, 08:32 AM

It was awhile ago, so just an update for those interested.

The LY sold (I was dithering too much) - I believe $1200 for the complete LY with 12V Cummins - shoulda just brought it, the engine alone was worth $3-5K.

Oh well.. I'll keep looking.

jondrew55 · 01-24-2022, 09:02 AM

Thanks for the update. People will post things and folks will respond, but the subject never gets closed.

Quote:

Originally Posted by Shinytoaster

It was awhile ago, so just an update for those interested.

The LY sold (I was dithering too much) - I believe $1200 for the complete LY with 12V Cummins - shoulda just brought it, the engine alone was worth $3-5K.

Oh well.. I'll keep looking.

92landyacht · 01-24-2022, 10:09 AM

So, what's the status of yours? How's the engine now after a few doses of Sea Foam?

Shinytoaster · 01-25-2022, 04:23 PM

Well - it was nothing short of amazing.

She had a rough ideal and 2 pistons with pressure ~40-60 psi, after 3 lots of seafoam, and replaced all the plugs and leads.... the idle was much better and cylinder pressure was up significantly (~130 psi) I don't have actual numbers here, but high enough not to be panicking.

After some advice from other folks, I took a look at the distributor and found some evidence of corrosion, sooo - replaced that as well... upshot... wow. Very very smooth (for the 454). My wife and lad (25 yo) were there when I fired her up - both commented how much better she sounds... very happy.

I haven't done a leak down test yet, but hope in the next few weeks when it warms up.. and I can figure out how to get to TDC without cutting away the air dam under the front of bus/radiator. Last suggestion was to pull the cover away from the gearbox and turn the flywheel.

Over all tho' - just hoping there's no piston, ring damage.

Thanks

Pete

QUOTE=92landyacht;2572148]So, what's the status of yours? How's the engine now after a few doses of Sea Foam?[/QUOTE]

Shinytoaster · 01-25-2022, 04:28 PM

Just to add to the last note - I think I'm leaning toward keeping the 454 so long as any issues are north of the head gasket.

I'm still planing on picking up a 12v Cummins and rebuilding (if needed) over a few years and then do a swap later. Hopefully pick something up that will hold its value. Seems they are very popular.

Pete

Quote:

Originally Posted by 92landyacht

So, what's the status of yours? How's the engine now after a few doses of Sea Foam?

92landyacht · 01-25-2022, 07:05 PM

Good to hear that it's in much better condition now. Engines that have sat for a while will exhibit exactly what you've been seeing so it was a no brainer to try the magic fluid first.

Shinytoaster · 01-25-2022, 08:18 PM

The exception might be with really old engines. My father-in-law who has work on 1890's though 1960 's cars for 60+ years years has come across several occasions where the gunk around the pistons was the only thing holding any compression. A bottle of the magic stuff can be too good... lost most of the compression and the smoke like a coal train. Of course they should have been rebuilt anyway but he wanted to run them awhile... especially when parts have to be custom made $$$

Kinda makes me wish I'd put a camera down there and gotten before/after images (with bus).

Quote:

Originally Posted by 92landyacht

Good to hear that it's in much better condition now. Engines that have sat for a while will exhibit exactly what you've been seeing so it was a no brainer to try the magic fluid first.