Going from Gas To Diesel(?)

[BEisler]

Ok, I am sure this has been bantered about quite a bit but thought I would start a new thread on this that may compile a lot of good input all in one thread.

I am close to making the move from gas to diesel (pusher). What do I need to know about the operation, maintenance and idiosyncrasies, etc. in making this change? For example, in cold weather do I need put a fuel additive in to keep the diesel from gelling (I believe this was an issue many years ago).

Some things I heave gleaned just from scanning previous posts are that diesel can be a little more costly for maintenance but easier to drive with much better handling.

Whatever you can think of that a diesel newbie should know - please share!

[WILDEBILL308]

holstein13, Just wondering about a couple of things.
“3. I now have to fill a DEF tank that I didn't have to do with a gasser. Every other fuel fill up requires me to top off the DEF tank. And it's on the wrong side of the coach.”
4. My fuel fill inlet is right behind my driver's seat so it's very easy to gauge where to stop at the pump. I can fill from either side.”

Why since you can fill from either side don’t you fill from the side the DEF tank is on?

24. “There are only three buttons on my transmission R N and D. There is also an up/down arrow and an eco mode but I never use either.”

That is ECON button and it will improve your mileage. Not knowing how and when to use those arrows may contribute to damage to your engine. It could also degrade your safety.



Bill the Iceman aka the op that 2013 Thor Daybreak is a nice coach. Most of the things you need to know have already ben covered. I would look at a nice used coach as you can find some amazing deals. If you can afford it I would by new enough that you do have a coach that uses DEF. The newer coaches can and are tuned to give more HP and mileage. I don’t know of a builder that makes a coach that doesn’t have enough power.
Your question about additives, I add an antigel as it is cheap insurance. Where I live it is possible to get into cold weather and still have all summer diesel number 2. I got caught by a cold front camping on the top of Raton Pass in NM. It dropped to -5 overnight. I was glad when MY motor started with no problem. You can read your owner’s manual on using the block heater.
Yes owning a diesel coach is a little more expensive. So what owning a gas unit is more expensive than tent camping. I don’t do it because it is cheap I do it because I want to.
Bill

[EricGT]

holstein13 wrote:
Ignoring the question of adequate power, here are some of the differences I've noted when I switched from Gas to Diesel.
...............................

I didn't copy everything but...
What an excellent post!

[RayChez]

I think predawn is blowing a lot of smoke in this forum. I guess he does not realize that the engineering department will install engines according to the weight of the coaches.

He claims he has the ISL 450 on his coach and can not pass trucks going faster then 70 miles per hour. LOL. Who wants to be driving up a six percent grade going 70 miles per hour anyways. But the reason why his coach can not do it is probably because it is a heavy coach, so that ISL even with the horses it has, it is still carrying a lot of weight.
So a coach that is 36'or 38' with a 350hp diesel should be perfect for its weight.

All I can say is that my coach has the 3126-E Caterpillar and I have traveled all around the country with no problems as far as power goes. First towing a Honda Pilot weight of 4200 lbs and now a Honda CRV and I can not even tell they were behind my coach. I also noticed that those Cat engines it takes about fifty thousand miles before they are broken in. I have 60K miles on the engine now and my coach is running at its best. One thing that I did notice gave my coach a lot of power was changing the air filter from a Farr to a Rancor filter. Wow! a lot of difference in power.

[holstein13]

Ignoring the question of adequate power, here are some of the differences I've noted when I switched from Gas to Diesel.

1. Diesel fuel is more expensive than gasoline and this may or may not be offset by better mileage. Mine isn't, but my coach alone is close to 54,000 pounds.
   
2. I now fuel up at the truck stop diesel pumps. I've got a 200 gallon tank and filling it up at the car pump at 10 gallons per minute would take 20 minutes.
   
3. I now have to fill a DEF tank that I didn't have to do with a gasser. Every other fuel fill up requires me to top off the DEF tank. And it's on the wrong side of the coach.
   
4. My fuel fill inlet is right behind my driver's seat so it's very easy to gauge where to stop at the pump. I can fill from either side.
   
5. Air brakes are super easy to operate. Takes less pressure to engage than my old hydraulic brakes.
   
6. The ride is very quite up front. It's a night and day difference. I can easily have conversations with my wife (although we rarely do) or listen to music or anything else.
   
7. The air ride suspension is much nicer than my old suspension. 95 percent of the bumps and potholes are easily absorbed by the suspension.
   
8. I need to air up my coach and let the ride height come up before leaving. I make sure my ride height is adequate by walking around the coach and checking when I first start up.
   
9. Conversely when I stop the coach and put down the jacks, I need to make sure the tires are straight so that the wheel wells don't come crashing down on the tires.
   
10. If I tried to make a turn before the coach was at ride height, I would surely damage the tire wells. I've witnessed it on another coach.
    
11. When I want to let the coach idle, I must bring the idle up to 1,000 RPM to prevent damage to the motor.
    
12. I just bought a fuel filter for the coach to keep as a backup and it cost me over $100.00
    
13. I'm told that bad fuel is a real possibility with diesels
    
14. My air filter has a gauge that tells me if it's dirty and needs to be replaced.
    
15. My coach is equipped with a supplemental air leveling system that keeps it level on roads with a crown or curves. I can even level and put out the slides using this system without the jacks.
    
16. My alternator is so powerful it can even keep the batteries charged while one roof AC is running. No need to run the generator on route.
    
17. My generator is now diesel as well and takes a few seconds to warm up when I press start.
    
18. I've got an engine block heater installed but am told I wouldn't need it unless temps drop dramatically below freezing at departure time.
    
19. My engine and transmission weigh about 7,000 pounds alone. Everything on this engine is huge, especially the air filter and exhaust system.
    
20. Each cylinder puts out 100 horsepower.
    
21. My air horns sound dramatically different than my old electric horn. It's more like a train now and gets people's attention.
    
22. My coach came with a diesel hydronic heating system that keeps my shower hot no matter how long I run it. It uses engine heat while on route to heat the furnace.
    
23. The parking brake is a plastic knob that I must pull to activate. It can hurt my hand to pull on it because it has a percussive effect.
    
24. There are only three buttons on my transmission R N and D. There is also an up/down arrow and an eco mode but I never use either.
    
25. To park, I put my foot on the brake, put the transmission in Neutral, apply the air parking brake and then release my foot from the service brake in that order. Otherwise an alarm sounds.
    
26. To get moving again, I put my foot on the service brake, release the parking brake, then put the transmission into gear in that order. Otherwise an alarm sounds.
    
27. The engine seems to be as easy to start and stop as my old gasser. I pause for a few seconds before starting it to allow the glow plugs to light up.
    
28. The entry door is now in the front of the coach so I walk around the passenger seat every time I enter the coach. It was less awkward in the old gas coach. Also, the door needs to be slammed before departure to make sure it is properly sealed against wind noise.
    
29. There are truck repair shops virtually everywhere along the major highways. Lot's of official Cummins authorized service centers as well. They are easy to get in and out of.

I hope this gives you some of the insights you were looking for. It's a shame that the horsepower issue keeps getting debated endlessly on this forum.

[et2]

If you're within the designed specifications of the MH and the engine is well maintained and in full operational condition then it's a no brainer. If you like it go for it. All MH's slow down on certain grades. It isn't a race. Everything else your hearing is opinions about horsepower. Drop a gear if you need to, maybe two or three. Forget about the rest.

[WILDEBILL308]

BEisler wrote:
CORRECTION . . . . the diesel we are looking at is 300 HP Cummins, not 340. Should we walk away from this?

Why?
Bill

[Cbones]

I will throw my 2 cents into this thread. I have driven over 90K miles on my ISB equipped Discovery loaded to 32K lbs with a 5K Jeep Grand Cherokee toad. There is no mountain in this country that I could not top. I can run 70 mph all day long pass semis up mountains with ease. Sure I have driven an ISL equipped Revolution, and yes it has slightly more power, but nothing crazy. I travel in tandem with my buddy in his Revo with the ISL. I have absolutely no problem keeping up with him. These are not meant to be race cars. They are just designed to get you from A to B. Almost all motorhomes gas or diesel will get you where you want to go. I would worry less about the size of the engine than the features that you are looking for. There are thousands of Discovery's, Phaetons, and Ventanas out there with ISBs that run all over this beautiful country without any problems getting up all the big hills west to east.

[kalynzoo]

I just purchased my first diesel pusher, and Allegro Red (rear engine diesel)38ft with a cummins 340. My previous 35+ years of RVing have been in gas coaches, a 454, and Ford V10, and a Workhorse 8.1, respectively. My current experience is with only 1000 miles on the diesel. WOW, how nice it is. The ride is infinitely smoother on California's rough neglected freeways. It is quiet, my wife and I can have conversations while driving, and I can actually hear the radio! even going up steep grades. Going up the Grapevine, a really long 6 to 8% grade I had no problem maintaining 45 to 50mph with the same quiet soft ride. Truthfully, I could gain more speed with the gas 8.1, but I would rev at 4k rpms and the noise level was pretty rough. Going down the Grapevine was a total pleasure. With the engine brake engaged I went down the 8 mile straight grade at 45mph without ever touching my brake. With the gas RVs I would constantly tap the brakes, and at the bottom I would pull out at the first town (at the bottom of the grade) and let the brakes cool while we took a little personal break.
In conclusion: If budget is not in the mix, diesel is the way to go. Of course diesel is more expensive for most people, in base cost, in maintenance costs, and any saving in fuel probably would not apply for the low mileage most RVers put on their coaches.
JMHO

[Norm___Deb]

I said "I got around Colorado just fine". I would not attempt to tell anyone about their situation! Just relating my rig and my experiences. 'Nuf said, BY!

[Norm___Deb]

I said "I got around Colorado just fine". I would not attempt to tell anyone about their situation! Just relating my rig and my experiences. 'Nuf said, BY!

[Norm___Deb]

Well, I've got a 26K diesel, with a 330 turbo cummins, pulling a toad and I got around in Colorado just fine. Not fast up the mountain but I still got there. How much time will you spend going up?? Another interesting point....in the mountains, I can go up the hill, no matter how steep, faster than I can go down. Yep, the brakes are the main issue in the mountains. Been there, done that!

Diesel vs Gas. I need the diesel! However, remember the old saying if you buy the diesel, "better bring some money to town". Your gonna need it.

[hanko]

you'll find its twice the money, but not twice the fun.

[BEisler]

CORRECTION . . . . the diesel we are looking at is 300 HP Cummins, not 340. Should we walk away from this?

[Trackrig]

We have a 350 HP Cat C7 in a 39' Fleetwood Excursion. We've been to Alaska and back, all through the Rockies in western Canada and up and down the western US twice with no problems. That includes entering the Tetons from the west side (8 miles of 10% grades) Eisenhower Tunnel, and southern Utah - a few 14% grades. Just keep your RPMs up and make sure your radiator and intercooler are clean.

As far as cold weather... If you're in a pick up truck where #1 fuel is being sold, yes you should use Power Serve. It does lower the poor point of diesel, but more important it puts the lubricity back in the fuel that that was lost as part of the process to make #1. The injection pumps in diesel pick-up trucks are very sensitive to lubricity. They're running about $6K to replace and a lot of them get replaced up here every winter. I'm not sure how #1 fuel effects the larger DP engines as far as lubricity goes? I carry several jugs of Power Serve in my DP and if I get to where they're selling #1, I'll use it as cheap insurance.

If you were going to park it in colder weather, yes I'd use Power Serve to help with the starting. Also know how to use your engine pre-heater. And hopefully you will have an engine heater. Find the switch for it, sometimes the mfgs like to hike it. It will run on 120VAC, so you'll need to have the MH plugged in or be able to start the generator to power it. The gen set usually starts easier in cold weather than the main engine does just because it's a smaller engine. Also if it's cold out, and the generator will start, start it to run the main engine heater and at the same time it will raise the charge in the starting batteries. Depending on how cold it is, you may have to let the engine heater run for a couple hours. Once you get used to your engine, you'll be able to tell if it's going to start or needs more heating. In cold weather, if possible, you should also try to park it so that you can get another vehicle close enough to the batteries to jump it.

Bill

Bill

[naturist]

It is true that fuel distributors pretty much take care of the cold weather performance issues, but there are still cold weather issues if you don't pay attention, for example, driving north with a tank full of southern fuel, or if you buy fuel from some lonely station that maybe orders fuel once a year. In either case, a shot of Power Service anti-gel might be in order, "just in case," and "it can't hoit nuthin'."

It must also be noted that you can size an engine too small for the job at hand regardless of whether it is gas or diesel. The acid test is to drive it up a steep mountain and see what it does. It is true that diesel engines have a higher thermal efficiency, meaning in practical terms that they will burn less fuel to drag a pound of "stuff" any given distance, but this too is a function of the specific engine sizes involved.

There are a couple things folks used to driving gassers need to know when they find themselves behind the wheel of a diesel. First is that diesels do not react well to being run out of fuel. In the old days, that used to destroy the fuel pump and injectors, which not so much any more, but it is still hard on them, and getting one that has been run dry restarted is a HUGE pain in the butt, wise grasshoppers take care to never do that. A second thing is that you have to retrain yourself to pay attention to putting DIESEL fuel in the tank and not refueling while on autopilot, which has been known to get you a tank full of gasoline. THAT is a very expensive mistake to make, btw.

As for your question about the 2014 rig with the 340 HP Cummins, I refer you to the acid test above.