Community Forums

Southernboy · 09-05-2011, 06:22 PM

After joining this forum I'm starting to think that the diesel engine is rather fragile , or some of the owners paranoid , I thought a diesel engine was known for its durability .I've never heard a trucker say oops i let it idle too long , better not run it unless your gonna take a long trip, better change all the fluids & filters twice a year or the crankshaft will fall out. I was really hoping that the engine would out last me , now i'm not sure about that.

RJay · 09-05-2011, 06:43 PM

First, welcome to the forum!

That's a pretty fair statement. RV diesels are used nothing like OTR diesels so we have to do things differently. But most of all it represents a high dollar investment so we want to protect our investment and avoid costly repairs. In addition most of us are retired and have nothing to do.

bluepill · 09-05-2011, 07:07 PM

The diesel is by nature a more highly stressed engine than the average gasoline engine, mostly due to the much higher compression ratio. That said, any decent manufacturer builds in the extra strength to make it durable.

As an example, a Chevy 409 gasoline truck engine that is run as hard as my 409 Cummins (6.7L) would not last for 4000,000 miles. The Cummins probably would last that long because it is built stronger (and that is reflected in the price).

In the used market, a diesel with 150K miles is usually considered a good reliable unit, but a gasoline engine with that mileage is considered near the end of its life.

JMonroe · 09-05-2011, 07:43 PM

I think some of the caveats about operating for short distances or periods of time have more to do with modern emissions systems than the engine. At a Cummins seminar I recently attended, as example, the speaker suggested that if the system started a particulate filter regen, keep driving until the cycle is over.

slickest1 · 09-05-2011, 08:11 PM

In my days of commercial driving my motto was drive it like you hate it. The biggest problem with RV's is they aren't driven enough. I like to exercise mine as much as I can but it still sits to much. Biggest thing is park it with fuel tank full, change oil and filters when needed. Some get carried away and some just like to putter with it because it's their baby.

B Bob · 09-05-2011, 09:40 PM

The two most common motors CAT and Cummins are hard as nails tough. Built much more heavily than gas motors by GM, Ford, or Chrys. CAT has told me that my C12 is likely a million mile motor. Likely way more miles than I have left.

Mekanic · 09-05-2011, 10:00 PM

X2 on the last 2 post. I have been told years ago and agree that the more often a diesel is run the less it needs babyed. Run it every day and you can't kill it.
I don't see any reason anyone couldn't go 2 years on a coolant change. or 10k miles or once a year on a (good quality Synthic) oil and filter change.
The diesels (or gas engines) used in RVs are not really designed for RV, no mattter what you are told. (if a engine is quieter it is the insulation not the engine) The RV market is too small to do that. The engines are designed for Trucks of about the same weight. and the only difference is mainly how and how often they are driven.
Yes I think some of the diesel owners are paranoid.

sdennislee · 09-06-2011, 01:20 AM

Idling at low RPMs is the issue with idling, carbon build up etc... We idle our diesels (Ford Power Stroke) here on the north slope of AK from November to March but we put them in high idle 1100 to 1500 RPMs, use a 1/4 tank of fuel every night.

When starting up I idle the MH (Cat C7) for a couple minutes while watching oil pressure, then kick it to high idle 1100 to 1200 RPMs and let it run as I ready up the rest of MH to head out.

As far as changing fluids, I fight with myself on that one. TO change fluids in the generator, transmission and engine it's #1500.00. The Allison guy says I'm good for 48 months or 175,000 miles with Transynd fluid. I like the idea that for $900.00 I can go 48 months.

bbeane · 09-06-2011, 03:48 AM

Quote:

Originally Posted by Southernboy

After joining this forum I'm starting to think that the diesel engine is rather fragile , or some of the owners paranoid , I thought a diesel engine was known for its durability .I've never heard a trucker say oops i let it idle too long , better not run it unless your gonna take a long trip, better change all the fluids & filters twice a year or the crankshaft will fall out. I was really hoping that the engine would out last me , now i'm not sure about that.

Your motorhome motor itself ( Block, heads , pistons, crank) will more than likely out last you, what will give you all the problems is the accessories the hang on the motor, the computer controls, wireing connectors,(if you have them) just like a gas motor. Just run it like you stole it, service it like the eng manf says, it will give good service. Just a side note most truckers don't own what they drive so they don't care about how they use or abuse it, they don,t have to pay for it.

Gary RVRoamer · 09-06-2011, 08:17 AM

The problem with the diesel longevity claims is they are not talking about trouble-free miles. A 2-4 million mile diesel will get rebuilt multiple times in that period. And diesel maintenance cost is high, as is the cost of most repairs. Replace a $2500 injection pump or a turbo charger and you learn that quickly.

And the 4 million mile diesel life says nothing about radiators, hydraulic pumps,fuel lift pumps or other diesel components that are not part of the engine itself. Those can and do fail periodically and are all expensive components.

Modern gas engines are 0.5-1.0 million mile engines, also far more than you are ever going to drive your RV. Besides, you can completely replace a gas engine a couple times for the price difference of a large diesel.

I'm driving a diesel because I like the performance, not because it is saving me money.

chasfm11 · 09-06-2011, 11:19 AM

A diesel engine has failure points. Sometimes, the makers add extra ones. Our Cummins 5.9 block, for example, was cast in Brasil and some of those castings were flawed, resulting in cracking around the exhaust manifold in use. There is the Cummins "killer dowel pin" story which was supposed to be limited to the pickup truck version of the engine. These stories and the more frequent failure of the fuel lift pump in the 5.9 have been discussed on forums, making it appear as though there are a lot of problems.

I hope that we purchased a diesel engine because of its reliability. To help to achieve that reliability, I do everything that I can to make sure the oil, coolant, belts, etc are carefully maintained and I only buy fuel from high volume truck stops, regularly changing the fuel filters. Beyond that, I think that it comes down to the luck of the draw. Most properly maintained diesel engines will outlast the coaches in which they are mounted. As Gary says, when it does fail, it isn't going to be cheap.

slickest1 · 09-06-2011, 04:11 PM

Quote:

Originally Posted by bbeane

Your motorhome motor itself ( Block, heads , pistons, crank) will more than likely out last you, what will give you all the problems is the accessories the hang on the motor, the computer controls, wireing connectors,(if you have them) just like a gas motor. Just run it like you stole it, service it like the eng manf says, it will give good service. Just a side note most truckers don't own what they drive so they don't care about how they use or abuse it, they don,t have to pay for it.

The side note might be true for some but if a trucker does not look after his rig wether he owns it or not it will not make him a very good living. Can't make money sitting in a repair shop!!

Mekanic · 09-06-2011, 04:57 PM

in the industrial plant where i work we only change fuel filters when there is a power drop. if you have plenty of power you have plenty of fuel flow.
We do however do scheduled oil, oil filter and air filter changes.

I have allways heard and agree the more often you run one the less often it needs maintance. My old 89 Ford tow truck I went for YEARS without a fuel filter change. every few months I would open the valve at the bottom of the fuel/water seperator and check for any water and that was it. it would just keep on a truckin.

wa8yxm · 09-06-2011, 05:03 PM

Times have changed.. I recall when I was a young lad you were advised not to let GASOLINE engines idle too long least the plugs get fouled,, Today with EFI, the computer makes sure they don't get fouled,, Diesels, however used to be able to idle them till the cows came home. Today's however, there is an issue with emission controls if you do that and peformance suffers till it's fixed (Not enough heat).

Times have changed.

The trucker never worries about short trips with his diesel cause he don't make any.

Many trucks have older engines that can still idle all day but there is no profit in idle.