DEF diesel engines

Carringb, our 2008 Monaco Dynasty had the Particulate Filter and no DEF which was the second year that the PF was required.

We drove our 425 HP Cummins for almost 70,000 miles in 7.5 yrs. No problem with the Particulate Filter as it would run a regen cycle about every 8K-10K miles. At 40,000 lbs., we averaged about 7.5 mpg's.

I think if I were looking at coaches in that time frame, I would look at the history of that particular coach/engine and then make my decision. I wouldn't just rule them out automatically.

MM.

Mr.Mark wrote:
Carringb, our 2008 Monaco Dynasty had the Particulate Filter and no DEF which was the second year that the PF was required.

We drove our 425 HP Cummins for almost 70,000 miles in 7.5 yrs. No problem with the Particulate Filter as it would run a regen cycle about every 8K-10K miles. At 40,000 lbs., we averaged about 7.5 mpg's.

I think if I were looking at coaches in that time frame, I would look at the history of that particular coach/engine and then make my decision.

MM.

I agree my 425 Isl works just fine and I know a lot of people with 2008=2009 isl,s and no one has any problems

To connfuse things even more, Moaco bought up a bunch of extra 06 engines... I've seen 09 MHs with a 06 engine.
If you ever need a new Partical Filter... hang on to your wallet although less of a issue for a MH that will not see much over 150K miles.

Ken, one advantage to a non DEF engine in Winnebagos is there is room for a basement heat pump. The Winnebagos with a DEF system used the area where heat pump basement is for a DEF tank and moved there A/C system to the roof top! Great Question!

Mr.Mark wrote:
Carringb, our 2008 Monaco Dynasty had the Particulate Filter and no DEF which was the second year that the PF was required.

We drove our 425 HP Cummins for almost 70,000 miles in 7.5 yrs. No problem with the Particulate Filter as it would run a regen cycle about every 8K-10K miles. At 40,000 lbs., we averaged about 7.5 mpg's.

I think if I were looking at coaches in that time frame, I would look at the history of that particular coach/engine and then make my decision. I wouldn't just rule them out automatically.

MM.

The Cummins DPF was quite a bit more reliable than the Navistar engines with DPF. But some still had issues. I would trust a high-milaege Cummins with known history. If anything, high mile coaches are driven longer and harder typically, which is actually better for your DPF. When our DPF trucks started having issues (especially with the turbos) we changed company policy to "drive it like you stole it" and overall operating costs went down. Driving too gently causes frequent regens, which uses more fuel than driving it hard!

carringb: I think you are confusing HD trucks and RV's. Class 8 trucks use a more robust DPF system. They also have many more regens. In one year a Class 8 truck will travel 150,000 miles. A MH might go 7 or 8,000. At that rate an RV DPF would be more than 20 years old before needing any emission repairs. Navistar is a whole other story as the engineers were arrogant and dumb. They insisted they had developed a system that would be better than the Cummins unit. Of course they were lying! The Navistar engines were and are junk ( mF13 and up). Early Cats with DPF's are just as bad. Our 08 Dynasty ith an ISL has about one regen per year! Still as strong as ever. I might add that emission problems will get worse very soon. The EPA, CARB and impossible to obtain fuel mileage demands from the Gov. will cause nightmares.

Moisheh

Actually the DEF fluid is Urea which turns to Ammmonia when heated which crystalizes in your lungs when you breather it so 20 years from now the Govt is gonna go OOOPSY!

JumboJet wrote:

wolfe10 wrote:

JumboJet wrote:
DEF is introduced in the exhaust stream and has no effect on engine power.

While the statement is true, it may be a little misleading.

Because of DEF, the engines can be tuned for more power and better economy.

Very similar to what happened to gasoline vehicles between 1974 and 1975 when catalyst converters were added.

I was referring to the post title "DEF diesel engine". The engines are designed for leaner burn but produce a nasty exhaust that the fluid converts to water and nitrogen via the SCR.

Are the newer engines that require DEF actually providing better economy or just tuned for more HP?

Bret's statement is exactly accurate. When the pre-DEF engines were tuned for maximum power and economy it drove the EPA guys nuts because the products of combustion were causing pollution which could be tuned out on these same engines. The down side of that was that when they were tuned for better emissions, power went down and they actually got poorer mileage. Many who had a Cummins engine that was made in the 1-3 year period before DEF came in came in will probably remember the recalls issued to re-flash the ECM that were common. Each time it happened mileage dropped. In fact, if you had your rig in the shop that was engine certified, you got the re-flash without them telling you they did it or even consulting you. I spent a lot of time on the phone with Cummins and with service people about this. When the DEF engines first came out one of their selling points was better mileage and more power. This didn't have anything to do with the DEF (as many have said, DEF is only used in the exhaust stream after the exhaust leaves the engine) but what it did was enable engine makers to again design and tune for power and economy without the EPA clowns beating them about the head and shoulders. Was this better or worse? You decide how much pollution an RV contributes to the world smog when most are driving 3000 - 5000 miles a year and how much the extra equipment weight, complexity and maintenance are worth to you.

If you can find one that does not use DEF that fits your needs, BUY IT! I had one of the late model Cummins pollution specials. It spent as much time in the shop as it did on the road. Check engine lights,clogged DEF,new ECMs,new EGRs, reflashes,wiring harness and on and on. Every time it went in and was "fixed", it lost fuel mileage.
The new EGR valves recirculate so much exhaust that they have to be liquid cooled.

The truck dealers and towing companies are very busy with these new pieces of gov. mandated junk.

az99:

So true! The company I drive for, over the road, has had MANY newer trucks into the shop, for days at a time, trying to trace down emissions/DEF problems! Waaay more than normal engines. Eventually, they will get the problems sorted out, but by then, NEW controls will be called for, and the problems will start all over again!