DPF vs. NO DPF (75hp edition)

[MinnesotaMorg]

Hi there,

I am new to the tractor game, I am trying to take my time and absorb as much information I can before I pull the trigger on a tractor.

Can someone explain to me why some tractors (MF 4707 / NH Workmaster 75) don't need a DPF and others in the same class (5075e / M4D-071) have a DPF? Everything I can find indicates that DPF is not desirable and will only serve to increase your initial cost and maintenance over time.

The Kubota salesman I talked to said new holland might be using engine credits or something. But would that mean that the consumer is just better off taking advantage of the companies using those credits? Assuming everything else is equal, is it in my best interest to choose a tractor with no DPF?

Thanks for coming to my ted talk
Morgan

 

[jeff9366]

Most tractors over 26-horsepower use a Diesel Particulate Filter (DPF) to meet Tier IV emission standards. This is not "news".


The less used alternative emission technology is Diesel Oxidation Catalyst (DOC). In a DOC system exhaust heat is elevated all the time.

Both the DPF and the DOC are honeycomb ceramic filters.
The DOC forces engine exhaust over a honeycomb ceramic structure coated with platinum, palladium, and rhodium catalysts. These catalysts oxidize carbon monoxide and hydrocarbons into carbon dioxide and water at hot exhaust temperature.

Diesel particulates must be burned. THERE IS NO FREE LUNCH.

Tire wear and tire replacement will cause as many headaches and more expense than DPF for most long term compact tractor owners who comprehend their tractor's Operator's Manual and follow DPF procedures.




Tractors over 75-horspower require Diesel Exhaust Fluid (DEF).

Diesel Exhaust Fluid (DEF) is a non-hazardous solution, which is 32.5% urea and 67.5% de-ionized water. DEF is sprayed into the exhaust stream of diesel vehicles to break down NOx emissions into harmless nitrogen and water.
DEF is not a fuel additive and never comes into contact with diesel. It is stored in a separate tank, typically with a blue filler cap.

 

[5030]

All the manufacturers had what is referred to as emissions credits where they were exempt from the T4 mandate until they produced and sold x numbers of units and then the credits were used up and compliance became mandatory. They were put there to allow them ample time to adapt their tractors to the mandate. Some of the low unit manufacturers like Mahindra for instance may have credits yet but the volume manufacturers like JD and Kubota exhausted theirs a while ago and have to be in full compliance now. I believe Massey still has credits as well as Mahindra and maybe Branson as well.

They all had to be in compliance with the T3 Interem standards as there were no credits issued for that, only T4 final. Understand, the T4 final mandate only applies to units with more than 26 pto horsepower but the next upcoming T4 mandate will be for ALL tractors regardless of power output and will also apply to small gasoline engines. Your lawnmower will have to be equipped with a cat as well.

I happen to own a chainsaw with a cat on it and because it's gas powered it works just fine. Gas motors aren't really impacted like diesel engines are. Different principle of operation and no visible soot output like a diesel produces and under EPA guidelines the emissions hardware has to remove ALL visible soot and it has to go somewhere because the engines still make it despite the fact you no longer see it.

Has to go somewhere and it does. it's collected in the DPF cannister and incinerated by the use of additional diesel fuel, injected onto the DPF cannister under high heat conditions and it's 'reduced to ash which eventually fills the DPF cannister and must be cleaned or changed out with a cleaned or new element. With a gas motor, unless you have an oil burning issue or an over fueling issue, nothing has to be renewed or replaced because there is no visible particulates produced and the 'noble' metal coated substrate on the cat converts the carbon monoxide to carbon dioxide and water.

The urea injection (DEF) post DPF cannister uses a urea based solution to chemically alter the oxides of nitrogen produced by the engine into carbon dioxide and water.

The issue lies with hardware and software failure, not the actual processes and none of it is cheap to buy or replace either.

Tractor builders have went to common rail ECM controlled injection to minimize the amount of 'pollutants' that enter into the system to be catalyzed' and reduced to acceptable stack emissions. It's all peachy on paper, but in the real world it's not because the components are purchased on a totally cost basis so the cheaper they can be had, the better and because of that, failures are not that rare.

At some point in every T4 final tractors life, the DPF will have to be cleaned or renewed. Probably won't be the first owner unless they use the unit in an ag setting and crank up some serious engine hours, but, at some point with some owner it will have to be done.

Kubota (only one I know about) states 2500 regens before cleaning and that is a lot of meter hours, probably more than 99% of people on here will ever accrue. However, lf internal engine conditions are less than optimal and excessive soot is produced, the regens will be close together and the ECM constantly tracks it so cleaning and/or replacement could very well be on the first owner. Things like a dirty air filter or contaminated engine oil or poor fuel can contribute to excessive visible particulates being produced and more frequent cleaning / replacement.

Why the EPA requires a 5 year emissions warranty on all T4 engines and related emissions components.

Also why T4 interem tractors are in high demand and bring premium prices. That and the fact that none are being produced anymore makes them very valuable\, especially to buyers who don't want to deal with emissions related failures.

I know, I have 2 and they way it's going, soon they will be worth more than what I bought them for new.

I do believe with the current ECM controlled fuel management systems, even though they consume more fuel than their earlier counterparts, the fuel management systems make them as fuel efficient as the older non compliant tractors.

 

[5030]

I look at my Pre 4 tractors as an investment today, more than anything else. The smaller the playing field gets, the more they are worth, especially if taken care of and mine are.

 

[MinnesotaMorg]

Appreciate the detailed responses.

Is there any advantage of DOC vs DPF? either maintenance, cost, downtime etc? You mention the doc will be higher heat in the exhaust all the time, but it seems like the doc doesn't need to be replaced or cleaned like the DPF?

Also is there any easy way to search for T4 interim tractors? I'm assuming there are certain model years that escaped the emissions requirements.

EDIT: I should add I'm specifically staying below the 75hp limit to eliminate DEF. My thought process is the fewer emissions systems, the less stuff that can break increasing my overall cost.

 

[ericm979]

To be more specific, the EPA Tier 4 regulations set emissions limits on a per HP basis, with few emissions per HP as engines get larger. There are breaks at 25.5hp and 75hp, and a couple under 25.5hp that are not important for compact tractors. It's easier to make larger engines pollute less. Manufacturers are free to use whatever technology meets the requirements. Below 25.5hp, engine tuning (combustion chamber shape and injection timing) are enough. Above 75hp the manufacturers use DEF and EGR, which is where a lot of the problems with diesel trucks are.

Manufacturers have had a while to work out the bugs for their emissions systems at this level. The vast majority are reliable. Most CUT emissions system problems are from operator error: excess idling, operating at too low an RPM, delaying regens. Follow the owner's manual and the tractor will have a long operating life and you will breathe fewer toxins.

Under normal circumstances tractor DPFs are designed to go about 3000 hours before needing cleaning. Which is a lot of years at the typical user's one or two hundred hours a year. Currently DPF cleaning prices are in the $400 range.

I was somewhat concerned about the emissions system when I bought a new Branson four years ago. It's not caused any problems at all. With my old '90s tractor, idling while changing implements would quickly stink up the barn. When running a PTO chipper I had to make sure it was a windy day so I wouldn't gag on diesel stench. The new one does not do either of those even though it's twice the hp. Totally worth it in my book.

 

[mo1]

Hi there,

I am new to the tractor game, I am trying to take my time and absorb as much information I can before I pull the trigger on a tractor.

Can someone explain to me why some tractors (MF 4707 / NH Workmaster 75) don't need a DPF and others in the same class (5075e / M4D-071) have a DPF? Everything I can find indicates that DPF is not desirable and will only serve to increase your initial cost and maintenance over time.

The Kubota salesman I talked to said new holland might be using engine credits or something. But would that mean that the consumer is just better off taking advantage of the companies using those credits? Assuming everything else is equal, is it in my best interest to choose a tractor with no DPF?

Thanks for coming to my ted talk
Morgan

All diesel engines in the >25 to <75 HP range have to meet a certain set of EPA emissions regulations, and those include soot (particulate) emissions as well as other things such as nitrogen oxide and hydrocarbon emissions. Long story short, these tractors must have some sort of soot control as well as a dry (non-urea) catalyst. The only currently-used way to control soot is to ultimately burn it off using high exhaust gas temperatures (EGTs.)

CNH's equipment in that size range uses engines that are tuned to keep the EGTs hot enough that the soot produced is (supposed to be) instantly burned off when it comes into contact with the hot catalyst media. Equipment with a diesel particulate filter have this filter in front of the catalyst. These engines are tuned "more normally" and thus the EGTs on these units are generally only hot enough during normal operation to sufficiently heat up the filter to burn off soot if the engine is being run at a decently heavy load for a period of time ("passive regeneration.") If the engine is not being run that hard, the filter eventually fills up with soot and the engine's computer changes parameters to heat up the EGTs temporarily in order to heat up the filter to burn off the soot ("active regeneration.")

The issue with the DOC setup is that if the engine is run for short runtimes or other situations where the DOC remains too cold to burn off soot for a prolonged period of time, the DOC can plug up (face plugging) with no method to clean it off other than to remove the catalyst and professionally clean it. This is similar to what has to be done when the DPF has too much accumulated ash after >3000 hours.

 

[rScotty]

Appreciate the detailed responses.

Is there any advantage of DOC vs DPF? either maintenance, cost, downtime etc? You mention the doc will be higher heat in the exhaust all the time, but it seems like the doc doesn't need to be replaced or cleaned like the DPF?

Also is there any easy way to search for T4 interim tractors? I'm assuming there are certain model years that escaped the emissions requirements.

EDIT: I should add I'm specifically staying below the 75hp limit to eliminate DEF. My thought process is the fewer emissions systems, the less stuff that can break increasing my overall cost.

Let's see.... Interim Tier 4 came in different years for different engine sizes - I believe that the 50 to 100 hp range was about 2007 to 2014. Someone can check me on that but it is easy enough to look up the chart. Remember, the Tier 4 interim did have some emission control systems. For example most had a fairly complex EGR system. And those are not starting to need some attention.
If you want back to before any emissions control at all you may have to step back to pre-Tier 4 interim. The Tier 2 & Tier 3 manchines had almost none or almost no emissions controls.
FOR A CHART, GO TO:

https://dieselnet.com/standards/us/index.php

So it's not all simple.
I have one DEF diesel - I love it. It doesn't have any fumes at all. No super hot exhaust, no soot, and no odor. If I get to choose, my next tractor will certainly have DEF too. All the newer John Deere 310 models have it. It's a very simple system with minimum parts to wear, but does add another fluid which increases the cost - in my case about ten cents a gallon.

The big advantage to DEF isn't something you notice until you have one - and it's a personal advantage that doesn't make a difference to everyone. It is that unlike DOC and DPF which need to be run at high RPM most of the time, the DEF machine can idle along like the old fashioned diesels when it isn't working hard. I'm used to that, and used to the way those old pre Tier IV diesels would idle along until the governor would rev them up to meet a heavy load ... and then automatically go back to a lower RPM when the load isn't there. I like a motor that does that.
It's my land, I grew up with diesels that worked that way, and its relaxing to me.

As a side benefit, I think that an engine worked at variable RPM will last longer - though in fairness that's still a debate and unproven. One thing that isn't debatable is that a machine that automatically idles down sure uses a less fuel. Half the time or more it's just idling. When it does rev up, it rarely goes over about half throttle. Consider that in your overall cost.

When working, I set the throttle for would be called a "fast idle" - about 1200 RPM - and let the governor & auto-throttle take care of the rest. I can always over-ride it with the throttle. But frankly I rarely find a need for full throttle horsepower. So the 60 horse tractor probably runs at about 30 hp most of the time, and the 90 hp not much more. Backing off to half throttle still gets the work done, less expensively, more enjoyably - but you have to have either a pre-tier IV and put up with the smoke, or move up to DEF if you want good idle capability.

Good Luck, rScotty

 

[Hay Dude]

The first few years of DPF machines were nothing more than manufacturers using customers as guinea pigs. Then they made us spend wild sums of money to fix them-mostly out of warranty. Ask me how I know.
Now they seem to have improved in reliability, but some of us have a bad impression of the early versions. The trucks reliability were so bad in the beginning that it knocked CAT and IH out of the OTR diesel truck engine business-probably forever. Even the venerable IH DT-466/530/570 couldnt survive when they became “MAXXFORCE” diesels. IH now uses Cummins. Thats a pretty sad/amazing end to many years in the OTR diesel engine business. They paid a lot of money in lawsuits, too.

The new systems are better, but no diesel with a DEF system could be more reliable than an older diesel without one. Theres more tanks, lines, wires, pumps, electronics and sensors. They will fail once warranty is over and the end user will foot the bill.
More cost of doing business.

 

[mo1]

When working, I set the throttle for would be called a "fast idle" - about 1200 RPM - and let the governor & auto-throttle take care of the rest. I can always over-ride it with the throttle. But frankly I rarely find a need for full throttle horsepower. So the 60 horse tractor probably runs at about 30 hp most of the time, and the 90 hp not much more. Backing off to half throttle still gets the work done, less expensively, more enjoyably - but you have to have either a pre-tier IV and put up with the smoke, or move up to DEF if you want good idle capability.

Good Luck, rScotty

"Fast idle" is actually a technical term, it is the speed the engine runs at full throttle with no load. For a typical 60 HP tractor diesel it is going to be somewhere in the 2200-2700 RPM range depending on the exact engine.

Your engine will only make as much power as is demanded of it, up to the maximum amount of power it can produce at that RPM. If you are just driving around and your tractor needs 5 HP to do this, your engine will only make 5 HP regardless if it's running at 1200 RPM or wide open. The engine does use more fuel to run at full speed making low power compared to running at lower speed, the reason is higher frictional losses with the pistons, crank, valvetrain, etc. moving faster.