Mahindra Tractors-Should You Buy One?

[tradosaurus]

The biggest selling point for me on the mahindra was no dpf. I also like the dealer. My 3650 pst has 350 hours on it now and still no issues.

That's not entirely accurate. They don't have a regen which forces the tractor to burn hot for a period of time to burn the soot off of the collector but MF (and Mahindra) has a mCRD (DOC system) system which runs hotter all the time to burn off the soot. This is not new technology and is really is dishonest for a tractor mfg to tout this as a benefit over DPF.

DOC is a catalytic converter. The exhaust gas passes through a material which oxidizes/breaks down the environmentally "harmful" stuff. "The diesel oxidation catalyst is designed to oxidize carbon monoxide, gas phase hydrocarbons, and the SOF fraction of diesel particulate matter to CO2 and H2O"

A DPF is a more extensive breakdown system. It usually has a DOC, then a DPF. Some systems also use Diesel Exhaust Fluid (DEF), in addition, which is yet another addition, spraying that fluid the exhaust to further break down the "harmful" particles.
" Exhaust gas passes through the DOC and then into the DPF where Pariculate Matter is collected on the walls of the DPF. The PM collected is then oxidized to remove it from the DPF. This is known as regeneration. When operating conditions maintain sufficient exhaust temperatures, the DPF is continually self-regenerating. This is known as passive regeneration and results in clean exhaust out of the tailpipe. On very infrequent occasions, an active self-regeneration is required to remove a build-up of PM in the DPF, due to insufficient exhaust temperatures. Exhaust temperatures are raised by injecting a small amount of fuel upstream; The resulting chemical reaction over the DOC raises exhaust gas temperatures high enough to oxidize the PM from the filter."

 

[npalen]

I bought a Mahindra 3015 (30HP) four or five years ago at a good price. Put a Westendorf loader on it with the intent of reselling to make a little profit. It's probably worth quite a bit more today but I can't bring myself to let it go. It is an amazing tractor but then so is my little Kubota B9200!

 

[Deleted member 371759]

That's not entirely accurate. They don't have a regen which forces the tractor to burn hot for a period of time to burn the soot off of the collector but MF (and Mahindra) has a mCRD (DOC system) system which runs hotter all the time to burn off the soot. This is not new technology and is really is dishonest for a tractor mfg to tout this as a benefit over DPF.

IMO DOC is a 100% benefit over DPF. No fluid, no sensors and totally maintenance free, also plenty of solutions after the 10's of thousand of hours it will last. Unlike DPF which requires custom tuning to remove. Most diesels run a DOC pre DPF to protect the DPF and to help light it off. There is a reason pre-emission diesels are heavily sought over their emissioned to death counterparts. The whole runs hotter thing is not true. There is no raw fuel injected into the DOC unlike DPF which needs the fuel to reach temps high enough to burn the soot to ash. All that's heating the DOC is exhaust. You are correct that its not new technology and IMO again that is a huge benefit new does not mean good by any means. Also DOC efficiency does increase with heat until a point, at around 400c-750F its efficiency starts to decline. DOC requires a temp of around 200C to light off, so EGTs of 200C are pretty low. Even in your post you noted that pre DPF there is normally a DOC. How would a DOC only engine run hotter than a engine with a DOC pre DPF?

 

[tradosaurus]

IMO DOC is a 100% benefit over DPF. No fluid, no sensors and totally maintenance free, also plenty of solutions after the 10's of thousand of hours it will last. Unlike DPF which requires custom tuning to remove. Most diesels run a DOC pre DPF to protect the DPF and to help light it off. There is a reason pre-emission diesels are heavily sought over their emission to death counterparts. The whole runs hotter thing is not true. There is no raw fuel injected into the DOC unlike DPF which needs the fuel to reach temps high enough to burn the soot to ash. All that's heating the DOC is exhaust. You are correct that its not new technology and IMO again that is a huge benefit new does not mean good by any means. Also DOC efficiency does increase with heat until a point, at around 400c-750F its efficiency starts to decline. DOC requires a temp of around 200C to light off, so EGTs of 200C are pretty low. Even in your post you noted that pre DPF there is normally a DOC. How would a DOC only engine run hotter than a engine with a DOC pre DPF?

There's a reason why during regen process the heat is increased.

According to Neil Messick who compared a L3301 to a Mahindra 1533 he explains that the only difference between the mCRD and DPF is that DPF has a soot capturing mechanism and once enough soot is captured it goes through a burn cycle (hotter temperature) to burn off the soot. This typically happens between 20-30 hrs on average.
A DOC system (mCRD) doesn't have that screen or filter capturing mechanism but it still needs to produce clean exhaust. The way that Mahindra achieves this is that it is ALWAYS in a burn cycle. The way that it happens is that the exhaust stream has to be abnormally hot which is accomplished through tuning the engine to burn hotter.

Most owners will never own their tractor long enough to worry about replacing a DPF.

I believe Kubota and Deere would be using the mCRD "technology" if they thought it would be more beneficial.

https://youtu.be/GOcaeqmNGco

 

[Deleted member 371759]

There's a reason why during regen process the heat is increased.

According to Neil Messick who compared a L3301 to a Mahindra 1533 he explains that the only difference between the mCRD and DPF is that DPF has a soot capturing mechanism and once enough soot is captured it goes through a burn cycle (hotter temperature) to burn off the soot. This typically happens between 20-30 hrs on average.
A DOC system (mCRD) doesn't have that screen or filter capturing mechanism but it still needs to produce clean exhaust. The way that Mahindra achieves this is that it is ALWAYS in a burn cycle. The way that it happens is that the exhaust stream has to be abnormally hot which is accomplished through tuning the engine to burn hotter.

Most owners will never own their tractor long enough to worry about replacing a DPF.

I believe Kubota and Deere would be using the mCRD "technology" if they thought it would be more beneficial.

I was going to add to the end of my post. "Quit listening to neil messick". Hes not a diesel mechanic, hes a Kubota salesman. I knew this was where the info came from. I have no idea why Kubota or Deere does not use DOC. I can think of several reason and its all speculation on my end. I know DPF and its use created an whole industry around it. Replacement filters, DPF cleaning "technology, "DPF liquids, I can bet Deere and Kubota pay pennies for what is a several thousand dollar upcharge to the end consumer. DOC technology has been around for a long time and its known that excess heat diminishes its emissions reducing capacity. mCRD does not inject raw fuel to the DOC. DOC only uses normal diesel exhaust to keep its temps. Like I said DOC begins working at 200c and starts to lose its capacity to scrub emissions at around 450C which is why DPF was created in the first place as EGTs rise into the 600,700,800,900 range DOC becomes less efficient and then relies on the DPF to capture what is missed by the DOC. The engine is not tuned to burn hotter, low to normal EGT temps fall in the range of the DOCs most efficient working range. No reason a company would burn a DOC hot when it would just make passing its emissions standard harder.

 

[tradosaurus]

I was going to add to the end of my post. "Quit listening to neil messick". Hes not a diesel mechanic, hes a Kubota salesman. I knew this was where the info came from. I have no idea why Kubota or Deere does not use DOC. I can think of several reason and its all speculation on my end. I know DPF and its use created an whole industry around it. Replacement filters, DPF cleaning "technology, "DPF liquids, I can bet Deere and Kubota pay pennies for what is a several thousand dollar upcharge to the end consumer. DOC technology has been around for a long time and its known that excess heat diminishes its emissions reducing capacity. mCRD does not inject raw fuel to the DOC. DOC only uses normal diesel exhaust to keep its temps. Like I said DOC begins working at 200c and starts to lose its capacity to scrub emissions at around 450C which is why DPF was created in the first place as EGTs rise into the 600,700,800,900 range DOC becomes less efficient and then relies on the DPF to capture what is missed by the DOC. The engine is not tuned to burn hotter, low to normal EGT temps fall in the range of the DOCs most efficient working range. No reason a company would burn a DOC hot when it would just make passing its emissions standard harder.

So why would Kubota and Deere install a DPF if it could satisfy Tier IV emissions without it? Why does my 6.7L F250 have a DPF if it could magically have clean exhaust without one?

 

[Deleted member 371759]

So why would Kubota and Deere install a DPF if it could satisfy Tier IV emissions without it? Why does my 6.7L F250 have a DPF if it could magically have clean exhaust without one?

They could obviously have meet tier IV emissions without a DPF because other companies have. So that would be a good question for Deere and Kubota.

 

[tradosaurus]

They could obviously have meet tier IV emissions without a DPF because other companies have. So that would be a good question for Deere and Kubota.

Not buying your explanation of how Mahindra's mCRD works.

 

[Deleted member 371759]

Not buying your explanation of how Mahindra's mCRD works.

Thats not how mCRD works. Its how a DOC works. mCRD I'm sure involves a ton of other things. Im sure everything was reworked I know its common rail injection with a pretty high PSI fuel delivery up to 23,000 PSI I read somewhere. I'm willing to bet Mahindra rolled the dice on passing emissions standards to sell enough tractors to people that did not want complicated emissions systems for a long enough time to make money. These tractors will not pass a more strict emission standard and they will have to go back to the drawing board. But I dont care I have a tractor without DPF, SRC and I will keep it as long as I can. I drive a 6.6 Duramax LB7 with no emissions and a OBS 7.3 Powerstroke with no emissions.

 

[Mancelona Man]

So far I have about 40 hours on my 2638 and it’s been a good tractor.