Engine changes to Diesel x7xx series.

[JDTank]

I just noticed, for 2011 onward, the diesel engines in the x7xx series garden tractors are now smaller.

2006-2010 power-plant:

YANMAR | 3TNV76-CSA

2011 - current power-plant

YANMAR | 3TNM72


I am on the verge of ordering my new X740, probably in the next month or so, and I am wondering if anyone who has a 2011 or 2012 machine has noticed the drop in HP and torque? Given that this is such a small engine, the loss in 1 and a half ponies shouldn't even be noticeable, but then again, it never hurts to ask.

I noticed in the new engine, the stroke is shorter, AND the bore is smaller. The max RPM is now 3600, vs the older engines 3200 RPM.

Horsepower Ratings:

2006 - 2010 = 25.1 HP
2011 - current = 23.6 HP

Torque Ratings:

2006 - 2010 = 49.1 ft pounds at 2,300 RPM
2011 - current = 40.9 ft pounds at 2,600 RPM

Also, the new engine is a whopping 74 pounds lighter! They dropped a 243 pound engine, down to 169 pounds....that is a HUGE weight savings, and it scares me to death that they sacrificed strength for weight savings.

Some other significant differences:

- New engine has electric fuel pump, old engine had a mechanical fuel pump.
- New engine has a 20 amp alternator, old engine had a 40 amp alternator.
- New engine has a 5 blade, 290MM cooling fan, old engine had a 7 blade, 335MM cooling fan
- New engine holds more oil then the old engine, numbers are conflicting between the brochures and tractordata.com information
- New engine dimensions - Length: 17.7 in, Width: 15.7 in, Height: 19.8 in
- Old engine dimensions - Length: 22.4 in, Width: 16.9 in, Height: 22.6 in
- New engine is part of a Yanmar series called MINIMAX

The reduction in physical size is quite impressive, not only in weight, but look at the differences in the dimensions, almost 5 inches shorter then the older engine.

Looking at the brochure, it looks as if this new engine is substantially quieter, and half of the engine is a new, better design, with better valves and less chatter as well. Who knows, maybe with it being a bit smaller, it will be even better on fuel then the old ones, and they were impressive on fuel consumption themselves.

So, does anyone have any experience with the new, smaller Yanmar diesel?

 

[Deere Dude]

I have a 2009 and was going to get a new one and trade in the old one but I may hold on to it for the time being until I read more about this. I know mine has a lot more power than the 2005 or 2006 model I had previously. I thought they would all have the same HP and torque, but I guess not.
I am going to follow this post for a bit.

 

[Bigkrank]

They are both indirect injected engines.

This will probably not apply in your situation or use but something to think about anyways. The similar direct-injected 3TNE78 engines are used in tractor pulling. They are rather weak in the cylinder area compared to a Kubota or Shibaura. Guys are splitting them apart between 1 & 2 cylinders. They have to pour the blocks and run them dry to stabilize the cylinders.

Myself I would be a bit leary of using a lighter yet version of this engine but as I said maybe in a bone stock situation there may be nothing to be concerned about.

 

[JDTank]

They are both indirect injected engines.

This will probably not apply in your situation or use but something to think about anyways. The similar direct-injected 3TNE78 engines are used in tractor pulling. They are rather weak in the cylinder area compared to a Kubota or Shibaura. Guys are splitting them apart between 1 & 2 cylinders. They have to pour the blocks and run them dry to stabilize the cylinders.

Myself I would be a bit leary of using a lighter yet version of this engine but as I said maybe in a bone stock situation there may be nothing to be concerned about.

In all honesty, I wouldn't expect ANY engine of this size to last when your in pulling competitions. These are lawn mower engines, not class 8 highway diesels.

I appreciate the information nonetheless. I am more concerned with leaving the machine bone stock and getting 5,000 hours out of it.

 

[Bigkrank]

I would be more worried about needin a new butt if your going to sit on that thing for 5000 hours

 

[JDTank]

I would be more worried about needin a new butt if your going to sit on that thing for 5000 hours

In 30 or 40 years, I will need a new butt regardless :laughing:

 

[Gonerafting]

Save your butt, just changed over to the Deluxe Seat (Air Seat), well worth it! PS: I have a 2010 and do not know if the changes really matter, the heavier weight of my motor just means less weights if I decide to pull implements and for snow plowing putting more weights on the back. In my case, heavier is better. All things continue to improve, I would not be concerned about the engine change. I would be looking at model differences, I sure wish I could have justified an X749! As far as the alternator differences, I thought all the diesel came with the 40amp or is it now an option?

 

[psdx]

The displacement is 25% less and the torque drop is roughly 20%, and the peak is now at a higher rpm. I can't imagine you could help but notice that difference when cutting tall grass. The general direction over the past 30 years or so has been smaller displacement and spinning the motor faster. I can remember tractors running at 2100 rpms for the 540 PTO output. This is just another step in that progression. I'm guessing this large of a step must be related to emissions?

 

[murphy1244]

2006 - 2010 = 49.1 ft pounds at 2,300 RPM
2011 - current = 40.9 ft pounds at 2,600 RPM

That would be the most concern for me

 

[JDTank]

Obviously it had something to do with meeting emissions requirements, but I honestly didn't think they would have gotten that drastic with it.

What I am very curious about is why the loss of 74 pounds. They dumped more then a quarter of the engines weight, in one redesign. What was that weight before, and where has it all gone? Being that the bore and stroke are smaller, it decreases everything. Smaller pistons/connecting rods in smaller cylinders, in a smaller engine block, with a smaller head. I guess I can see how losing a little bit of metal on a lot of parts could add up to 74 pounds.

 

[JDTank]

2006 - 2010 = 49.1 ft pounds at 2,300 RPM
2011 - current = 40.9 ft pounds at 2,600 RPM

That would be the most concern for me

Kubota's diesel riding mower is only a 21HP machine and makes less torque then the new Yanmar diesel, so the new Yanmar must still be able to make some good power.

 

[Bigkrank]

Not sure I like this line:

Rated output at 3600 rpm (intermittent): 23.6hp

in this spec sheet:

Diesel Progress Online | MINIMAX : Yanmar America Corp.

Couldn't find what engine speed is for pto speed on JD site? I think this engine in a Cub is 3300 @ PTO speed.

 

[JDTank]

Not sure I like this line:

Rated output at 3600 rpm (intermittent): 23.6hp

in this spec sheet:

Diesel Progress Online | MINIMAX : Yanmar America Corp.

Couldn't find what engine speed is for pto speed on JD site? I think this engine in a Cub is 3300 @ PTO speed.

Could have something to do with Yanmar covering there behind. Engine manufacturers have gotten more and more sticky with there fine print. Ever since emissions laws became stricter, it's becoming increasingly difficult to get good performance out of an engine that has emissions controls on it.

 

[willi67]

I was doing the same research not so long ago.
The change in engine and hydraulic drive took me by surprise, don't like to be the first to try new stuff. Even looked for a used 2010 X748 but did not find one in time. Dunno if you follow this
http://www.mytractorforum.com/showthread.php?t=156907
hope its ok to post links since it was done in another X700 thread.
The new motor should still be plenty as I think its used in the 1023E and the Yanmar 2400. The old 3TNV76 is in the 1026R?
The 2010 X748 was a little beast at 1.1 litres .. my BX2360 is only 0.9 so now they are equal

 

[Bigkrank]

Got to looking and forgot how small those tractors are. We got several damaged hoods off dealers for some of our builds. That new engine should be plenty for it.

 

[Captain Ned]

I look at it this way:

I've been lurking here to decide if I want to drop the long green (heh) on an X748 or X749. Despite the reduction in the size of the Yanmar motor I've got to believe that even the smaller unit will so far outlast the overheated, undercooled, oil-leaking mess of a Kohler in my Cub GT2544 that the four-fold price difference will be repaid in time and then some.

 

[JDTank]

I look at it this way:

I've been lurking here to decide if I want to drop the long green (heh) on an X748 or X749. Despite the reduction in the size of the Yanmar motor I've got to believe that even the smaller unit will so far outlast the overheated, undercooled, oil-leaking mess of a Kohler in my Cub GT2544 that the four-fold price difference will be repaid in time and then some.

Either machine you go with you will be satisfied completely. You will save big money in fuel, maintenance, and lack of repairs needed. With the diesel X7xx series tractors, you can basically change the oil, and add diesel, and go on like that for years at a time.

I have never had any experience with Kohler engines, but I haven't heard the best things about them. I seen one torn down at a local lawn mower parts shop about 3 months back, and I was pretty unimpressed with it's condition for the low hours it had.

 

[jcmseven]

I should also mention, and hopefully someone with more recall than I have can chime in, that new power equipment engines are being judged now by a stricter SAE standard, and all the power readings went down to better approximate the TRUE power of the engine in its said application. If the new Yanmar is being judged by this new stricter standard, it would seem that perhaps it is making more power than did the previous one in place. 23.6 HP, if under the new standard would be likely equivalent to 25-26 in the old standard. Also, I would have to express my reservation on the torque numbers on the X series small (24 HP diesels). I do not recall that they are rated with 49 lb/ft of torque. The 1 L Yanmar (also the same engine as my 2320 has) is rated at roughly 41 ft/lb torque. I have seen rated speed ranges from 39.6-41.7 ft. lb. on that engine but nothing up close to 50 (though I think it is possible the engine has that much). That higher number would put this engine really close in torque to the direct injected Yanmar in the 2520 with about 52. It looks like the new engine is making about 41 lb/ft, which would be right in the ballpark of the torque numbers I have seen from the previous engine. So assuming all this is true, that the HP/Tq are as good, or better with this engine and the engine has so many important upgrades, it likely would be a great choice. I would rely on someone with more up top than I have to verify or refute the numbers I had in my head.

John M

 

[JDTank]

I should also mention, and hopefully someone with more recall than I have can chime in, that new power equipment engines are being judged now by a stricter SAE standard, and all the power readings went down to better approximate the TRUE power of the engine in its said application. If the new Yanmar is being judged by this new stricter standard, it would seem that perhaps it is making more power than did the previous one in place. 23.6 HP, if under the new standard would be likely equivalent to 25-26 in the old standard. Also, I would have to express my reservation on the torque numbers on the X series small (24 HP diesels). I do not recall that they are rated with 49 lb/ft of torque. The 1 L Yanmar (also the same engine as my 2320 has) is rated at roughly 41 ft/lb torque. I have seen rated speed ranges from 39.6-41.7 ft. lb. on that engine but nothing up close to 50 (though I think it is possible the engine has that much). That higher number would put this engine really close in torque to the direct injected Yanmar in the 2520 with about 52. It looks like the new engine is making about 41 lb/ft, which would be right in the ballpark of the torque numbers I have seen from the previous engine. So assuming all this is true, that the HP/Tq are as good, or better with this engine and the engine has so many important upgrades, it likely would be a great choice. I would rely on someone with more up top than I have to verify or refute the numbers I had in my head.

John M

To be honest, I am surprised they have not moved to direct injection with the diesels in the X7xx series. I thought for sure when this new engine came out for the 2011 model year it would have been direct injected.

Personally, I feel good about this new engine. I don't believe John Deere would continue to use Yanmar diesels in the X7xx series unless they could continue on with the reputation of that series. These machines are the top of line in there size and class, for John Deere to throw a unworthy engine under the hood would make no sense at all. Of course diehard fans would continue to buy no matter what even if they did use junk, but it would only be a matter of months before owners would rack up hours and tell the world of all there troubles.

The biggest choice I have now is between the X540 and the X748. Don't you hate that when your wallet decides things for you? At the same time, you only live once, so you feel like telling your wallet to shut up.

 

[jcmseven]

I agree with you. There is a big price difference between those two machines. I think the engine JD puts in the Premium tractor will be fine. As you know JD is very particular about its engines and it will stand behind the product. I have never known Yanmar to make a bad engine. Over the years, I have had several of them in various pieces of JD equipment and have seen some incredible hour logs of machines powered by Yanmar. My perception is that this new engine is as powerful if not more powerful in reality than its predecessor. It likely is also cleaner running and more quiet. I bet it will also be better on fuel. If you can stomach the upfront cost of the 748, you will love the machine. If you go to sell it, unless it is in poor condition you should get a more significant portion of the original value out of the machine. My best analogy is the 455, a similarly sized machine that the X series replaced. When they come in on trade, my dealer, who is a large dealer, says they disappear at a rate of 3:1 v. the equivalent 445 gas powered machine.

John M