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MM diesel reputation?

J

Josh in MI

Member
Before I take the plunge to get my injection pump rebuilt for my M5, I would like to know how these engines (the 336's) are? The good, the bad....

It seems that a lot of people just dont like them. I know that MM was known for a great LP engine, and I see a lot more gassers than diesels in the smaller machines, especially the U-302 and jetstars. Were the small ones not so desirable?

I remember the M5 diesel as being a very good runner, but kind of a bear to start compared to, say, our 4010. Maybe the pump was on its way out, or maybe they just simply don't start so great. We have a Case 830 diesel that runs great but needs a little encouragement just like the MM.

I guess my question is why are the small MM diesels less popular?
 
Not many 206 diesels were built. This is the basic size for the 445, Jet star, etc. In my opinion, the larger diesel engines are better. I have a UB, M5 and super M670 on diesel. We also have a few g1000 diesels. In cool weather, I use a little either to start the M5.. Afterward it runs really smooth. I definitely prefer MM diesels over lp or gas.
 
MM took their very good gas engine and by using the Lanova combustion system design was able to make a diesel version. The Lanova system has lower peak cylinder presssures which allows lighter components. Both fuel consumption, smoke and unaided startability is worse with this design. Also adding a turbocharger for more power is difficult. The few OEM's that had used this concept abandoned it much earlier than MM which did finally introduce direct injection on the 585. Great way to dieselize an engine in the mid 50's, just not competitive in the 60's.
 
Not really. The valve arrangement is different between the two as far as intake and exhaust valve order from front to back. Plus I am not sure if the head bolt pattern is the same. If they would bolt on you would most likely have to use the 585 manifolds and cam.
 
Although I prefer an LPG MM over anything else, both of our 670 diesels with the 336 cubic inch in them are great tractors with power , and when it gets cold you do either have to plug them in or give them a shot of either but they always start real fast.
 
Good explanation James. Ive never had an MM diesel. The tractors I buy usually need repair and I can afford to tinker/overhaul the gas ones a little cheaper although I would love to have a big G series, (G900 on up). I think they are a very good motor if they are taken care of, as anything is. We used to have a Case 830 diesel which needed help when it got colder. A guy had told me the Case tractors, like the 830s, had the injection pump set for power, not starting. If they were set for easy starting they lost power. Same guy, who has Case tractors said his 830 would need either if you walked by it with an ice cream cone in the middle of summer. (hope its not a double dip lol).
 
I had an M5 diesel, and I would have another one. But they're a hard cold start. When I started mine in the barn in winter I fully expected the local fire department to show up. I could only imagine being a dealer when a fellow showed up to buy one. What a challenge it must have been to sell one. If they started and smoked like mine did, I can't imagine anyone buying one. Maybe on the 4th of July when it's good and hot. Once warmed up I had no complaints at all. The 504's I have start hard and carry on, too. Oddly, the 451 in my 900 starts fast, easy and does not smoke like a chimney.
 
Hey Solid Junk, do you know where I could get a set of O.S. pistons for my 585. I'm at STD now but it's worn to the point that it needs a rebore. I wouldn't mind a decent used set to keep the cost down. Thanks
Bruce
 
Someone passed a cold starting hint on to me. Try "Total Seal" piston rings. I've got a set to put in my my G1000 Vista Diesel. It's bored .125 over! I've not got it together yet but I'm sure the advise is good... it makes sense to get the very top end compression. Oh, and those oversized pistons are "Ross" custom forged! Not cheap but avail. FYI oversized rebuild kits are available through typical avenues (AGCO or Hy-Capacity).
 
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