John Deere 770 help!

[Dmpalinkas]

Hello- I just bought a JD 770 to maintain a gravel driveway and plow snow, etc...and unfortunately cannot find much information on it. I was told that it is an '89, but looked up the model #/serial on the JD website to confirm and cannot find a match. Also- I absolutely cannot find any good, reliable information on the engine.

I'm 100% sure it's a Yanmar, but the person I bought it from said that it was the upgraded engine that was 30 hp, but again- I can't find (reliable,consistent) information on this engine model # on any Yanmar and/or JD website.

Does anyone know any resources that I haven't found yet?

Serial #on the engine... *CH3045D001835* Model 3TN82 - RJK

thanks for any help!

 

[joecdeere]

that's the engine model and serial number

the tractor plate is on the rear bottom of the unit right where the PTO shaft comes out.

should look like the following -

1989 MODEL (SERIAL NUMBER M00770A001001-010000)
1990 MODEL (SERIAL NUMBER M00770A010001-105926)
1991 MODEL (SERIAL NUMBER M00770A105927-116950)
1992 MODEL (SERIAL NUMBER M00770A116951-120000)
1993 MODEL (SERIAL NUMBER M00770A120001-130000)
1994 MODEL (SERIAL NUMBER M00770A130001-140000)
1995 MODEL (SERIAL NUMBER M00770A140001-150000)
1996 MODEL (SERIAL NUMBER M00770A150001- )

 

[kebo]

Below is the tractordata link for the JD 770:

TractorData.com John Deere 770 tractor information

Here is the engine information:

Yanmar 3TN82-RJX
diesel
3-cylinder
liquid-cooled
83.1 ci [1.4 L]

According to that website, the engine has 23hp, and the PTO is 20hp. If it was upgraded, there's no telling how it was done!! Bigger block????

 

[Tractor Pilot]

Dmpalinkas,

John Deere 770 Compact Utility Tractor Service Manual
John Deere 770 Compact Utility Tractor Service Manual Technical Manual TM1470 PDF Download

Bruce

 

[Dmpalinkas]

It's definitely not the RJX engine. Within that class (3TN82), there are quite a few variations. I'm still having trouble finding an answer. Some say it's 30hp, some 24, some 25. Strange that I can't look it up on the Deere or Yanmar site.

 

[Dmpalinkas]

Somebody told me that they "play" with the stroke on the pistons to increase displacement (and power).

 

[Tractor Pilot]

Have you tried calling or stopping by your local JD dealer?

My 1997 JD770's stock 24hp Yanmar engine model # is 3TN82-RJK. The JD generic Service Manual says 3TN82-RJX. I assume the "X" is a variable. I have never heard of a stock 3TN82-RJK engine ever producing 30hp. Various JD manuals state either 23 or 24HP.

My engine's serial # is CH3045D017033. Looks like your engine is older than mine.

If you look up your "Product Serial Number" on the plate above your rear PTO - tractordata.com will tell you the exact year the tractor was manufactured. If it's a 1989 tractor, your low engine serial # looks about right for that year. So the question is: Is your engine stock or rebuilt? JD may have an answer if they did the work. If it was some 3rd party, you may never know for sure if the paperwork was lost.

 

[Dmpalinkas]

Thanks- I'd like to put on new tires. The tractor came with the factory size turfs, but I want to put on a "real" tractor tire. I probably won't ever need to drive on the grass. If I do, it will be sporadic. I do understand that I'll have to buy entirely new rims as well. What is the biggest size I can put on this tractor? They're loaded with calcium now- I have a ballast box, so I probably won't do that again. Thanks for any help or insights.

 

[mark blackburn]

Does anyone know where I can find front 4x4 gears for 770 jd 98 model other than a dealer?

 

[zzvyb6]

A 30 hp motor available on the 870 had 4 cylinders. 1070's 36 pto hp is 4 cylinders. 770 etc. had 3 cylinders. Bore and stroke and compression are the power variables.

 

[beenthere]

:welcome: to TBN

Are you looking for used, so not interested in trying to buy new from Deere?

Not exactly sure what you mean by "4x4 gears" and it may be confusing to others just exactly what is happening, or has happened. What more can you tell us?

 

[RoyJackson]

The 770 had a 24 gross HP engine, 20 at the PTO. IF there is a 30 HP engine in there, it's probably out of a first generation 790, which had 30 advertised HP. My opinion is the seller embellished the HP rating. Putting it bluntly, he bullsh*tted you.

I suspect the 4x4 gears Mark Blackburn is asking about is the front axle spur gears. Those gears do well going forward, but backing with a load has resulted in breakage. The 770 and 790 used the same axle (for the 790's first generation, at least)...best place to look is a tractor salvage yard. Wenger's (Wengers Of Myerstown - Farm Equipment, Agriculture Equipment, Tractor Parts, Construction Equipment, Construction Parts) would be one place I'd call...

 

[Industrial Toys]

I can't imagine that there is a diesel engine on the planet that is an upgrade to a Yanmar! Unless maybe the upgrade was to furnish more horses.

That whole tractor is a Yanmar and when I met the JD territory manager or something like that, around the mid ninties, he said they simply reffered to that tractor as the Yanmar