955 motor in 855

[WIJohnDeere855]

Has anyone tried putting a JD 955 motor in a JD 855?

 

[beenthere]

Must be more to the story behind the question. :confused3:

 

[WIJohnDeere855]

My 855 I just bought is showing signs of low compression. It is going to the JD dealer to have them test if its rings or cylinder issues. Anyway I found a 955 being parted out and didnt know since the frames or the 855 and 955 are nearly the same if the motors would be a match.

 

[RoyJackson]

I can't help you with the fitting question, but that would be a very nice increase in power if the engine does fit.
There's enough similarity between the 855 and 955 to justify buying the 955 as a parts machine.

 

[dfkrug]

Anyway I found a 955 being parted out and didnt know since the frames or the 855 and 955 are nearly the same if the motors would be a match.

Nearly the same? The quick way to check to see if the frames are indeed
the same is check your 855 parts book and compare the frame part #
to the one for the 955. Since you prob do not have the book for the
955, use JDparts.com.

I suspect the engine will fit right it, but I have not done it. 33hp in
a 1970 lb tractor is awesome.

 

[WIJohnDeere855]

I know it a little more power then I need but to pull the old motor have the block redone buy oversized pistons, gaskets then put it all back together I am looking at $2,500-$3,000 if it all goes perfect. I dont have much into the 855 and I can get the motor form the 955 for about $2,000 and I know it has 800 documented and maintained hours, so it just getting broke in. I will post my findings.

 

[dsmau]

Try to get the hydraulic pump off that 955 as well. You will enjoy having more GPM if you use a loader or backhoe. That and the front axle are the 2 differences I know of besides the engine on a recent 855 when compared to a 955. You can also increase the hydraulic relief from 2050 to 2500psi to match the 955. I did it and it is on a thread here on TBN.

 

[Mechanos]

Having an 855 as a parts tractor for my 955, here is a list of the parts that are different that know of....

Transaxle (case is the same but internals are different, different gear ratios on ring and pinion, different low range gear ratios, more steels and frictions in the PTO clutch and PTO brake, etc.)

PTO delay relief valve (different springs for different operating pressures)

Rear final drives (955 has beefier planetaries and longer axle shafts)

Impelement pump

Entire front axle is different

Front and rear tire size

Front wheels are 6 lug on 955, 5 lug on 855

If the 855 is an early model with the fuel tank in front of the radiator, then there are even more differences. Fuel tank, radiator, radiator support, hood hinge rods, etc.

I don't see why the 955 engine wouldn't fit in the 855. I have a 3TNE88 (37hp) in my 955 instead of the 3TN84. It looks right at home there.

 

[dfkrug]

I know it a little more power then I need but to pull the old motor have the block redone buy oversized pistons, gaskets then put it all back together I am looking at $2,500-$3,000 if it all goes perfect.

I have bought the 0.5mm oversize pistons, but you can also get 0.25mm
O/S, and they will cost about $120 per hole for the piston/ring set. If
everything else is OK, you only need to buy a head gasket and pay for
boring service. I don't know who would rebuild it, but it is very straight
forward as engines go, and it sits on top of the frame for easy removal.
Of course, if this a 5000hr engine, you will want to do the head and
bearings.

$2000 for a used 955 engine is no steal, but it will make a better tractor, esp
if you also get the 2500psi pump as DSMAU suggests.

 

[WIJohnDeere855]

Very good info. I did notice the fuel pump needed to be used but never thought of the Hyro pump being able to be changed to 2500psi.

dfkrug: Where did you get the oversized pistions and rings? Are they JD parts? Do you have a part numbers? I found a shop that does Diesel engine machining so that might be a cheaper option. The $2,500-$3,000 came from the JD dealer. I haved worked on motors before so I might look at that option as well since this is a winter project.

 

[dfkrug]

Where did you get the oversized pistions and rings? Are they JD parts? Do you have a part numbers? I found a shop that does Diesel engine machining so that might be a cheaper option. The $2,500-$3,000 came from the JD dealer. I haved worked on motors before so I might look at that option as well since this is a winter project.

All my parts came from JD. Shop around for your best JD dealer for parts.
JDParts.com is supposed to quote you prices for the dealer you register
with. The last 955 I did was years ago, but pistons for the latest JD
I recently finished were about the same price.

Even tho a dealer may quote you for the engine rebuild, they probably
sub it out to a machine shop/engine builder. That means you could take
your engine there directly, or better yet, DIY. All you HAVE to pay for
is parts, boring, and block cleaning.


From the parts book:

AM877970 PISTON RING KIT 3 .25MM (.010") OS
AM878245 PISTON RING KIT 3 .50MM (.020") OS

Note that if you buy bare pistons and rings separately, it will cost MUCH
more.

 

[Brimstone10x]

You could just hone the cylinders and throw new std pistons and rings in it if the bores are not to bad. You would still have to remove the engine but could leave the crank cam injection pump ect in place. I know I know its not the 100% correct way to do it but it would most likely run like new for a few years for very little expence if you do it your self. The 955 engine would most likely be a lot of headachs to make work and still end up with a mutt. just my two cents.

 

[WIJohnDeere855]

Thanks everyone. It sounds like the route I am going is to bore it and put new 0.25 pistons and rings in it. I really want to keep the original motor in it.

 

[WIJohnDeere855]

Any suggestion on what JD book (ie. JD shop manual or Yanmar engine book or ??)covers specs and tearing down the motor to rebuild it? Google searched it but most books wont tell how specific they get.

 

[dsmau]

The deere book for this engine is CTM3

 

[dfkrug]

Any suggestion on what JD book (ie. JD shop manual or Yanmar engine book or ??)covers specs and tearing down the motor to rebuild it? Google searched it but most books wont tell how specific they get.

This IS an issue. The JD tech manual (TM1360) is in no way complete.
There are other manuals that it makes reference to, including the engine
manual that DSMAU quotes. I have the TM and parts PDFs, but not the
CTM3. When I bought my first 955, I also bought an I&T manual on the
7/8/955, but it dealt with very little except the engine. It was a good
manual for the engine rebuild, and I got it for only $15 or so (Overstock.com).
There are several on eBay for $25-30. I really needed that book since the
first 955 I bought came disassembled, with the engine parts thrown in a
box.

 

[Mechanos]

All I'm gonna say is Google it.... never know what you just might find on the internet.

 

[dsmau]

All I'm gonna say is Google it.... never know what you just might find on the internet.

Got it! Like this for instance ? :thumbsup:
CTM3 deere filetype=pdf - Google Search

 

[WIJohnDeere855]

Thanks again everyone for the help. I learn something new everyday. What did we do before the internet!?!?!?

 

[WIJohnDeere855]

Found a local engine rebuiilder that specializes in Diesels and will be doing the boring and going thru the valves for me.