Common maintenance items on D850 and B7100s?

iangoround · May 16, 2019

Hi All,

I'm new to orange tractors, and diesels in general. Most of my wrenching experience is on race cars and old red iron.

I've just picked up a late model B7100, and the D750 in it has a nasty rod knock. Since it's racecar season I figured I'd never get any machine shop to squeeze me in until the fall, so I sourced a used D850 and it's being delivered to me here on Monday.

I've ordered a full gasket kit for it, but my question is this: Besides replacing any obviously bad gaskets, replacing fluids, greasing fittings, etc, are there any other common problem areas or things I should check while I'm putting this thing back together?

North Idaho Wolfman · May 16, 2019

iangoround said:
Hi All,

I'm new to orange tractors, and diesels in general. Most of my wrenching experience is on race cars and old red iron.

I've just picked up a late model B7100, and the D750 in it has a nasty rod knock. Since it's racecar season I figured I'd never get any machine shop to squeeze me in until the fall, so I sourced a used D850 and it's being delivered to me here on Monday.

I've ordered a full gasket kit for it, but my question is this: Besides replacing any obviously bad gaskets, replacing fluids, greasing fittings, etc, are there any other common problem areas or things I should check while I'm putting this thing back together?

Depending on which D850 you have gotten, Thermosiphon or water pump, it will take different things.

Thermosiphon:
You'll probably just have to swap the oil pan and pickup tube, intake, exhaust, and fan assembly.

Waterpump:
Oil pan and pickup tube, intake, exhaust, add fan, add (if not already equipped) alternator or dynamo, you need to rework the inlet and outlet of the radiator as the angle and the size are different.

If you don't want the task of reworking things, you could simply swap the gear case cover from the D750 to the D850 and it will be a direct bolt in and you'll be up and running faster.

iangoround · May 16, 2019

North Idaho Wolfman said:
Depending on which D850 you have gotten, Thermosiphon or water pump, it will take different things.

Thermosiphon:
You'll probably just have to swap the oil pan and pickup tube, intake, exhaust, and fan assembly.

Waterpump:
Oil pan and pickup tube, intake, exhaust, add fan, add (if not already equipped) alternator or dynamo, you need to rework the inlet and outlet of the radiator as the angle and the size are different.

If you don't want the task of reworking things, you could simply swap the gear case cover from the D750 to the D850 and it will be a direct bolt in and you'll be up and running faster.

Thanks. I gathered that much from searching around this forum the last few days. The d850 I***8217;m getting looks like it came out of another tractor or mower. The oil filter is on the correct side, it has a shaft for a front pto, and it***8217;s a water pump version. I know it will require some modifying to but the radiator, but I think I prefer having a water pump vs thermosiphon.

I was planning on adding a small 40ish amp a mini alternator to it that I can hopefully fit under the hood.

While I have it out, is there anything I should do or check over? Common failure items besides the obvious old leaky gaskets?

Does anyone make ***8220;go fast goodies***8221; for these engines? The very first thing I noticed looking at the engine is that the flange on the exhaust manifold that the muffler bolts to looks like a very tiny turbo flange and I***8217;m not the sort of person who can just NOT put a turbo on something. Granted I know it***8217;s a tiny Diesel engine in a tractor and I***8217;m not going for records here, but getting a few more ponies out of it so I could run a bigger rototiller and finish mower would be nice.

torch · May 17, 2019

iangoround said:
getting a few more ponies out of it so I could run a bigger rototiller and finish mower would be nice.

Let me play Devil's Advocate here for a minute:

The B7100 is a tough little tractor, but it's the biggest of an aging series. From that, one might infer that Kubota already maxed out the power and that the parts have already been subjected to stress and strains.

Now you are fitting a larger engine, which should bump up your torque just because of the displacement alone. The tractor is not getting any bigger or heavier or stronger. Are you sure you really want to over-stress things further by driving bigger, heavier attachments with a turbo???

If you need bigger attachments, then maybe you need a bigger tractor.

D2Cat · May 17, 2019

Torch, I agree with the points you make about not putting a turbo on the engine. It does create a lot of stress on all moving engine parts, for very little additional power.

However, you mentioned, "...it's the biggest of an aging series." But remember there is a B8200 and a B9200. Both larger than the B7100.

North Idaho Wolfman · May 17, 2019

Depending on which D850 you have gotten, it could be all the way up to 21HP already, that's a huge jump from the stock 16HP that it started with.

I would also suggest a new clutch disk, new pressure plate, new throwout bearing, new Pilot bearing, and pilot bearing dust seal, all three Hydraulic filters.

And lets hope it is a Tractor model, as some of the Industrial models did not have a provision for a pilot bearing, and not having that will throw a huge monkey wrench into the works.

One other Hiccup could be the drive for the hydraulic pump, it could have a much newer drive arrangement, that uses a gear instead of a slot.

torch · May 17, 2019

D2Cat said:
However, you mentioned, "...it's the biggest of an aging series." But remember there is a B8200 and a B9200. Both larger than the B7100.

Sorry, I wasn't very clear. I should have said the B7100 had the biggest engine of the x100 series. The B5100/6100/7100 where all very similar in physical dimensions and capabilities.

The x200 series were physically bigger. Longer, wider, heavier. For example the 3ph lift rating was >1,000lbs compared to 400lbs for the x100 series. I believe the B6200 was least powerful of the x200 family and came with the D850. The B7100 was the most powerful of the x100 family and came with the D750.

My point is that if you want to use implements that need more power, maybe you need a tractor strong enough to handle that power.

North Idaho Wolfman · May 17, 2019

torch said:
Sorry, I wasn't very clear. I should have said the B7100 had the biggest engine of the x100 series. The B5100/6100/7100 where all very similar in physical dimensions and capabilities.

The x200 series were physically bigger. Longer, wider, heavier. For example the 3ph lift rating was >1,000lbs compared to 400lbs for the x100 series. I believe the B6200 was least powerful of the x200 family and came with the D850. The B7100 was the most powerful of the x100 family and came with the D750.

My point is that if you want to use implements that need more power, maybe you need a tractor strong enough to handle that power.

I fully agree, the B7100 has its limits.

That said, both my B's have bigger engines, one a D950 19HP and the other a D850 21HP, and both are doing fine and dandy, the one with the D950 has been used for all sorts of work including 6 winters worth of heavy snow removal.
So I know in my cases they can hold up to more HP than stock.
I wouldn't even consider Turboing them, not because of the HP gain (which is very small, 1 to 4 HP) but because of the heat generated, too hot!

iangoround · May 20, 2019

North Idaho Wolfman said:
Depending on which D850 you have gotten, it could be all the way up to 21HP already, that's a huge jump from the stock 16HP that it started with.

I'm not sure what the new one came out of. The seller - Old Forge Power in Carbondale, PA - doesn't remember now either, but thinks it was some kind of lawn equipment. Is there a way I can figure out the power rating, besides going to a dyno?

North Idaho Wolfman said:
I would also suggest a new clutch disk, new pressure plate, new throwout bearing, new Pilot bearing, and pilot bearing dust seal, all three Hydraulic filters.

And lets hope it is a Tractor model, as some of the Industrial models did not have a provision for a pilot bearing, and not having that will throw a huge monkey wrench into the works.

I was not aware of that. Lets hope. What do if it doesn't? I guess I'd have to either get the crank machined for one or swap cranks?

North Idaho Wolfman said:
One other Hiccup could be the drive for the hydraulic pump, it could have a much newer drive arrangement, that uses a gear instead of a slot.

That sounds like a pain in the butt, but solvable by just buying a new pump, yeah?

North Idaho Wolfman · May 20, 2019

iangoround said:
I'm not sure what the new one came out of. The seller - Old Forge Power in Carbondale, PA - doesn't remember now either, but thinks it was some kind of lawn equipment. Is there a way I can figure out the power rating, besides going to a dyno?

I was not aware of that. Lets hope. What do if it doesn't? I guess I'd have to either get the crank machined for one or swap cranks?

That sounds like a pain in the butt, but solvable by just buying a new pump, yeah?

Send me the Serial # when you get it and I might be able to tell you the HP, these are kind of tough to figure out when you don't know what they were originally used in.

Yea if it doesn't have a pilot bearing, you can swap cranks or have it machined into it.

The hydraulic pump situation could get tricky, lets hope not.
If it doesn't have the slot drive on the fuel cam to drive the pump, then you would need to buy the pump and the gear drive section, that can get pricey, then you would also have to have the hydraulic lines refitted.

iangoround · May 20, 2019

I'm hoping it will be delivered today. Although R+L Carriers are pretending like the tracking number and bill of lading I have dont exist, even though they had no problem looking it up for me last week...

edit: turns out they had the right delivery address under the wrong zipcode, and also the tracking number they gave me is no good. Go figure. Customer service says I'm the next stop today.

iangoround · May 20, 2019

This is what showed up today. I was looking for the serial but I'm not entirely sure where it's supposed to be?

iangoround · May 20, 2019

No hydraulic pump, bit there looks to be a blockoff plate on the back of the injector pump to mount it. I'll pull that off and check out whats behind when I get home from work.

Crank looks to have a pilot bearing provision.

And it even came with an itty bitty alternator.

Gonna go home and unload this, then start tearing down the tractor and moving parts over.

D2Cat · May 20, 2019

In your first picture is the number. Might clean the rust off with a slight cleaning with emery paper. Then to the left, under the injector line will be the rest of the number, I think.

Looks like you got an engine that used a pilot bushing will save a lot of grief.

North Idaho Wolfman · May 20, 2019

Your going to have to pull that flywheel and the blocking plate on the end of the fuel cam to know for sure.

Looks like it already as the dynamo on the side but that won't fit unless you alter the side shield on the tractor.

WORD OF CAUTION: When you install the other flywheel on this motor, hand thread all the bolts in past the collar, if they stop before the are snug then the alignment is wrong, the flywheel only goes on one way, and the holes are super close to looking like it can fit all different ways.

iangoround · May 20, 2019

Here's the crankshaft end.

The serial number I found reads d850-797553

Behind the cover plate is slotted shaft.

Sent from my Pixel using Tapatalk

North Idaho Wolfman · May 20, 2019

Do you have some calipers to measure the hole in the crank, it looks good though.

And yes that's what you wanted to see on the end of the fuel cam!

iangoround · May 21, 2019

North Idaho Wolfman said:
Do you have some calipers to measure the hole in the crank, it looks good though.

Somewhere I should.

I just ordered a clutch kit, should be here Friday. In the meantime I've got to get the tractor split so I can send the flywheel out to be surfaced. For giggles I priced a new one -- almost $700!! I've got a complete gasket kit from Kumar bros for the D850 so I'll go through the new engine and replace gaskets and seals as needed. I can already see the rear main seal is weeping a little bit.

D2Cat · May 21, 2019

Why resurfacing the flywheel? I've cleaned them up and never had one surfaced. They're heavy and don't warp.

North Idaho Wolfman · May 21, 2019

iangoround said:
I've got to get the tractor split so I can send the flywheel out to be surfaced.

NOOOOOO, do not resurface the flywheel!
You can not resurface Kubota flywheels as the tolerances are way too tight, even taking off thousands of an inch off can have drastic effects on the operation, some has gone as far as the clutch not disengaging.

If it's got rust on it use CLR or ZEP Calcium, Lime and Rust remover to get the rust off of it, then lightly sand the surface of the flywheel.

If it's got stress cracks or anything like the such, don't worry about it, just lightly sand the surface and use it.

Common maintenance items on D850 and B7100s?

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