Just bought 2001 JD 772CH

[BearCreekGravel]

Got a new to me blade the other day, 10k hour 772CH
Went into it knowing it was going to need some work, but all in all I think I did alright on it. Left front wheel bearings were loose on inspection, wheel seal leaked(both appeared to, but this one seemed to show a reason). Was told that it had overheated when in AWD once. I looked at the coolers on the back and noticed they were not super clean, so that’s on the list too. I’ve cruised around the web looking at some forums trying to get some info and thought I’d cast a line here. I found when I was draining the front planetary that there was waaay more than the 3 gallons of oil in it.
I started to wonder if the planetary being completely full of oil was actually a drag on the motor. My only other thought was maybe the shaft seal on the motor is bad and it was filling the hub. I’ll continue disassembling and see if anything else sticks out. I’m the son of a retired 43 year blade operator (he’s 65) and I had a couple reasons for buying this, him being one. I ended up borrowing a blade earlier this year (‘87 140G) and I threw him in it. After running M series since ’09 and being out of the seat for 4 years it took him about an hour to get back in the groove. I knew he was having fun, just a big kid playing in the sandbox.
Any advice or suggestions would be greatly appreciated, thanks.

 

[Diesel Dave]

Welcome to HEF BearCreek .
The 772CH serial # is less than 582129 ?
I don’t believe there is a shaft seal on that front drive motor.

 

[BearCreekGravel]

581680, I am thinking about getting my wheel bearings adjusted correctly and installing the planetary/brake assembly minus the outer cover, starting it and seeing if something is leaking hydraulic oil into the hub. My other thought was maybe supervisor: “that hub leaks, be sure to check the oil” random operator fills it with the plug at the very top.

 

[Welder Dave]

Welcome to the forum! I'd suggest you get your dad on the forum! I'm sure he has a wealth of information that could be very beneficial to everybody else on the forum. I've got so much to learn if it took your dad an hour to get used to antler rack controls again.

 

[BearCreekGravel]

Brought it up to him, told me to search.
New phones and forgotten passwords .

 

[Welder Dave]

Is he interested in re-registering?

 

[Auctioneerhere]

Nice machine, I just bought a 770 BH on a whim & I wish I had an AWD model. Good luck with it, IMO these John Deere Graders are good machines.

 

[BearCreekGravel]

Finally got my shims for the wheel bearings, re-assembled brake piston housing, brake plate and fired machine up. Hydraulic fluid leaking out from the center of the hub within seconds.
Called the local JD mechanic, as much as I like working and fixing my own equipment sometimes you don’t have a choice. And with snow starting to fly time is money. When I get info and hopefully fixed I’ll update. Mechanic remembered one time of converting an AWD into a RWD only machine because of cost of repairs to AWD system (HFWD pump shelled out and a new one was $16k for the pump at the time).

 

[Welder Dave]

That's a lot of money but at least the grader could still be used without the front wheel drive working.

 

[mg2361]

The reason oil comes out right away is that the drive motor's case drain oil is what lubricates the planetaries. So if you start the machine as pictured, then yes, oil will come out. Make sure the case drain line is clear all the way back to the tank. There is also a case drain filter in that line. Make sure that is not plugged creating pressure to cause your seal to leak.

 

[ovrszd]

I'm 73 and ran rack machines for 35 years. Switched to joysticks this Fall. 100hrs in and it's almost intuitive. Your Dad reset himself quickly.

 

[BearCreekGravel]

So this is what was found. Replaced this cylinder block seal plate in the drive motor on the left front. If this piece was available separately it had a price tag of $1100. But…not available as a single piece, had to buy the motor rebuilt kit that is 2 pieces shy of being drop in. So for $3800 I got this plate and a nice cylinder block and piston paper weight. Put everything back together, drove around in 6wd for about an hour with no issues. Hard to tell if anything was getting warm (it was -20 yesterday). My re-tightening left front tandem isn’t leaking anymore either. Now I can move on to sealing up the hydraulic stack in front of the cab, narrowing down the bad injector, and fixing the broken exhaust manifold bolts and gaskets.

 

[ovrszd]

Good progress!!!! Thanks for the update!!!

 

[BearCreekGravel]

Been a while, busy trying to keep everything else productive and dealing with employees. But, an update on the blade. Got the control valve stack re-sealed and leak free .

What I thought was a misfire and possible injector turned out to be some other mechanics screw up. Kinda hard to get the exhaust manifold to seal on the head when you leave heli-coils sticking out. And when you fire it up and crank down on the bolts to try to get rid of the exhaust leaks it becomes the next guy’s problem .


So I pulled the exhaust and intake manifolds to make it easier. Broke a couple easy outs and used a dremel with a carbide bit to get the mass of bolt out. Good strong seal pick threaded out the remnants. Heli-coiled 4 holes and no more exhaust leaks and no missing sound.
The first day of route blading this year didn’t go the greatest. Short driveshaft for fan drive u-joints were out. Quick fix but didn’t get going until the next day.
The machine has been running/working relatively well. If you ever need to replace the fuel return line from the injectors to the tank, it’s Parker -4 push lock hose. Regular fuel line and fuel injection rated line didn’t hold up well.
One more round of blading for the year to waste the windrows and back into the shop for snow equipment install. And maybe see if I can figure out the A/C to help with defrosting.