JD 620 Main Seal Replacement

[hbailey]

I have a JD 620 that I believe is leaking oil from the engine into the transmission; the engine gets low on oil after about an hour of running and the transmission was well over full. I have removed the clutch and gear cover, and now need to remove power shaft drive gear to access the seal/bearing. Is there any trick to removing this gear without a special puller?

 

[PJH]

I made a puller to fit behind the PTO drive gear, and also warmed the gear with an acetylene torch. It came off without a lot of trauma. My puller was made out of scrap material, and patterned after the common bearing splitters that you've seen before. I could take a picture of it tomorrow if you're interested. I'm in Southern Illinois - you are welcome to borrow it, but we might be miles apart. About four or five years ago my 630 was leaking a quart of oil per hour. I put new crankshaft seals in it and it will run all summer now without using a quart of oil.

If you post this question down on the John Deere forum, you'll get a lot of advice from some good people.

 

[hbailey]

I was thinking of trying to make something like that, if that works I may try that. Im up here in central Iowa so a little ways away. Thanks for the advice!

 

[PJH]

I found a picture of the puller that I had taken when I was working on my 630.

You'll find a small square shouldered gasket behind your main bearing housing. Ron, otherwise known as Bushhog Papa, has a neat idea to improve that gasket. Apparently, that gasket can swell or otherwise deteriorate and block the oil flow to your right main bearing and right connecting rod. You can add a small piece of common hardware store lamp tubing to keep that oil supply passage open. The engine block is already threaded. Here's a picture of a piece of lamp tubing installed and another piece to show what it looks like. I have a temporary nut screwed on the tubing in my hand to help me screw it into the block.

And here's a picture with the little gasket in place. I have a hard time calling it a gasket - I think of it more as an o-ring.

 

[PJH]

More on the puller - front side

Back side

 

[hbailey]

I ended up finding a gear puller that was just long enough to fit and the gear came right off. The main seal was completely shot so that was the source of the issue. I pulled the main bearing off, the oil seal looked clear and good so I let it go. I believe the tractor sat for years without running before I bought it so I think the main seal sat without oil and dried out. If I ever have to replace the main bearing/crankshaft I will have to add that piece of treaded tube. Thanks for the help!