Rebuliding 620

I'm rebuilding our family's old 620 tractor. one of the main bearing locked up. I was wondering if there is an easy way to test the oil pump and lines with the engine disassembled?
 

Spin the distributer with an electric drill. The cam drive gear would have to be removed.
Speaking of cams. They are ignored by 99.9% of engine rebuilders but they are a wear item as well. Having the cam freshened and the lifters trued up is a low cost project. If for some reason you want a little more snort, LP pistons are good for a few more HP.
 
I helped my brother rebuild a 620 a few years ago. That one also had a main bearing problem. Seems to me the seal had shifted blocking the oil passage. I'm sure someone will explain this better and have a way to prevent this happening again.
 
I can't get the pics right side up - sorry.

This is Ron's (Bushog Papa) idea. A short piece of lamp tubing to keep the little squared "O" ring from swelling the passage shut. Picture is of the right side of a JD 630.
a188134.jpg

a188135.jpg
 
(quoted from post at 08:30:51 04/04/15) I can't get the pics right side up - sorry.

This is Ron's (Bushog Papa) idea. A short piece of lamp tubing to keep the little squared "O" ring from swelling the passage shut. Picture is of the right side of a JD 630.
a188134.jpg

a188135.jpg

That looks like a good Idea, were could you get the lamp tubing?
 
The lamp tubing is available in hardware stores, and places like Lowes and Home Depot. If you have a table lamp in your living room, you can probably see an example at the base of the bulb socket. I bought a card of assorted lengths for a couple dollars at Lowes. There are two diameters, and if I remember right, it takes the larger diameter. The tractor block is already threaded. In one picture, you can see a piece of the tubing in my fingers, and there is a nut threaded on the end of the piece. The nut is the thin nut that you find on automotive toggle switches. The threads on the toggle switch nut don't quite match the lamp tubing, and it made the tubing easier to grip while screwing it into the hole. You could probably use pliers to grip the tubing too - it doesn't hurt if you booger the threads, as long as it doesn't stick out enough to prevent the main bearing assembly from seating properly. This is Bushhog Papa's idea.

I turned the pictures every direction, and they refused to post properly. Sorry. . .
lamp tubing picture
 
Hey PJH,

Regarding the lamp tubing fix, which seal causes the problem? The main oil seal in the bearing housing? Looks like that one could only swell inward. I've got a 620 but have never had it torn down to that point so am having a hard time visualizing what is occurring. Wonder if I should take a look at it before it starts causing problems.
 
jjvb - My seals were not swelled shut on my tractor, but others have posted pictures here that show them nearly or completely blocked. The seal in question is the little black ring in the second picture. On the 620/630 tractors, the oil is fed through the block, through the seal, and into the main bearing housing. The little seal fits in a recess in the main bearing housing, and can't swell outward. I don't want to mis-represent myself as a mechanic - I had hoped that others would chime in with a proper explanation.

I tore my tractor down to replace the main bearing seals. The mains were still good, but I was losing engine oil into the first reduction gear cover.
 

Thanks for the Credits guys, I think this could save many rebuilt 620/630 engines..

If engine oil is getting into the Trans, I think it is time to drop the 1st Red cover and make this improvement..

While the 1st Red. cover is off, check the PTO gear engagement for over-travel..

You may want to change one bolt to one longer, with a nut to adjust it to be a "Stop" to prevent over-travel of the bottom engagement..
Mine was and had worn a spot on the lower case from it..

Ron..
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top