640 hydraulic pump

[Tinkerer]

Well, I think the hydraulic pump on my 640 finally went belly up. It has been going for some time now, I have just been ignoring it and hoping for the best! It has been slow, jerky, and sometimes just fine for some time now. Yesterday it quit working altogether, it won't lift at all.

I now get to my question, Although I am handy with tools and mechanical things in general, I have never even had one of these things off of a tractor before. Is it as straight forward a process as it would seem? It looks like I just unbolt it and proceed with the rebuild. Any special tools needed?

 

[slowrev]

Are you sure it is the pump and not a filter or suction strainer plugged ?

 

[Soundguy]

If that is a vane pump.. they were bad about loosing their prime, if there was a leak in the suction line / manifold. Not sure if the 6xx had the piston pump or not. In any case.. i think the parts for the vane pump are hard to locate.. though the piston replacement pump is available.. though.. also hard to locate.

I know of one fellow who makes belt driven engine mounted pumps for people with NAA"s that loose their engine mounted pumps. He even makes up the hoses and fittings to plumb it back into the rest of the system.. etc.

If you have no luck finding replacement parts, let me know, and I'll get you his email address. I'm fairly sure the 6xx and 8xx had a similar hyd pump setup as the NAA.. etc.

Soundguy

 

[Tinkerer]

I am not positive my pump is bad, just my guess. I suppose something could be clogged up, although I don't think there is a filter on my tractor. Mine originally had a vane pump on it, very expensive to fix, but at some point someone has replaced it with the piston style pump that is on it now. A guy down the road has pump kits for about 100 dollars, maybe less. As of right now, I haven't even taken the pump off, just haven't had the time.

 

[jinman]

I had two piston pumps that would quit and both could be started again by bleeding the air out of the system. On the front of the pump there is a socket-head plug. While the tractor is running at idle, remove the plug. Give it a few seconds (it might also be advisable to have a bucket under the tractor) and increase the engine speed a little. If it's air in the system, more than likely you will soon have oil gushing out the plug. Shut off the engine and replace the plug and you should be good to go. If you let the tractor set for several days, you may have to do this each day before you use it. It could get you by for a long time. I did this on and off for two years on an old Ford 4000 and the last time I did it I was showing it to the guy who bought it from me, so he may still be doing it. /forums/images/graemlins/blush.gif /forums/images/graemlins/grin.gif

 

[Tinkerer]

Yeah, I have tried taking the plugs out of the pump and nothing comes out at all. The only way I can get fluid to come out is if I put air pressure in through the dip stick hole.

 

[Soundguy]

Hmm.. might the pickup tube have fallen off? or could there be an obstruction in the picjup / orifice of the pump?

Once you pull it you will know more.

good luck

Soundguy

 

[Tinkerer]

Could be a blockage, or something else besides the pump. I will try to find the time this weekend to get the thing apart and see for sure.

Somewhere along the line, I lost the dip stick for the hydraulic fluid! I remember checking it, then driving it around the barn to park it, but cannot find it anywhere. I am possibly the first guy in history to loose a dip stick!

 

[Soundguy]

Well.. if nothing else.. 3rd.. inline behind me and the owner of my 8n. When I got it, there was a 7" aluminum garden spike nail in the dipstick hole. Bottom of the nail had been marked with a file where 'full' was, and the top had been painted at least twich with the tractors colors.. so it had been with the tractor fo a while.

And then next after me.. I checked the tranny fluid on my dodge ram truck.. went to get gas.. came home, decided to check something else under hood...no dipstick.... had to order one from dodge to the tune of 60 bucks.. figured it was a 'stupid' fee....and I owed it..

good luck on the pump issue

Soundguy

 

[jinman]

Do you have any service manuals for your hydraulics? I think I may have some useful info. I'd be glad to send you some scans as email attachments if you want them. They can sure be handy for troubleshooting. There are lots of pages (at least 20) so I won't try to put them here on TBN.