ford 600 lift

cpk

Member
Hey guys. I have a ford 600 that was hiccupping about every 45 seconds when the lift was raised. The lift actually worked pretty good however I discovered the pump was not pumping very well 100% of the time. I took the pump and had it rebuilt completely. Now for the fun part. As I was asking around about the hiccup situation while the pump was in for repair, I was advised to mix 90 wt oil in with the 303 tractor hydraulic fluid that I was using to maybe thicken the viscosity of the oil and maybe slow down the hiccups. Well I got he pump back on this morning, and it seems to be working well.(barb fitting and hose back to tank). However I now have no lift response at all. I put air pressure in the dipstick hole but no luck. My question is this. Do you think the 90 wt oil mix thing was a bad idea. Is it just too thick to make it through the system? If so what is best to use once I get all that other stuff mostly out as good as I can? It sort of points to the oil thickness since the lift was working before. Any help would be appreciated. Oh one more thing. I mixed a gallon of 90 wt oil in with about 5 qts of 303 hydraulic oil in the hydraulic reservoir.
 
Shouldn't be to thick, my Ford 640 runs 90 weight gear oil for the hydraulics, it lifts and works fine, my lift hiccups about once a minute.
 
On the 53 and up Ford tractors there is a gadget named the unloading valve. It is hydraulically shifted by the movement of the control valve. The control valve does not actually move oil to the ram cylinder. The oil is directed to the ram cylinder by the position of the unloading valve.
If and when the unloading valve stops moving then the lift won't lift until the problem that is causing this condition is fixed.
A faulty back pressure valve can cause the unloading valve to stick.
The unloading valve can stick on it's own.
The unloading valve has an O ring that can become worn until it will not allow the valve to move.
The pump could have lost it's prime too. The piston pump must be bled by opening the front head plug in the pump and running the engine slowly until all air bubbles are gone from the escaping oil. Stop the engine, replace the plug and start the engine again to see if that fixes the problem. It can!


I would first try bleeding the pump by removing the front pipe plug with the allen head hole in it. Start the tractor and let it idle as slow as possible and when all the bubbles are gone stop the tractor and put the plug back in. You will loose about a half cup usually so put something under the pump to catch the oil.
If it won't work then you must go into the lift and take out the unloading valve and clean it up and replace the O ring with the Ford O ring made specifically for the unloading valve. The old part # was NCA 836B. Don't use a substitute or you will be sorry.
The unloading valve is covered by a plate at the front of the control valve housing just above the control valve. Their is a plug over the valve that must be pulled by inserting a bolt with fine threads into the plug and prying it out with two bars or an impact puller tool can be used to snatch it out. The valve can then be pushed out with a punch of the appropriate size. Don't strike it with a hammer. The O ring will be on the unloading valve that needs to be replaced.
If you will look around on the other reference pages of the Yesterday?s Tractor?s Ford forum board etc you can probably find some good views of the lift to give you some idea of what you will be looking at.
When taking the lift control housing off the tractor remove only the bolts that are around the ;outside edge of the housing and do not remove any of the bolts that are inside this circle of bolts. If you encounter a bolt that has fine threads on it put it back where you took it out. The fine bolts hold the cylinder to the cover housing.
Good luck.
 
Hey Zane! its Chris from up South Carolina. We have spoke on the phone a few times. Thanks for the reply. I had already replaced the special o ring on the unloader valve with the correct one from new Holland. I also bled the pump some but didn't see many bubbles. I then plugged my trusty hose barb with hose attached to the bleed hole on the pump and ran tractor for maybe 45 seconds and there was a healthy full hose stream coming from the pump, so I figured pump was ok. I have not got a hold of a pressure gauge to actually check the output pressure of the pump. the lift cover sat on the shop floor since around last October. The pump was in repair for a while and things kept getting in the way of my putting the lift cover back on. I just put it all back together this morning So I guess maybe the unloader valve could possibly be stuck. Hmmmmm. I did pull the pipe plug out of the top of the lift cover aux plate to see if oil was there with engine turned off, and there was hardly any oil there. A trace maybe. So I cranked engine over with ignition turned off to see if oil was getting there and it looked like maybe some oil was trying to get there but not much. The strange thing is the lift worked pretty good before the pump was removed and repaired. Your thoughts?
 
Thanks for the reply! Yes Im thinking the hiccup is just the nature of the beast. I think I can live with that if I can get the lift working again. Again many thanks!
 
(quoted from post at 17:56:53 07/04/18) Thanks for the reply! Yes Im thinking the hiccup is just the nature of the beast. I think I can live with that if I can get the lift working again. Again many thanks!

CPK, why would you say that it is the nature of the beast when someone a knowledgeable as Zane tells you all about how it works and how to fix it?
 
Oh no no no!!! I was replying to Justin wheelers comment about the hiccup thing. Even Zane has told me that sometimes you just cant get that out of it. That's what I meant by the nature of the beast. I hate having to type all this stuff, I would much rather talk to someone. It always seems something gets taken out of context when you communicate by computer. Please don't think I would deliberately try to offend anyone, especially Zane, who knows more about Ford tractors than I ever will.
 

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