jd 440a blade problem

june · December 10, 2015, 09:51:04 PM

hey guys i am going in the garage for a couple of days i want to fix my blade problem

diagnostic is wen i lift the blade it goes slowly and i dont know mutch in general about my hydraulic system so it is hard for me to fix that problem

thanks in advance

lopet · December 10, 2015, 10:20:33 PM

If you want somebody to help you , you gotta come up with some more info. Blade on what ? If it's a skidder, make and model would help.

lopet · December 10, 2015, 10:23:49 PM

Ooops, just saw it's a 440. Sorry my mistake.

Lots of Deere guys here to help you.

BargeMonkey · December 10, 2015, 11:06:31 PM

I'm sure someone has a book for an A-series on here, but check your blade cable and connections first, doesn't take much slack / binding for it to act up.

june · December 11, 2015, 05:12:29 AM

sorry about that it is a 440a john deere skidder in the 70

yes i did check the cable and connection
thanks

grassfed · December 11, 2015, 08:08:23 AM

The blade is supposed to rise in 3 seconds. If it is slow you need to check the hydraulic filters and fluid and make sure that air is bled from the system.

Next would be to check the pump. You need some pressure/flow gauges to check and adjust the pump or get a rebuilt pump.

I suppose it might be the pressure control valve; this valve gives priority to the brakes and steering over the blade function but you need to know that the pump is putting out enough pressure and flow before you blame that valve.

Like others said make sure that there is not something simple that is keeping the control lever from moving completely.

tacks Y · December 11, 2015, 08:16:45 AM

There should be a valve under the hood that changes speed. About 1 1/2" little lever to flip, 2 position. You need clutch out to run charging pump but not sure after that. Is the blade control lever on dash moving all the way? Or is it wore to the point it is hitting on the dash? The hydraulics are way more complicated than needed on the JDs IMO.

snowstorm · December 11, 2015, 09:05:28 AM

if it has the original blade valve its a square valve block. it was way to complex and had lots of problems. i need a picture of what you have. if it is the original then take it off and throw it as far as you can. go buy a new valve and it must be closed center. you can buy a new valve for $150 or so. open center will not work. the priority valve can also cause problems. take the dash cover off and its on the right. you can take the priority spool out and almost everything will work. brakes and blade may not work if used at the same time. mine has been out for 20 yrs. a lot of the new valves can be open center or closed by installing or removing a plug. your jd has a closed center system so there is no relief on the valve its at the pump. a gear pump in the trans feeds the piston pump so if the clutch is pushed to long nothing will work. if the diff lock is on it can make the blade or steering slow. dose it steer ok?

snowstorm · December 11, 2015, 09:10:17 AM

Quote from: tacks Y on December 11, 2015, 08:16:45 AM
There should be a valve under the hood that changes speed. About 1 1/2" little lever to flip, 2 position. You need clutch out to run charging pump but not sure after that. Is the blade control lever on dash moving all the way? Or is it wore to the point it is hitting on the dash? The hydraulics are way more complicated than needed on the JDs IMO.

a lever to change the speed????? never heard of that one before. good point on hitting the dash seen that many times. we are talking about a machine that is 45 yrs ols

grassfed · December 11, 2015, 09:37:31 AM

Just to make sure there is no confusion what I call the pressure control valve is the same valve that snowstorm is talking about

Quotethe priority valve can also cause problems. take the dash cover off and its on the right. you can take the priority spool out and almost everything will work.

I think that bypassing that Valve sounds like a good thing to try; if it works your pump is good and the rebuilt pumps are expensive.

I've never seen any speed switch but there are different holes in the blade control lever that the control rod can be hooked up to. They have different mechanical advantage so you can get more precise control (at least that is what I thought they were for)

june · December 12, 2015, 04:49:36 PM

thanks alot for the precious info sorry about my late reply i was out of town last two days . i just finnish christmas tree cutting . monday morning i will check it out and will keep you guys inform. its is fun to have good reply by you guys thanks again

june · December 14, 2015, 04:50:46 PM

hey guys today i change oil and filter and bleed air from the systeme of the blade. check if level was block from the dash and there was a little improuvement but not enough. by the way my control valve is square. the steering work great and the brake also. i keep reading this post about throwing the control valve but i need to replace in with wat kind of control walve can you refered me to a brand and model please

tacks Y · December 14, 2015, 06:47:16 PM

Adjusting rate of operation.... Remove hood, loosen cowl heat baffle. turn flow adjusting arm on front of selective control valve counterclockwise to increase rate of operation. (per manual) This is the hyd control valve and my A has a 1 1/2" lever on the front of it. Might see looking up on left side of machine with side cover off. Not all machines are set up this way according to parts book. You can change valve with another valve but will have to replumb hoses and make new mount.

snowstorm · December 14, 2015, 07:27:13 PM

Quote from: tacks Y on December 14, 2015, 06:47:16 PM
Adjusting rate of operation.... Remove hood, loosen cowl heat baffle. turn flow adjusting arm on front of selective control valve counterclockwise to increase rate of operation. (per manual) This is the hyd control valve and my A has a 1 1/2" lever on the front of it. Might see looking up on left side of machine with side cover off. Not all machines are set up this way according to parts book. You can change valve with another valve but will have to replumb hoses and make new mount.

if you still have the blade valve that came on it when new. you have a very rare machine. at one time deere had an update kit to get rid of it

tacks Y · December 14, 2015, 07:43:14 PM

Not sure how rare, I have owned it only a couple years. Out of its 40+ year life.

june · December 14, 2015, 08:12:20 PM

i will try that tomorow thanks

june · December 14, 2015, 08:19:11 PM

sorry english is my second language heey . can you tell me were is the flow ajusting arm on my machine. please . thanks in advance for doing it easy for me

tacks Y · December 15, 2015, 08:10:25 AM

A good chance you do not have one, per other posts. Mine is on the hydraulic valve for the blade facing the front. The valve is about 4" square and 8" long. Look for the rod from the lever on dash, follow to valve.

tacks Y · December 17, 2015, 08:19:38 AM

June, On Ebay under JD 440 skidder there is a valve from a A looks to have an adjustment on the end where mine has a lever. Per others here I would put a non JD valve on if I were to replace. Tom

Kodiakmac · November 26, 2018, 06:12:59 PM

Quote from: grassfed on December 11, 2015, 08:08:23 AM
The blade is supposed to rise in 3 seconds. If it is slow you need to check the hydraulic filters and fluid and make sure that air is bled from the system.

Next would be to check the pump. You need some pressure/flow gauges to check and adjust the pump or get a rebuilt pump.

I suppose it might be the pressure control valve; this valve gives priority to the brakes and steering over the blade function but you need to know that the pump is putting out enough pressure and flow before you blame that valve.

Like others said make sure that there is not something simple that is keeping the control lever from moving completely.

Thanks for that. Having a similar problem. What should psi be at when engine is idling?

mike_belben · November 26, 2018, 07:20:04 PM

Pumps make flow and restrictions to flow make the pressure. Youd probably be looking for a flow spec at idle.

I am assuming a machine that old has an open center hydraulic system, which typically only has a few PSI of hose and filter restriction at idle when no functions are selected. i could be wrong, and will let the deere guys take it from here.

More details about the issue always helps people narrow it down.

snowstorm · November 26, 2018, 07:25:12 PM

no its not open center. deere closed center piston pump

snowstorm · November 26, 2018, 07:30:50 PM

Quote from: Kodiakmac on November 26, 2018, 06:12:59 PM
Quote from: grassfed on December 11, 2015, 08:08:23 AM
The blade is supposed to rise in 3 seconds. If it is slow you need to check the hydraulic filters and fluid and make sure that air is bled from the system.

Next would be to check the pump. You need some pressure/flow gauges to check and adjust the pump or get a rebuilt pump.

I suppose it might be the pressure control valve; this valve gives priority to the brakes and steering over the blade function but you need to know that the pump is putting out enough pressure and flow before you blame that valve.

Like others said make sure that there is not something simple that is keeping the control lever from moving completely.
Thanks for that. Having a similar problem. What should psi be at when engine is idling?

you would have to look in the book for the stand by psi. dose it steer ok?

Oliver05262 · November 26, 2018, 10:44:49 PM

Probably is 2100 psi +/- 50

Kodiakmac · November 27, 2018, 04:41:10 PM

Quote from: Oliver05262 on November 26, 2018, 10:44:49 PM
Probably is 2100 psi +/- 50

Thanks Oliver. I couldn't find anything in my Operator's Manual about PSI. And there is nothing in it about bleeding air out of the hydraulic system either.