|
|
| I have been reading on here a lot lately about hydraulic issues and destroking the main pump to solve some issues. I have a tractor that has been acting up randomly for a bit and am thinking maybe there is an issue in the stroke control valve. What is the correct way to do this to the pump? Have the tractor running at an idle and then loosen the jam nut and turn the screw out and then back in? Is that all there is too it? I know I would have to install a gauge in the scv to check stand by pressure when adjusting the screw back in to make sure I get back where I need to be. Am I on the right track? Tia |
|
| |
|
Faunsdale, AL | The screw with the jamb nut that points down from the stroke control housing is the pressure setting.
A destroking screw is installed in the opposite/upper port of the same bore and you turn it in to push the stroke control valve to destroke and then back it out to allow the spring to push the valve back up. I like to destroke it with the engine running. You have to watch out that the front wheels don't move and pinch you when you back the screw out again. Sometimes the hydraulic system will have been dead and destroking brings it back to life so things move unexpectedly sometimes.
If you have no destroking screw/plug then you can remove the valve and reinstall it with the engine stopped and then reset the pressure afterwards. |
|
| |
|
South Central ND | I'm curious if there are two different valves to install because I have an older green valve that I thought I lost one time and ordered a new one and the new one is a bit longer? I've installed it on my 4440 only to find out it doesn't back out enough to engage the pump. Now I end up putting valve in to destroke and then replacing with the plug. It was nice to leave in as it helped with starting on cold days but now I can only use it when the hydraulics act up.
Perhaps I could just file down the new one too?
Edited by Sandcraft 3/5/2018 13:00
|
|
| |
|
West Central Iowa | Later pumps with the serial number tag take a different destroking setup then the earlier non-serial numbered pumps. |
|
| |
|
| So if I want to do it, I have to look at the top of the bore not the bottom? For example, it’s on a 4650 so Idk how I would even be able to get into the that top bore of the valve housing |
|
| |
|
Faunsdale, AL | Looks like a bog standard RE13271 destroking screw goes in it. That one has a hex head screw vs the other type with a roll pin through the threaded stem you might operate with fingers (or pliers in my experience!).
Might need to remove the sheetmetal plate inside the screen under the radiator on left side and foam seals to expose the top of the pump. Usually remove a few bolts and can pivot it out around the radiator hold down bolt or pry up on the radiator slightly and it is notched to slide out completely. It would help to loosen that hold down bolt or remove it.
Seems like there is little to no oil flow through the stroke control valve under normal operation and destroking it a few times allows it to "clear out" and tractor will be fine after that. I have removed the valve on one or two and the oil in the valve area looked dark and a bit sludgy. |
|
| |
|
| Sorry for the long break in between replies but have had a few other things come up. I am going to hopefully get back on that hydraulic pump today. One more question for ccjersey, you said in your last post this 4650 has the standard screw plug not the stem type. Does that mean I can still manually destroke the pump by turning the screw in then backing it out and checking pressure with it running? |
|
| |
|
Faunsdale, AL | Yes, the top of the screw is a hex head vs a stem with a roll pin through it. Works just the same other than that.
The roll pin type appears to be smaller and screws in to an adapter that threads into the housing vs the other type screwing into housing with no adapter. In the past, I have run into pumps that needed the smaller one but didn't know where to look it up. |
|
| |
|
| Thank you for all the help with my pump. I destroked it last night, actually did it a couple times and made a world of difference. Pump had a vibration, three point was jumpy and pressure was low at the outlets, in fact one had no pressure. After messing with it for around an hour, what a difference! Three point is smooth up and down, good pressure at all 3 outlets and vibration is gone. Thank you again to everyone for the help. Hopefully I can return the favor someday. |
|
| |
Educate me on destroking a JD hydraulic pump
