John Deere 2140

bgmillar · Jun 4, 2012

Hi There,
I have a John Deere 2140 that front end loader works fine as does rear mounted post driver but frequently the rockshaft (lift arms) will not lift the post driver at all but occasionally I can get it to lift by activating the loader or post driver controls! I have replaced oil, main filter, checked screen adjacent to main filter and all fine. Any helpful suggestions would be appreciated. Thanks. Barrie.

Tx Jim · Jun 5, 2012

Sounds as if post driver valve and possibly ind loader valve(if equipped) are open-center instead of closed center. Also with 3pt lever in raised position with engine running,look inside hyd filler hole with a light for "spraying oil".

bgmillar · Jun 6, 2012

Preiously looked in filler hole for squirting oil but looked ok with only odd dripping happening. I assume valve setup to be ok as I have been using machine (over several months) and have whacked in about 100 posts but occasionally it just wont lift without raising/lowering loader (which works 100% of the time) but from timr to time it wont lift even doing that yet the post driver controls still work! Is there something in the rockshaft housing which may cause this I wonder Jim?

Tx Jim · Jun 6, 2012

Disconnect return hose from tractor to loader valve,aim hose in a 5 gal bucket or hyd filler hole,with both hyd valve levers in neutral start engine and if oil flows out of return hose the loader control valve is open-center and the problem.

bgmillar · Jun 7, 2012

Today I started tractor with hose into bucket but was only a very minor flow (about 1 cup over 4 - 5 minutes) and then checked in refiller hole but certainly no spray evident at all. What surprised me tho was that everything worked perfectly and raised postdriver about 15 times no trouble so this confirms that the fault is certainly intermittent. I have previously had the problem at end of day and went and tried it first thing next morning when all was cold and it still didnt lift then. I cant trace any info on hydraulic circuitry that operates the rockshaft so am in the dark about valves etc that may be the cause of my problem.

Tx Jim · Jun 7, 2012

Sometimes the stroke control valve in main hyd pump can get worn and hang up a bit. You might consider replaced stroke control valve. How many hours are on the tachometer? Parts key # 20 are the control valves for rockshaft. Where is lever(parts key #1 in 2nd schematic setting)? If not in "D" put it in "D"

bgmillar · Jun 7, 2012

Hi Jim, At a mechanics suggestion I replaced the main pump load control valve although I did not replace the seat as that requires removal of pump to press out and in the new one. The valve showed where it was contacting seat but did not think it was significant and it did not affect my problem.
My machine does not have an hour meter as part of the rev counter but best estimate is its 1985-87 vintage and has seen many hours in the field!
I assume you mean D is the lower position available which is Depth Control?

Tx Jim · Jun 8, 2012

Yes "D" stands for depth. IMHO replacing SC valve without R&R of seat is similar to overhauling an engine and re-using old rod brgs.

bgmillar · Jun 8, 2012

Yes Jim I agree that not replacing seat perhaps is not the smartest decision I ever made but as I said at the time removing pump was a bigger issue than I was prepared to tackle but may revisit the idea after your comment! The fact that the other services operate normally at times when rockshaft will not raise - could that preclude the SC Valve contributing to the problem I wonder? Or does the rockshaft cylinder use a much smaller amount of fluid and hence not lift SC Valve off its seat 100% of the time?

Tx Jim · Jun 9, 2012

Have you checked stand-by pressure with a gauge??? It needs to be 2250-2350 psi. Yes I think RS piston would require less hyd oil to operate than loader or PD.