2240 Hydraulic Pump Noise

[Anonymous-0]

I have a problem with my hydraulic system. My pump has a squeal/shutter sound when no function is being used. You can hear it up near the front and one of the lines from the trans housing to the pump is vibrating along with the line that goes to the bottom of the reservoir in front of the raidator. When I have flow of some kind it gets quite. By flow I mean using the lift, turning the steering wheel or using the scv. I have check the standby pressure at 2250. I have cleaned sump screen, replaced filter, and changed oil. All functions work smooth and strong. I have pulled the stroke control valve and looked at it. The valve itself looks fine. I can't see the seat to tell about it. I have checked the filter bypass valve and it is also fine. I have ruled out the fact that I have a high pressure leak because the sound goes away when I use a function to let the oil flow. It sounds almost like a valve bypassing somewhere. Any ideas...This one has about gotten to me. Thanks.

 

[JDemaris]

That type of noise is just about always caused by the pump being unable to shut itself off. That, due to a leak in the stroke-control valve, or a small external leak that is always calling for a small amount of oil.

Most of the time, it's the stroke-control valve. And yes, I realize you've looked at it already.

Easiest test is to cap all the outlets on the pump so you know no oil is escaping. Then run it. If it's quiet when capped, you know there's a small leak beyond the pump. If it's still noisy - change the stroke control valve and seat (and make sure the o-rings on the seat are intact).

 

[Anonymous-0]

Thanks for the info. I do appear to have very little spray in trans case...it is coming from the scv return...but maybe an ounce a minute. Also the steering creeps from left to right but would probably take it 5 minutes to go from stop to stop. Thanks for the capping idea. That may be my next move. Mine has the 1.38 cid which has the pressed in seat. I don't show any orings for that one in the parts breakdown. Thanks for your help.

 

[JDemaris]

I didn't realize you've got the little German pump. The stroke control valve and seat is entirely different that what's in the bigger USA pumps (2.4 and 3 c.i.).

Those little German pumps tend to hammer something awful when no fuctions are being used. Some did it when the tractors were new.

 

[Machinery-Man]

Ironic to read this post as I just posted similar problem...was working on a mower deck and pounded same with hammer and hydaulic is acting up. Where is the stroke valve? Have order a service manual. Could a jar cause the valve to act up. Can"t tell where my problem is at pump at engine, but seems noisy by the transmission? I have had the hydaulic control off and new seals...maybe I need to go there....any suggestions would be appreciated.

 

[Anonymous-0]

Thanks didn't know that. I really dont' think that I have a rockshaft leak, so I may just cap the scv / steering line at the pump and see if that helps. If it does, I will try to fix those small leaks when I get the chance. I assume it won't hurt anything? Just noisy...Lines don't seem to get more than barely warm after 15 minutes of idling with no use.

 

[Anonymous-0]

Machinery-Man,

The stroke valve is in the pump. It is what sets the pressure for the system. When the system gets to a certain pressure it opens allows the pump to no pump anymore. Left side bottom of pump. It is a big set screw with a locking nut. Possible you blew a seal somwhere else causing an internal leak?

 

[Machinery-Man]

I noticed after my ordeal that the lift didn't want to stay in place and was leaking down faster. Maybe blew the piston seal? I thought it strange that the tractor lift acted up, as I was pounding on the finish mower, was setting on a jack, tractor running weight off lift and it went into a spasm then I moved the lift lever seemed to stop but then seemed to make a noise, like squishing or movement sounded like a fan belt type noise. When you move the control lever activate it would stop but once in position would start again. Jarring the draft control must have caused the problem...

 

[Anonymous-0]

With the tractor running and the lift up take a light and look in the filler neck on the back of the rockshaft housing. If you blew a rockshaft seal.. you will probably see oil spraying. If the lift is leaking down you definely have a leak. They say this will cause that noise. Good luck.

 

[Machinery-Man]

Tim: Took your advise and looked into the housing and could see oil dripping down from cylinder area. I had this off before and put new seals so I pulled the unit off again tonight. Have a tech manual on the way. I think the jarring may have blown and oil rings or piston O ring. Thanks for your suggestion, thank goodness for this site. B/R Chuck

 

[buickanddeere]

My 1640 which is the same Mannheim built engine and tractor chassis as the 1840 & 2040. Has the small eight piston 10.3/11.9gpm pump.
There are squawks, moans and whistles from the hydraulics as well.
Repaired leaks on a pump piston "cap", pump seal line, return line to transmission and the steering pedestal.
Still moans and hums from time to time. For what I paid for it plus parts prices for clutch, hoses, tires,calcium damage repairs, alternator etc. May have well just purchased a new 5203 M4WD instead.

 

[Anonymous-0]

Hope that helps you out. Everything on mine works fine, but it is so noisy. I'm going to do a little more testing before I decide to live with it. I know that I have some small internal leaks...but don't know how small of one will cause noise.

 

[Tx Jim]

Tim Reed,
Your description of how the stroke control valve works isn't correct. When stand-by reaches pre-set pressure,stroke control valve closes. This build up of pressure inside body of hyd pump pushes 4 or 8 pistons(depending on pump size) away from spinning shaft. Therefore pump stops pumping oil. When a hyd function( steering,scv,rockshaft etc.) is operated,pressure drops in body of pump,pistons are spring loaded to go back against spinning shaft and pumping begins again.

 

[Tx Jim]

buickanddeere,
I'm surprised you haven't upgraded your 1640 for one of the 5203's your always trying to push off on someone else. I guess it must easier for you to encourage someone else to spend those big $$$$$$ than you!!!!!!

 

[buickanddeere]

I already have it and it"s fixed up. If I could go back in time doing it again starting out without a "modern" loader tractor. I would purchase a 5203 M4WD instead in a minute.
I would have already traded that 1640 in but it"s also a backhoe tractor with the JD 10A backhoe. I"m looking for mounts to see if the 10A will go on a 5203,or.
Or getting the larger digging jobs done. Then updating the lawn tractor to a 2305 with loader and backhoe with mower. Then trading the 1640 loader/backhoe for a plain M4WD without loader.
For what I"ve ended up putting into my 1981 Uncle"s 1640 which was a "deal". It"s embarrassingly close to the price of a new plain jane 2007 tractor.

 

[Anonymous-0]

I may be wrong, I haven't seen a flow diagram of the pump. I know that when the stroke valve moves it allows the oil to push the pistons out keeping them off the shaft lobe, but what I don't under stand is. When the tractor is off, the spring on the stroke valve is holding it seated. The manual destroker options actually push the valve out of the seat and compress the spring. Wouldn't that be putting the pump in the same mode as it is when it destrokes itself? If so then the valve is unseated therefore open when destroked. I have been wrong before, so I would like to know which is correct. Is the valve seated when no function is being used, or is the valve seated when a function is being used???

 

[Anonymous-0]

Ok, I capped the pressure line from the pump and it didn't make any difference. The line going back to the front of the tranny shouldn't make any difference should it? Isn't it just a return? The sound in more like a squeal or squall. I guess it could be the the stroke control valve. I may put one in it just to see if it helps. I just don't like the sound of it. Thanks for all of your help.

 

[Tx Jim]

Tim,
Its been since the '80s since I was a JD service manager and I have no tech. manual on a 2040 but here goes my thoughts. The stroke control valve stays closed until pressure reaches set psi(2250 from factory) then stroke control valve opens diverting oil pressure to galley(crank case) thus pushing pistons away from shaft. Use a hyd. function and psi drops then stroke control valve closes causing pistons to be pushed against rotating shaft from spring pressure. I think that right but someone correct me if I'm wrong.

 

[Anonymous-0]

Thanks. That makes sense to me. Now if I can just find the cause of my noise. As I have said....I have capped the pressure line to assure that I hav no leaks. The sound doesn't change. It is almost like I'm getting some return back to the transmission on the other line. Is that possible? Is there a valve on that one that could be leaking allowing some return when it shoudl be destroked? This sound cannot be normal. It is a major squeal just like a valve bypassing.

 

[Tx Jim]

Tim'
I remember there's a supply line and a high pressure line on RH side,but is there another one? I don't remember one?

 

[Anonymous-0]

3 lines coming down the right side. Two of them go into the pump and one goes to the oil cooler, aux reservoir and then to the pump. If my service manual would hurry up and get here.