Total System Hydraulic Leak Down

[ThruTraffic]

Mahindra 1626 Shuttle/Gearshift:

- Loader lift cylinders leak down
- Loader curl cylinders leak down
- Backhoe boom cylinders leak down
- Backhoe outrigger cylinders leak down
- The leak down rate is significant. With 1000 lbs on pallet forks you can literally watch it creep towards the ground. A box blade can take the hoe boom to the ground in just a few minutes.

- First visit to dealer shop they claimed leak down was natural. It kept getting worse.
- Second visit to the dealer they replaced the loader control valve.
- Third visit to the dealer they sent the loader lift cylinders out for rebuild. Rebuilder claimed there was nothing wrong with them but dealer had them rebuilt anyway.
- Neither of these 'repairs' resolved the problem. (not sure how they figured either of these would resolve a system wide problem).

- Fluid tank is full.
- There are no fluid leaks.
- All cylinder response is immediate to control valve instruction.

Anyone have an idea as to what would cause a system wide leak down problem like this?

 

[5030]

Sounds like dirt in the valve seats.

 

[oldnslo]

Is this a new low tractor or a worsening problem on a high hour older tractor.

Without knowing valve style and quality it could be just poor quality valves that have excessive leakage. Since system wide this would be my first concern.

Vast majority of functions would have leakage controlled by spool to bore diametrical clearance and overlap length of spool lands onto the bore lands.

 

[LD1]

- Neither of these 'repairs' resolved the problem. (not sure how they figured either of these would resolve a system wide problem).

Clearly you seem frustrated with your dealer.....but this statement shows you dont know a thing about hydraulics. And Im not saying that to be mean.
But the ONLY think in "common" with the whole "system" including the loader and backhoe is the pump and the hydraulic oil.
Seems like they were trying to solve the loader issue first. And they replaced the ONLY TWO things that hold a load.
Unless you have some super low viscosity oil or something.....but I doubt it.

Bleed down IS normal. The issue is.....just how much is "normal".
My guess....simple. Mahindra is a cheap tractor....and in order for them to keep selling them cheap....they sourced the cheapest valves they can.

 

[Harry in Ky]

Clearly you seem frustrated with your dealer.....but this statement shows you dont know a thing about hydraulics. And Im not saying that to be mean.
But the ONLY think in "common" with the whole "system" including the loader and backhoe is the pump and the hydraulic oil.
Seems like they were trying to solve the loader issue first. And they replaced the ONLY TWO things that hold a load.
Unless you have some super low viscosity oil or something.....but I doubt it.

Bleed down IS normal. The issue is.....just how much is "normal".
My guess....simple. Mahindra is a cheap tractor....and in order for them to keep selling them cheap....they sourced the cheapest valves they can.

He's been told that before, but I guess he didn't believe it.

 

[rScotty]

SNIP

Anyone have an idea as to what would cause a system wide leak down problem like this?

Yes. There are a number of members who can tell you exactly what the problem is. The three or four posters directly above can all tell you what it is and how to fix it, as can others. You may not like the answers.

The important thing is how is your tractor running and shifting? All the rest can be fixed.

May I suggest that you do the simplest thing first? That would be to fix the Front End Loader. It's cheap and simple to fix.

First thing is to make sure you are only dealing with the FEL. With only the FEL as an accessory we KNOW we can fix it. After you take off the hoe and its complete valve assembly you should then close the shutoff valve - usually under the seat - that controls the 3pt hitch leak down rate. Check that the 3pt arms stay up.

Now With both of those systems (BH & 3pt Hitch) removed or turned off, Check that the FEL is still leaking down.

It may not be. You may have isolated the problem. But if the FEL is still leaking down - and its leak down isn't affected by the power steering movement, then now we can fix it.

You may have figured out that it is the quality of the internal metal-to-metal clearances inside the machined parts of the loader control valve that have the largest effect on FEL leak down.
To reduce leakdown you have to start with a a good quality loader control valve. These are standard industrial control valves and once you look up to make sure you are getting the correct connector types and threads, you can order yourself a loader control valve online and swap it out yourself. They range in price from about $150 at the low end to three or 4 times that. Get a good one.

Your new loader control valve will also fix the lift arm cylinders. The hydraulic repair shop was correct, they didn't need rebuilding. That was a nice gesture by the shop, but accomplished nothing. If the loader control valve is doing its job, the lift arm cylinders cannot help but do theirs.

You can evaluate the bucket curl cylinders once you get the new loader control valve installed. Bucket cylinder internal seals do matter & they can leak internally OR back through a sloppy control valve....or both. Replacing the loader control valve may be all they need - or the bucket tilt cylinders themselves may have to be replaced with better ones. I wouldn't bother rebuilding them.

Then you can take what you've learned and apply it to the backhoe. It's exactly the same game, but more parts and therefore more costly.
Last comes the 3pt hitch.... and that may be more difficult. Less parts but harder to get to. Do the others first.

Good luck,
rScotty

 

[oosik]

I use to leave the grapple elevated about two feet. Then one day - came around the carport and walked right into the grapple teeth. After nine years - both the 3-point and FEL will remain up - at least a month without dropping an inch. Carport storage seems to considerably reduce dust and grit accumulations.