another winter, more MLS valve problems...

First off I really don't care if you've had your tractor for 9000 years and ran a billion hours with no mls valve problems.

That said, I just turned 180 hours and my mls valve is done again. This will be the fifth time I have had it out, torn it apart, found nothing really wrong, put it back together, and so far every time it works for awhile after that. It won't go up. If I put the receiver hitch attachment on it it will go up once the oil is warmed up but has a 5 second delay before lifting. With the snowblower on or posthole auger it won't go up at all unless I roll the loader bucket all the way one way or the other to deadhead the hydraulics for a few seconds then let go. Then it will go up about a third of the way, then I have to do it again. So now it's back in the shop to do the same old same old again, and I guarantee it won't last long before it quits working again.

The three point on this thing is pretty much worthless scrap iron.

Sounds like possibly a pressure relief in the valve stuck open...

Aaron Z

The part that really chaps my $^*@&($(&$^ is that when I take the MLS apart all I find that is the slightest bit odd is the spools have the tiniest bit of drag to them when I slide them in the bore. All I do is slide them in and out by had for a little while until they drop right in and it's fine...... for a little while. Pretty soon I'm going to chuck those spools up in the lathe and turn them down a tad. What's the worst that will happen? It won't work? That'd just be a **** shame wouldn't it?

reading your signature, Why not a 72 inch box blade?

If I decide to keep this tractor it probably would be a 72". But I might just as well drag an I-beam behind from a chain because the 3 point won't lift a box blade anyway.

Forgive my ignorance but if taking the MLS valve (whatever that is) apart and putting it back together again restores functionality but only for a short time doesn't that suggest that the problem is actually somewhere else in the hydraulic system? You take out the MLS which I'm guessing would have some effect on the rest of the hydraulics based on your comment that rolling the bucket affects how the 3-pt operates. So possibly a sticking valve somewhere else that comes free when you take the MLS out of the system? As I said, forgive my ignorance if I'm way off base here.

What hydraulic oil are you using?

Rudevette said:

If I decide to keep this tractor it probably would be a 72". But I might just as well drag an I-beam behind from a chain because the 3 point won't lift a box blade anyway.

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Possibly you just hit the problem. If your 3 pt wont lift a box blade, then your Hyd pressure is low. Mine will fully lift a 1000 Lb tiller easily. Have you checked your system pressures, and do you have clean oil in the system.. Also check the hose quick connects. When my FEL started having issues, it came back to several bad quick connects - partially plugged with junk, or totally failed. They check good off the unit, but failed under pressure.

Service guy had a pressure gauge hooked up to a short quick connect to check system pressures at various points. he did need to adjust the pressure relief valve a bit. It was bleeding pressure too soon.

Hope this helps.

Rudevette,
I presume this is on your Bobcat Ct235. If yes I also presume the front loader works fine since you state that you can roll the the bucket back and build pressure.

Since I am not familiar with Bobcat hydraulic system I am going to make a couple of assumptions.

1) This is an open center hydraulic system. I.e Gear pump
2) Pump flow goes to the FEL control and then feeds oil to the 3PH control.
3) The 3PH only has a surge / spike relief and no system relief.

It sounds like you are not getting flow to the 3PH hitch control and that the Power Beyond feature of your FEL control is not working or installed correctly.

I would look at the FEL control to determine where the power beyond port is. Now try and determine where the plug is in the FEL body that is used to convert this valve from non power beyond to power beyond capable. Make sure this plug is installed and that any O-rings are not damaged. This plug isolates the pressure chamber in the FEL valve from the Tank port in the FEL valve. Some use a special fitting, some use a pipe plug installed inside the housing, etc..

good luck

I use bobcat hydraulic oil and bobcat filters. And have changed it twice.

I can almost guarantee that it's a spool sticking in the Mls because after I take it apart and polish the spools up a little bit with a rag and hydraulic oil it works for a little while. The Mls has a pressure relief built into it.

Hydraulic pressure is fine. The loader will lift enough gravel in the bucket to tip the tractor over forward.

I never did get it to work so I took it to a mechanic friend. He took the MLS apart and put it back together and it didn't work. We then called a Kioti dealer and they told us that they "guarantee" it's a bad MLS even if we can't see anything wrong. They told us to pick up 4 new MLS valves, install them one at a time until one of them works then return the rest. He said he replaces the MLS on "a large percentage" of the new units they sell while under warranty and that over 50% of the replacements don't work right out of the box either.

Then we took it apart again, put it back together again and it started working. for now. What I learned is if there is any way to get attachments that you can use without using your 3 point, do that. Protect and save your 3 point for when you really need it and so that maybe it will work on trade in day.

Rudevette said:

I never did get it to work so I took it to a mechanic friend. He took the MLS apart and put it back together and it didn't work. We then called a Kioti dealer and they told us that they "guarantee" it's a bad MLS even if we can't see anything wrong. They told us to pick up 4 new MLS valves, install them one at a time until one of them works then return the rest. He said he replaces the MLS on "a large percentage" of the new units they sell while under warranty and that over 50% of the replacements don't work right out of the box either.

Then we took it apart again, put it back together again and it started working. for now. What I learned is if there is any way to get attachments that you can use without using your 3 point, do that. Protect and save your 3 point for when you really need it and so that maybe it will work on trade in day.

Click to expand...

The Kioti dealer apparently told you to take MLS valves home, try them, find one that works and your problem is solved. Why didn't you try this or better yet, take in in for them to fix and then if it fails it's their problem to make it right.

It sounds as if your going to trade the tractor and if that is the case you may lose a substantial amount of money.

I own the same tractor, same year and have no problems whatsoever with the three point hitch lifting abilities. I can adjust the rate of descent at any time depending on the weight of the impliment and on a regular basis lift a ballast weighing 1000 lbs. This is a good tractor, get yours fixed and save a bundle in the long run by not trading.

Just my thoughts!

Fred

I may be stuck with the tractor for awhile. I was going to trade it for a new Kubota skid loader until I found out how much the skid loader is worth.:shocked: I have a house that's worth less than that!

I talked to a few different kioti dealers and one bobcat dealer and they all told me that sometimes the MLS valves just fail. Even though they have low hours on them they just fail. They said I need to buy a few new ones and try them until I find one that works. I am not going with that theory. A MLS valve is a little mechanical device. It can't just simply go from working to failing in the blink of an eye unless something is broke or stuck.

So I took the MLS valve apart again and started probing every port in the body. To find them I looked at all of the machined holes that are plugged with steel balls in the outside of the body to see where that hole would have been drilled and why. They all made sense but one. There was one spot that I couldn't spot a hole behind a ball plugged machine hole. Certainly kioti wouldn't drill a hole just for the sake of plugging it later so I looked deeper. There is one hole that goes from a valve bore into the center of the MLS body, underneath the center allen screw that holds the end cap on. This hole is so small that the only thing I could fit in it is one strand of copper wire from a 10 gauge copper wire. The wire wouldn't go through that hole. I cleaned the hole out and it is fixed.

Here is the problem with this hole and my theory on why I'm being told to buy MLS valves until you get lucky enough to find one that works. That hole is a drilled and tapped hole that an allen screw goes into to hold the end plate on that holds the valves in. The bottom of the allen screw goes right to the very edge of the tiny oil hole and also plugs the hole on the top. The allen screws have locktite on them. When the screws are put in the hole at the factory little bits of locktite get into the oil hole and plug it up. That's what was in mine and the piece that it takes to plug the hole is so small you can barely see it. I cleaned it up and put it back together without locktite.

One of three things should happen on these valves. Drill the oil relief hole out to a larger size, or don't use locktite, or use a shorter allen screw. Or just drill the hole larger and use a shorter screw would probably do it too. This is just simply a bad design.

I posted my findings for those of you who look this topic up doing a search in the future.

Also, I edited this post to add the following:
Of all the dealers I spoke with what I found is that most of them were not knowledgable, didn't want anything to do with a bobcat tractor, or were very condescending with an underlying tone of "bring it in here, don't call me asking questions". I said most of them because I spoke with the fine people at MICHIGAN IRON AND EQUIPMENT and got some help that I needed. The people at Michigan Iron are very kind, knowledgable, great web site, prices are good, and they just seem like they want to help, even if it's just a matter of talking through a problem. All of my parts, filters, and now a joystick operated loader mounted hydraulic remote are going to come from them from here on out. Check them out. You can find their link right here on this site.

Thanks for the update! Always good to hear about a reliable dealer.

Rudevette said:

Here is the problem with this hole and my theory on why I'm being told to buy MLS valves until you get lucky enough to find one that works. That hole is a drilled and tapped hole that an allen screw goes into to hold the end plate on that holds the valves in. The bottom of the allen screw goes right to the very edge of the tiny oil hole and also plugs the hole on the top. The allen screws have locktite on them. When the screws are put in the hole at the factory little bits of locktite get into the oil hole and plug it up. That's what was in mine and the piece that it takes to plug the hole is so small you can barely see it. I cleaned it up and put it back together without locktite.

Click to expand...

Sounds like you found the root cause.

I am not a big fan of Locktite myself. And on hydraulic components? Hmmmm.