Boom wont raise on Front End Loader

[dirtranch]

I have a beat up MF3165 with a MF200 front end loader. The bucket will go up and down, but the boom will not lift at all. I changed the hydraulic fluid and filter. I took apart the control valve, and it was pretty beat up. I did what I could to clean it out. The boom still won't lift at all.

Any suggestions for troubleshooting?

Thanks!

 

[Leejohn]

Try running it up for a little bit then check and see if one cyl is warm or hotter then the other. Sounds like a cyl is bypassing.

 

[dirtranch]

Try running it up for a little bit then check and see if one cyl is warm or hotter then the other. Sounds like a cyl is bypassing.

Thank you very much for responding.

I tried to raise the boom for 30-40 seconds. Neither cylinder felt warm. Should I try to check the pressure somewhere?

 

[Tx Jim]

How long since hyd filter in RH photo has been changed? Checking pressure is a good idea. I'd guess pressure needs to be in the 2000-2500 psi range

 

[wdchyd]

......... Sounds like a cyl is bypassing.

x2.......try swapping bucket curl hoses with the lift cyl hoses to rule out valve

 

[dirtranch]

Thank you again for the replies.

How long since hyd filter in RH photo has been changed? Checking pressure is a good idea. I'd guess pressure needs to be in the 2000-2500 psi range

I just replaced the filter and hydraulic oil.

x2.......try swapping bucket curl hoses with the lift cyl hoses to rule out valve

Sounds like a plan, but I'm not quite sure how to do it. The boom has one hose going out and the bucket has two.

 

[Stonehaller]

Since there is only one line connected to the valve, is that is going to the bottom of the boom cylinders to raise the boom. Could a previous own have broken a hose and just plugged the return line on the valve and the cylinders? That would let the boom rise under power and lower with gravity for a while until internal leakage in the cylinder filled the return side with oil. Check the cylinder for plugs in the return ports. They may be at the end of the rods.

 

[dirtranch]

Since there is only one line connected to the valve, is that is going to the bottom of the boom cylinders to raise the boom. Could a previous own have broken a hose and just plugged the return line on the valve and the cylinders? That would let the boom rise under power and lower with gravity for a while until internal leakage in the cylinder filled the return side with oil. Check the cylinder for plugs in the return ports. They may be at the end of the rods.

Thank you very much for your suggestion! The top of the cylinders (end of rods) are being fed by the line coming out of the top of the control valve. The bottom of the cylinders are connected by a line that runs directly between them. Does that mean the all of the power is pushing the boom down, but there's no power to push it up?

 

[Stonehaller]

Does that mean the all of the power is pushing the boom down, but there's no power to push it up?

That would be my guess.

Is there a tee with a capped port in the line between the bottoms of the two cylinders? I suspect that line on the bottom is supposed to be piped to the plugged port on the valve.

 

[4570Man]

Are there any quick connections in the hydraulic system? Look over the lines carefully and see if you can find something that doesn't look factory.