Melroe 500 air in lines

[bpantherone]

I recently purchased a 1964 Melroe 500 Bobcat. Initially the bucket would boom and tilt after allowing to motor and pump to run for about 2 minutes and bleeding the system. I did fill the hydraulic fluid tank up and then forget to put the cap back on before using it. I do have a leak in one of the lines leading to a boom cylinder. I have bled the lines approximately 20 times trying to get all the air out of the system. The bucket will not lift or boom now. Seems like i get a steady flow of hydraulic fluid from the pump, then tighten the pump back up, the bucket will tilt about 2 inches and stop. I go back to the pump to bleed it again, and then more air in the lines. Any advice or ideas on how i can fix the problem would be appreciated. This is the first bobcat i own and trying to find out information about older equipment is being difficult. Thanks for all the help.

 

[antfarmer2]

Fix the leak in the line your sucking air

 

[antfarmer2]

Fix the leak in the line your sucking air

Your cap might not be breathing...........and need to let the air settle out

 

[jerry]

Your cap might not be breathing...........and need to let the air settle out

That is such a simple system there should be no need to bleed air out. Did you fill it till it came out of the lower checkpoint on the left hand side? That's all I can think of is that your oil level is too low.

 

[6brnorma]

That is such a simple system there should be no need to bleed air out. Did you fill it till it came out of the lower checkpoint on the left hand side? That's all I can think of is that your oil level is too low.

I agree with Jerry…..that system is so simple I've never had to bleed one…..new valves, new lines, new cylinders, new pump…..never bled one. The breather cap is not the issue either. Like Jerry said, first make sure you have a full fluid level…..and it's actually the upper checkpoint you should fill to. Jerry knows that…..he just typed it wrong.

 

[jerry]

I agree with Jerry…..that system is so simple I've never had to bleed one…..new valves, new lines, new cylinders, new pump…..never bled one. The breather cap is not the issue either. Like Jerry said, first make sure you have a full fluid level…..and it's actually the upper checkpoint you should fill to. Jerry knows that…..he just typed it wrong.

I did miss type I guess, the lower one is the minimum level. Cant think of any other reason for lots of air in the system other than lack of oil.

 

[bpantherone]

I did miss type I guess, the lower one is the minimum level. Cant think of any other reason for lots of air in the system other than lack of oil.

I did fill it til it came out of the lower hole. Then added plenty more afterwards. Will try to add more to see if that solves the issue after I put the new line on.

 

[gearbox]

I did fill it til it came out of the lower hole. Then added plenty more afterwards. Will try to add more to see if that solves the issue after I put the new line on.

Have you changed the filter under your foot boards . It may be plugged . run the front wheels up on a set of car ramps that will put the filter higher than the oil leval . The filter dosn't come with a O ring order one if you have a leak that you think is comeing from the valves . My parts store can get thew filter and O ring . There is almost no way for air to get in as the oil leval is higher that the pump . the filter is on the suction side of the pump . Gearbox

 

[6brnorma]

Have you changed the filter under your foot boards . It may be plugged . run the front wheels up on a set of car ramps that will put the filter higher than the oil leval . The filter dosn't come with a O ring order one if you have a leak that you think is comeing from the valves . My parts store can get thew filter and O ring . There is almost no way for air to get in as the oil leval is higher that the pump . the filter is on the suction side of the pump . Gearbox

I hate showing my complete lack of knowledge on hydro systems but…..you've got the fluid level up so my next step would be the filter and seals as Gearbox suggested. You can get the filter at NAPA, part #1567….it comes with two seals (O-rings). The seal (O-ring) Gearbox is referring to is a dealer part and is part #6512532 and fits on the mounting "head" …. also replace seal #1567066 (dealer part) while you are at it. You don't need to go to a 'Bobcat' dealer for parts…….just call them and they will ship it to you.

 

[jerry]

I hate showing my complete lack of knowledge on hydro systems but…..you've got the fluid level up so my next step would be the filter and seals as Gearbox suggested. You can get the filter at NAPA, part #1567….it comes with two seals (O-rings). The seal (O-ring) Gearbox is referring to is a dealer part and is part #6512532 and fits on the mounting "head" …. also replace seal #1567066 (dealer part) while you are at it. You don't need to go to a 'Bobcat' dealer for parts…….just call them and they will ship it to you.

After you change the filter if that does not help make sure the coupler between engine and pump is good and then plumb a pressure gauge in somewhere. It could be that the hyd pump is either not turning all the time or worn out.