tough old 743 kicks control sticks back at me when it warms up and pushing into a pile

[stringgo101]

this is an older 743 serial 5019-m-26352 it runs Great! very powerful and smooth.. till it gets warmed up. about 30 to 40 minutes into running it. it seems to loose pushing power and the control sticks actually push back against my hands when i push into a pile of stone.. i jacked it up and ran it for hours and hours trying to duplicate the problem and it doesnt seem to show itself on blocks? any ideas where to start? i have changed the fluid and filters and removed and cooked out the oil cooler.

 

[waggles]

Your drive pumps need to be serviced. Fluid is bypassing the rotating group. My old 743 had the same symptoms. Heavier oil helps a little but it needs so work.

 

[jerry]

did you also change or clean the bronze filter in the port block?

 

[stringgo101]

did you also change or clean the bronze filter in the port block?

where is that filter?

 

[stringgo101]

where is that filter?

can i service the drive motors or do they need to go to a dealer?

 

[stringgo101]

can i service the drive motors or do they need to go to a dealer?

is that bronze filter under the case drain relief valve?

 

[jerry]

is that bronze filter under the case drain relief valve?

there are a lot of posts on that filter,look especially under posts put up by tazza. If on top of your hyd pump you have a port block about 6 inches square, about 2 inches thick with 3 larger hoses entering it from the right side of the machine. remove the center hose and the fitting. the filter is inside the hole. May have to fish it out with a tool. it is a few inches long. new ones are not too expensive.

 

[stringgo101]

there are a lot of posts on that filter,look especially under posts put up by tazza. If on top of your hyd pump you have a port block about 6 inches square, about 2 inches thick with 3 larger hoses entering it from the right side of the machine. remove the center hose and the fitting. the filter is inside the hole. May have to fish it out with a tool. it is a few inches long. new ones are not too expensive.

mine isnt quite like that. i have a port block on the left side frame. is it under the hose that comes from the reservoir ?

 

[OLE4]

mine isnt quite like that. i have a port block on the left side frame. is it under the hose that comes from the reservoir ?

Bronze filter was on 743's before SN# 15xxx so yours has port block on side and does not have this filter.

 

[frogfarmer]

Bronze filter was on 743's before SN# 15xxx so yours has port block on side and does not have this filter.

The cause if the pushing sticks is a sudden change of pressure in the drive system. If your hydro pumps starve for oil they can act this way. If the drive motors are severly worn internally they can cause this symptom. If your sprockets and chains are worn and slipping they can cause this. If your warning lights work as they should they will indicate a loss of fluid pressure to the hydros. If the machine has good push power with no unusual noise the drive motors are probably good. The sprockets and chains should be very loose and slapping if they are the culprit. Make sure the hydraulic fluid is full and the proper type. Foaming fluid can cause strange problems. A more serious problem could be a slipping drive coupler or coupling between the pumps but it wont slip much before it is gone completely. Check the easy stuff first.

 

[waggles]

The cause if the pushing sticks is a sudden change of pressure in the drive system. If your hydro pumps starve for oil they can act this way. If the drive motors are severly worn internally they can cause this symptom. If your sprockets and chains are worn and slipping they can cause this. If your warning lights work as they should they will indicate a loss of fluid pressure to the hydros. If the machine has good push power with no unusual noise the drive motors are probably good. The sprockets and chains should be very loose and slapping if they are the culprit. Make sure the hydraulic fluid is full and the proper type. Foaming fluid can cause strange problems. A more serious problem could be a slipping drive coupler or coupling between the pumps but it wont slip much before it is gone completely. Check the easy stuff first.

You can replace the wear plates the rotating groups turn on , this will restore the tension on the rotating group but you will probably have to surface the face of the rotating group. Tazza has posted many times about this. Do a search.