Broke by Model 48 Backhoe

MMH · Apr 5, 2017

I have a 4500 tractor & a Model 48 backhoe. The backhoe has seen allot of heavy use but is was doing some very light work today. My son was operating it and heard a 'pop' right after he dumped a bucket of dirt and started to swing the boom back towards the hole. After the 'pop' the swing would not work in either direction. In addition, the boom in place (in the swing direction). The tractor back end was uphill & gravity would cause the boom to swing sideways. We could push the boom by hand to center as well.

My guess is that one of the cylinders blew, but want to make sure that it is not the valve or something else. What is the best way to check it out?

beenthere · Apr 5, 2017

With a pressure gauge maybe?

sisupower · Apr 5, 2017

I have rebuilt those valve stacks several times. But could be a cylinder

sisupower · Apr 5, 2017

You will be able to push the backhoe around by hand cause the way the valve stack is. Look under valve stack. Should be some cups under these for each valve. Are any of them leaking?

MMH · Apr 6, 2017

sisupower said:
You will be able to push the backhoe around by hand cause the way the valve stack is. Look under valve stack. Should be some cups under these for each valve. Are any of them leaking?

I would assume that the valve stack is directly under the levers - correct?

sisupower · Apr 6, 2017

MMH said:
I would assume that the valve stack is directly under the levers - correct?

Yes it is. Probably have to remove a cover to see it

texasranger556 · Apr 11, 2017

Are you getting any sort of response when the swing lever is held all the way left or right? Hydraulic relief valve squeal? I would think if something in the swing cylinders broke, you would most likely get an oil leak in addition to delayed motion. The spool valve or linkage coming apart seems most likely.

MMH · Apr 14, 2017

sisupower said:
Yes it is. Probably have to remove a cover to see it

Removed cover and plate that has the swing bumpers on it. The valve stack as six valves and a 'feeder' body where fluid from the pump comes in. The suspect valve is in the middle of the stack. Do I have to remove the entire valve stack before pulling the individual valve bodies apart? It looks like there are two long thru bolts holding all the valve bodies together. Is it a matter of removing these bolts and pulling the individual bodies apart?

If anyone has a service manual or additional advice, it would be much appreciated.

sisupower · Apr 14, 2017

MMH said:
Removed cover and plate that has the swing bumpers on it. The valve stack as six valves and a 'feeder' body where fluid from the pump comes in. The suspect valve is in the middle of the stack. Do I have to remove the entire valve stack before pulling the individual valve bodies apart? It looks like there are two long thru bolts holding all the valve bodies together. Is it a matter of removing these bolts and pulling the individual bodies apart?

If anyone has a service manual or additional advice, it would be much appreciated.

Yea I remove the valve stack and put it in a bench to pull apart. Remove the through bolts and it comes apart section by section. Mark all you hoses good for easy of installing back. Take pictures of the way hoses are routed.