I am helping a friend work on the power steering on a 416C Cat backhoe. I changed the hydraulic filter and afterwards the powering steering has been giving problems. The only way to get power steering is to run the front bucket all the way up and work it up and down to get any assist for steering. I would appreciate any and all the help. Thanks
Bad resolver seals or stuck resolver ball. Steering valve in Caterpillarese is HMU (Hydraulic Metering Unit?). Try here HeavyEquipmentForums
Thank all of you. The serial number is 4ZN22790 I appreciate all of your understanding because this is all new to me. This is the most typing I have done since high school.
Just getting back. Could you tell me where the hmu is located. I am just starting to try to work on these machines. Any help would be appreciated. Thanks
The HMU is located at the bottom end of the same shaft to which the steering wheel is connected. A word of warning. Diassembling an HMU is not for the inexperienced. It is very easy to reinstall parts incorrectly (the whole assembly has to be "timed" before it will function correctly) and the results of incorrect assembly can be hazardous to your health. For example as soon as the engine is started the steering wheel could start to spin uncontrollably. As heymccall said above, with the symptoms you describe in your OP it is most likely that the problem is NOT in the HMU but in the resolver (shuttle valve) network. If one of those shuttle valves has a leaking seal or a stuck ball it will produce those symptoms. I would suggest to have a good read of the link he posted and come back if you have any questions before you go near the machine with tools.