Hello Everyone, I have a 966C with no hydraulics working. After checking oil level and confirming I pulled the pump and found a ton of vein chatter on the pump. I just replaced the pump with a new one and figured I would need to bleed it and top it off with new oil but I am not getting any oil up to the pump. I have started it up and tried to use the hydraulics and I am not getting anything, I pulled the inlet pipe off the pump and found no oil getting to it. I topped the pump itself off with oil and still not getting anything. Any help would be much appreciated.
Was this machine working before you replaced the pump or at any time recently? One thing I would be sure to check is any connections or piping in the suction side of the pump. Many years ago I had a similar problem with a 988A. Replaced hose at the pump and nothing worked after that! Turned out I found where a hydraulic line had worn a hole in the suction pipe to the tank. We were in a pinch and had to get it to wok fast. So removed suction pipe and had a welder braze a patch over the hole in suction pipe, reinstalled and machine was back loading side-dump trailers. Just had an idea, any chance you can make up someway to put some air pressure into the hydraulic tank? Not 100 psi but enough to "encourage" oil to go to the pump. That way if there is a suction leak on the plumbing to the pump you should hear it or see oil leaking out. I would first try this with machine not running.
We had same problem on 980H when changing hydraulic oil in tank. Put 2-4 psi on hydraulic tank with regulator while starting up first time. We took and modified a filler cap to accept a fitting and regulator for air. We would also hook up a quick connect to the pilot pressure test port with a skinny CAT 6000psi hose shooting into a clean pail. This bleeds the pilot pump at the same time. This use to work instantly in 2-4 seconds for the hydraulics to work. It also protects the new pumps and also all the old pumps when doing regular maintenance. That is what I have seen and done. Simon C
Awesome input guys I appreciate it! Good news we found that the gear drive train has busted something hence why our pump is not picking up any oil. Bad news we got to pull the engine. Thanks again for the help!
Just for your info, I have pressurized a hydraulic tank with just a rag ball and blow gun, but need to have somone on the controls that pulls lever to boom up and while it is booming up I shut off air. If they shutoff engine while going up after I shut off air you get less blowback at filler pipe when you let go of rag ball. Then put cap on before lowering the boom. Just to keep you from having a bath. Simon C
Please let us know what you find and if possible post some pictures of what you find! Good luck with the project!
I definitely will get some pictures posted! It's -5 today in Dillingham, Alaska but I will have to get ready to pull that engine out in the next few days. Update you as I go
I'm late getting back to this thread! I wish there was a phone app so I could easily upload pictures quickly. I pulled that engine and found the one of the two idler bolts stripped out and chewed up the crank gear along with the idler gear down so far it wasn't touching the hydraulic gear at all. Got it all put back together with new used gears and flushed the oil a few times along with changing the oil sump screen and oil cooler. Thanks for your input guys!
@kshansen @Simon C
Glad to hear you changed out the oil cooler, they love to collect and drop into the system later. Would be a good idea to look at the mains and rods as well. How hard was it to put on the crank gear, or was it warmed up and pushed on. Have not changed one on I am guessing a 3306 or D333 engine. Glad you found the cause. Simon C
Dang I for got about that one! Glad to hear you got it figured out and fixed!