Hello. I have a 980 H Caterpillar and While in operation it blew apart a ORING on l the hydraulic boom . We lost lots of oil and once we fixed ORING and added oil the Park Brake now will not disengage and the boom or tilt will not function at all . If there is any feedback I would be very thankful. Thank you
You've probably lost prime to the pilot pump. Try stamping on the brake pedal several times, that may flow enough oil out of the circuit. If that doesn't work, you'll have to loosen the line from the pilot pump.
CMark thank you for your reply . I will try this and let you know my results. I really appreciate this .
CMark . Is the pilot pump different from the main hydraulic pump and is it located in the front frame area with all of the solenoids. The machine is still in brake lock . Let me know at your convenience. Thank you
I'm not near a computer with my SIS access right now, but from memory, its a small gear pump on the end of the main hydraulic pump stack. Cany anyone confirm?
Thank you I will look in this area .
OK I'm back online with SIS. In the absence of a SERIAL NUMBER , I've taken a guess at an MHG prefix. The pilot pump is item 7.
Thank you CMark . I will source this area and will get back to you . I will post the serial number as well .
put a couple pounds of air pressure onthe hydraulic tank then start and boom up and down
mljohn . Thank you for this advice. CMark I will try upload a picture of the serial number
Same illustration that Cmark posted above is also valid for JMS-prefix. Pump Part Number (Item 7) is 235-6501. Mounting O-Ring is (Item 12) is 3C-3089
Thank you Nige . All you guys are simply amazing. So very thankful I am .
I can't imagine how blowing an O-Ring somewhere on the boom would take out the pilot pump, although if the system ran dry for an extended period that might just do it. often we don't get the full story in cases such as this one.
That looks very close to the 980G II. If it is you better have long skinny arms! Might be best to trace one of the small lines off that pump back to some place you can easily reach to crack it loose to vent some air.
I think Cmark was looking at the possibility the pilot system was air locked and was just pointing to the pump with the idea that if the outlet was cracked open it would be able to pick up it's prime.
I was thinking as well it will be a tight squeeze in there maybe even have to take the rear tire off . We are going to try cracking lines and putting air in the tank first before I get too far into it . We have had trouble with the hydraulic before where it was very erratic in the way the boom would not lower and the tilt would not tilt . Quite possibly the pilot pump could be the problem here . I am very thankful for all of the replies so far . I will keep all of you posted . Thank you .
We had a leak that we thought was at the mounting for either the pilot pump or maybe the transmission pump on our 980G II. Looked in service manual on how to remove pump and the first step was "Remove Cab"! Well we were lucky and it was the off season so machine was not needed that bad so I decided why not! To be honest the hardest part of that job was disconnecting the "quick connects" for the AC system. machine was 11 years old at that time and they had never been touched. What actually turned out to be the biggest part of the leak was the suction line connection to the transmission pump. Seems someone at the factory had used a "D" ring in the suction line that was machined for a standard oring. And it took 11 years to start causing the leak!
Kshansen , thank you for your input. I have had the cab off a 980G before but not off one of these H machines however like you said it is not too bad . I grew up running 100 Hough loaders .... we never had to pull a cab off one these loaders ... thank you
Hough 100's, I never did drugs back in the 1960's but just thinking about Hough 100's or 120's can give me an idea of what a "Flash Back" from bad drugs would be like! Back when I started in the shop around half the front end loaders in the company were those Houghs. Worked on everything from 90's up to the 560's with a couple 400's along the way. Never pulled a cab off one but split many of them to get centers line bored. And had just about every part off them over time. Still have the homemade vacuum device to hold the oil in the tank while removing hoses. If you were careful you could even manage to pull the main pump out of one without draining the hyd, tank. About the worst thing on them was getting one of the Vickers pumps off if they had been on a long time, splines would rust solid in the converter gears. Sorry for getting sidetracked, do you have manual to pull cab if it get to that? I'll check and see if SIS has the step by step. Just took a quick look only 20 "easy steps" and 3,100 lbs! Either I'm missing it but in SIS they can't decide where the pilot pimp is mounted. In parts break down they show it on the back side of the flywheel housing under the cab mounted to the back of transmission pump. But then if you look under "Remove Pilot Pump" they show it like it is on the front side of the flywheel housing. Maybe they got it mixed up with the one on some of the 980G's as that is were I seem to recall it on at least one G.
Yes . I would appreciate a step by step if you can ! The machine never did come with a service manual. I bought it used with about 20K hours on it . Back into the Hough Loaders . My Dad told me about the vaccine cleaner trick for the hydraulic tank to fix main lines etc . The 100s I ran had lots of power . I think the IH engine had 315 Hp where the comparable size 980 only had I think around 280 . I never ran a old B model 980 but I would love to have one in my fleet . Thank you
Good news to all who is watching this post . I was not on site however the men cracked a line on one of the lines and the boom and park brake released once it gained prime . Thank you all for all of the input and I will be posting another thread regarding my 950H . THhis machine is leaking oil heavy from the top crankcase breather and it sounds like it has a constant miss to the engine / fuel . Kshansen I will still take your step by step for cab remove when you have time . Thanks again
Good news the men cracked a line and it gained its prime . Thank you all who has responded to this thread .
That is good news with a heap of bad news attached! Might need a "How to remove engine file next!"
Yes thank you . Once I get closer to that project I will relay you the serial number.
Glad you got it going. These pilot systems are kind of a strange thing in hydraulic terms, insofar as they're a fixed displacement gear pump feeding what is essentially a closed centre circuit. This means they're not always self bleeding.
Thanks CMark . This is valuable information for the next time this happens.
Cmark, now that you mention this I do recall a problem I had with I believe it was a 980G II. I recall doing an oil change on the hydraulic system after replacing filters and refilling tank there was no hydraulic function when restarted. Kept trying things and after a time things started working again. Probably just an air lock problem in the pilot system. Did a little research on the 980G II and found my note about using a pressure test port to bled off oil from the parking brake valve after changing hyd. oil. Might have been a better place to use but it worked for me.