I'm new to this type of forums. A friend of mine has a bobcat 763 C-series and is leaking hydraulic oil from what I think the service manual calls the hydraulic control valve (pages 79-104). I put a good 5 gallons of hydraulic oil before the dipstick could see any. https://www.usedloaderparts.com/wp-...n-512250001-512450001-512620001-and-above.pdf Attached some pictures of where I see the leak. I'm talking to the local Bobcat parts guy and when I mentioned hydraulic control valve he was like what???. I sent him some pics and I'm trying to see if there's a kit with all the seals and whatever else I might need to fix the leak. Anybody knows if there's such a kit? That might help me guide the conversation with the local parts person. I'm not a Bobcat person so maybe he doesn't understand what I'm saying, I have some mechanic skills (swap/rebuild engines, transmission/clutch, etc) so I was wondering if this is something I should do myself. I borrowed the bobcat and I will like to repay the favor by fixing the leak. Any help/tips/hints will be more than welcome. Thanks! Georgie
Welcome to HEF gsuarez :drinkup Leaking spool seals on the main control valve is as common a problem you'll find on an aged Bobcat. But I never remove the control valve to replace the spool seals, that's more trouble than it's worth. They don't sell the seals in a kit, pretty much just purchase the seals required, and you need to remove at least one of the spool seals for identification because over the years Bobcat used different size/style spool seals and serial number doesn't always identify the correct seal. Here's a thread that will give you a little info about Bobcat main control valve spool seals. > HeavyEquipmentForums
Hi Willie hope you been well, i need a little bit of advice, i just recently purchased a bobcat S100, before i used it checked the lubricants & noticed the hydraulic oil was low added close to 3 gallons & noticed a substantial oil leak coming from the underside of the main hydraulic control valve could this be a leaking spool or something worse? I checked the hydraulic lines coming in & out of the valve & none of them seem to be leaking i am hoping that this valve is not cracked etc what do you think? Also I noticed colour coded zip ties on the lines coming in & out of the valve which i guess means someone has had a go repairing or at least removing the valve, its a 2009 model & worked 1290 hours what are your thoughts would appreciate anh assistance thanks in advance.
Sadly, no way I can say what's leaking mybmw, only eyes on it will be able to determine that. And yes, colored zip ties indicate someone has visited that area before, but that doesn't necessarily mean bad things. Those valves have SAE o-ring boss fittings, could simply be an o-ring on one of those fittings failed. About the only thing you can do is get into it with a good work light and may require a mechanics mirror to determine where the source of the leak is.
After checking around the valve some more, I noticed that it is leaking from a small hole with a plastic plug maybe like a breather that pushes into a hole which is located directly under the valve near the front, could be a a breather for the chamber where the drive chains are located? Also should there be so much oil in there to overspill? it only leaks when it is on unlevel ground & when the engine is not running so the leak is not Under pressure just doesnt make sense
I've never seen an S100 so I'm not familiar with the particulars of the machine. Could you post a pic of the leaky plastic plug and a pic of the general area it's located
i think the control valve sits on top of the chaincase, theres a small breather in the top of all bobcat chaincases. your fluid level should be "within finger reach" of the check plug located in the front of the chaincase. sounds like your chaincase is overfull.... only place for hyd oil to enter the chaincase is through the drive motor seals....
the pics you show are of the drive motor.... the control valve is above and slightly to the rear of the RH drive motor.. if this is a massive leak (that drains the hyd tank in a very short time) i'd bet the hose coming from the hyd pump pressure side to the inlet of the control valve is leaking. it's a VERY common hose to blow on the C & F series mid frame machines. the pic from the service manual you posted showing the little rectangular cover plate is the hose thats probably leaking. feel around carefully along the bottom of the hose ( it rubs against the belly pan and wears through) and you'll probably feel the spot a spot in the hose where the steel braiding is blown out. one hose in particular has a "bobcat only" long elbow on it, even tho it has a parker or gates number on it, it's not available through a distributor... the hose end at the bottom of the control valve is a PITA to get loose, the fitting usually tries to turn in the valve before the hose breaks loose.
Hey Willie, Crewchief, Following up my previous post, the hydraulic drive motors were leaking the hydraulic oil into the chaincase compartment which was absolutely full to the rim so when it was parked at a slight angle it wast leaking from the little plastic breather plug which is located under the hydraulic valve & it just pushes into a hole in the chaincase, I emptied around 13-14 gallons of oil out of the chaincase,as I mentioned before I only just purchased this machine so I did not know any history on it, looks like the mob that sold it to me sold me a lemon & I am pretty pissed some people just have no honour, I have now sent the drive motors to a hydraulic service centre to have them checked out & see if they can repaired being in Australia they are very very expensive for new ones they tell me $3000-$4000 each so will keep you guys posted