Yet another hydraulic leak.

My CAT307SSR is, after all, 32 years old, so I suppose this all comes with the territory. Yesterday it turned out I'm about to have to deal with the last rebuild of cylinders before coming full circle - all of them developed leaks at the gland-nut pressure seal within the last few years. While poking at that cylinder leak, I noticed the hydraulic swivel joint has begun to drip or maybe even gush a bit. Since the machine is sitting off-level, the leak is pooling on one side of the center dish/well before working its way down here and there, dripping off the frame, and it was probably pretty fast when it was ongoing (I raked out a lot of oily leaves from below). Perhaps the leak relates to my having swiveled the machine 180 degrees a month or so ago, to reposition for re-installation of the dipper cylinder and other components - the first movement in a LONG time. Photo is from below the swivel, of course. Leakage is spreading over the steel "dish" that comprises the central structure of the car body. I think I understand how the swivel works and that internal leaks could create unexpected movements as the lines are crossed over, but I don't get how the leak makes its way outside the swivel unit proper...does it have to blow an o-ring or some such to escape? The swivel almost couldn't be harder to get to from above. It's probably more than arms-length down with no access from the sides, stuffed in between the end of the boom and the swing motor (not sure if I can even get a photo that's recognizable - it's a well of darkness criss-crossed by hoses). Is it ever possible to rebuild by pulling the center out from below? After the attached photo was shot, I did my best to wipe it down from below, thinking maybe it's worth firing it up again to see if there's a clear leak-point - but maybe that's just asking for another big mess and I should just get on with removal? I have uncomfortably little room to get in there even from below - it's pretty claustrophobic - but I suppose I could manually jack the whole machine up and get some cribbing under it if that would make the process easier. Please share your recommendations.

I didn't get a response from anyone, so maybe this isn't a frequently-required task...? I've attached two photos from the topside, after an hour of vacuuming out leaves and such to even make the swivel visible. I'll probably pressure-wash to blow the stuck gobs of crud out before wrenching, and I think I'm short on line-plugs... In the absence of other input, I'm thinking I'd remove 3 + 3 + 2 hoses from topside, then the corresponding hoses below, then the three bolts from below, which...would allow this diablo to come out from the top, I'm guessing? Any particular concerns about fluid drainage (that could surprise me or get out of control?) I'd guess I'll need to ensure there's no residual pressure on the stabilizer cyls - and that the drive motors won't hold pressure...and that the drains can't siphon anything back at me? Really I'm worried about getting my arms where they will need to be to do this. I think even lying flat on my stomach on top of the machine, I will have to stretch to reach much of the swivel. And what's up with that fat black grommet-like ring around the base? View attachment IMG_6574.JPG View attachment IMG_6575.JPG

Sometimes it can take a few days to get a response, especially on a machine that isn't really common for forum members.

I did the swivel seals in our 307ssr a few years back. To do any thing with hoses in that hole its a stand on you head affair. It wasnt fun but was only a 3 or so hour job i had it done in one evening.

Never pulled one on a that small of machine. But there are some common things to be done on any of them. Before you do anything, make sure you can get parts for the machine. The SSR models were always gray market units in the US. Nige might come along and give you a serial number that is of a clone of your machine and give you a number you can work with. Your machine appears to have a swing pinion gear tub that the swing gear rides. You might have oil leaking from the swing gear reducer filling the tub and seeping through the bolt hole. Are you loosing oil from he reducer or is it overfull? I only know of one make of machine where you can separate the halves in the machine and install the new seals. It isn't Cat. I believe you will have to remove the unit from the machine to repack it. Before removing the swivel, make sure all the residual pressure is out of the hydraulic tank by taking the cap loose. The two hoses attached to the top of the bolt on plate are the return to tank. If they are long enough you can just lift them up so they are higher than the level in the tank. You will need some way to mark the fittings before you take them loose. It would be nice to have all the caps and plugs for the hoses. If you do get them I would stamp numbers onto them. I've usually not had them. You will leak some from the hoses but it is a slow leak. Working underneath the carbody sucks. You will get soaked in hydraulic oil. You are at a bad angle to break the fittings loose and you might leave some skin under there when they come loose all of a sudden. Those three bolts on bottom probably anchor the lower part of the swivel. There should be something that holds the upper as well. Usually it is some kind of bracket and a pin on the upper. Tearing down and repacking the unit is pretty self explanatory. It will likely take a lot of force to push the two halves back together. I've used a press, wood and a hammer and one time in the woods in Southeast Alaska I used a Volkswagen jack from a Beetle that happened to come up to us when we had the road blocked. That's a story for a different thread. Good Luck!

John C. said: one time in the woods in Southeast Alaska I used a Volkswagen jack from a Beetle that happened to come up to us when we had the road blocked. Click to expand... Awesome...wasn't that a scene in an episode of 'Northern Exposure' back in the day? Thanks for the very useful insights. I'm a firm believer in labels for everything, especially because my quick turnarounds sometimes run months...even years...and only my old photos can save me if no labels remain. Swing pinion gearbox: I have a shallow understanding, but it's almost a given that I've got one, no? That is, in order to get the needed torque out of a small motor, it's gotta be geared down? Anyway, there's what look like TWO dipsticks. It's dark out now or I'd get a better photo, but the newly-attached one shows the motor/gearbox (I think). The obvious dipstick is taller but the finger-ring is out of the shot behind the shorter one; it reads considerably above the line. I filed that under "huh. I wonder why" the other day when I checked it - sure wish I had a manual, even if in Japanese. The shorter looks like a thread-it-off dipstick, but I think I stopped short of pulling it off until I pressure-washed - then didn't get back to check it. Anyway, I didn't follow your thinking regarding the losing/overfilled conditions (and don't get why I've got what look like TWO dipsticks - yeah, three if I'm included...) I take it you're looking to account for low lubricant, but what of the "too high" condition? Wondering again if I should risk another mess by starting it up and swinging a bit to see whether there's any oil showing up topside, now that it's cleaner and it could be seen, and maybe also get confirmation that it's isolated to the swivel, and maybe where it's first visible? I've got a mortar-mixing pan I would put below the likely-leak areas...

Tyler d4c said: I did the swivel seals in our 307ssr a few years back. To do any thing with hoses in that hole its a stand on you head affair. It wasnt fun but was only a 3 or so hour job i had it done in one evening. Click to expand... Thanks Tyler, that's encouraging, in a way...I don't suppose you have the seal info handy? You been fumbling through maintenance tasks like this by seat of the pants, or got a real FSM of some kind? Knowing where the crossover is between other 307 variants would be really useful, but I don't carry that knowledge around myself, that's for sure.

John C. said: Your machine appears to have a swing pinion gear tub that the swing gear rides. You might have oil leaking from the swing gear reducer filling the tub and seeping through the bolt hole. Are you loosing oil from he reducer or is it overfull? Click to expand... I should mention, if there was any doubt, that if oil had been leaking topside, it would have also been visible also as a sort of waterfall coming out of a narrow drainage tunnel below the boom, which provides both drainage for this "pit" as well as passage for two hoses. But I'm still not sure where you were envisioning a potential leak path.

John C. said: Are you loosing oil from he reducer or is it overfull? Click to expand... Pants said: Anyway, there's what look like TWO dipsticks. It's dark out now or I'd get a better photo, but the newly-attached one shows the motor/gearbox (I think). The obvious dipstick is taller but the finger-ring is out of the shot behind the shorter one; it reads considerably above the line. Click to expand... It just took a pair of Channelocks to twist the black capped one off, and I think it's the filler port (should have suspected that.) There's some pasty evidence of water having gotten into it, but the dipstick isn't milky at all. Any idea what that lube spec is?

John C. said: There should be something that holds the upper as well. Usually it is some kind of bracket and a pin on the upper. Click to expand... From another position, I was just barely able to see a tab sticking off the bottom, below one column of hose connections, so looks like you'd expected. The wide rubber-looking grommet-like deal is indeed rubber (per probing with a crowbar) but there's no sign of it when looking from below. So I sure hope that doesn't mean there's a cavity between the upper and lower plates - couldn't help me any - and it would provide another potential path for the leak to travel, so I could end up barking up the wrong tree by taking out the swivel without better diagnostics. The more I think about it, the more I believe I need to:

• raise the boom a bit
• check for new leak, and if none, then
• swing a bit
• recheck for leakage ...and use that to help pinpoint. Other ideas welcome.

If it were me, I would be checking for the leak origin some more. You mentioned the rubber grommet and a cavity - are you familiar with how the swing drive motor (I think John c referred to it as reducer) are you aware of how it drives a gear pinion which locates into a ring gear on the lower half (the carbody half)? So that ring gear sits in a tub, and that rubber grommet on your swivel stops rain water flooding the tub. The tub has a quantity of grease in it, there will be a rectangular plate to inspect the grease, probably somewhere at the base of the boom where the pins and boom mounts. A 3 or 4" rectangular plate with usually 2 bolts fixing it. So find that and look in there - if it's milky rusty looking grease then no oil leak going through there, but John C was alluding to the fact that commonly the pinion gear seal on the bottom of the slew motor/swing drive motor starts leaking, it starts filling the slew gear tub where the grease is, then shows itself dripping below or through the slew bearing. Something like that. If it's just grease with no oil, then try and track down where your leak is coming from, or if it's minor leak then whether you can live with it a bit longer.

Under the long rectangular cover is the smaller inspection plate, directly below on this machine. It's not CAT but it's another similar size Japanese machine.

Slew ring and tub where the grease is on a larger machine, the hole in the middle is where the swivel union is bolted through.

If you pull the swivel be sure and mark the top and bottem in their relation to how their turned ,bought a 220 komatsu once that we got a good deal on because they had put it back together turned wrong, seems like to get it to go straight it was one lever forward and one backwards

Also crowfoot wrenches are your friend here

John Shipp said: If it were me, I would be checking for the leak origin some more. You mentioned the rubber grommet and a cavity - are you familiar with how the swing drive motor (I think John c referred to it as reducer) are you aware of how it drives a gear pinion which locates into a ring gear on the lower half (the carbody half)? So that ring gear sits in a tub, and that rubber grommet on your swivel stops rain water flooding the tub. The tub has a quantity of grease in it, there will be a rectangular plate to inspect the grease, probably somewhere at the base of the boom where the pins and boom mounts. A 3 or 4" rectangular plate with usually 2 bolts fixing it. So find that and look in there - if it's milky rusty looking grease then no oil leak going through there, but John C was alluding to the fact that commonly the pinion gear seal on the bottom of the slew motor/swing drive motor starts leaking, it starts filling the slew gear tub where the grease is, then shows itself dripping below or through the slew bearing. Something like that. If it's just grease with no oil, then try and track down where your leak is coming from, or if it's minor leak then whether you can live with it a bit longer. Click to expand... Great stuff, thanks John. With the benefit of your slew-ring photos I can now visualize better why the "dish" configuration exists. And indeed, there (was) a sad, encrusted mild-steel plate just left of the boom cyl base that I recall opening some years back, replacing the bolts with SST and not at the time having any SST plate or thick sheet to swap it out - it seemed terribly likely to rust through when I'd least expect, and allow all kinds of crud and rainwater into the ring housing. I took the time this AM to follow through, and now pretty sure that new SST plate and its bolts will be the last trace of this machine someday. Inside, there's not much of a view. The slew ring is uppermost and dominates, and is indeed grease-coated, not wet. But I'm going to have to wait until batteries charge to see if my old scope still works and would thereby let me see better within the dark depths toward the center. I do see daylight coming up from one of the three holes seen in the dish from below, so it confirms the layout for me, as you explained. (I'm guessing they're there as telltales, so that if they're seen dripping oil, it's a clear indication that the leak is from that pinion seal?) But there's enough un-viewable low-point, since the machine is on a forward slope, where a leak from the pinion seal would maybe pool up against the bottom of the ring on that side. I do see some oily wetness within, but can't see much other than the central area. I could also prolly just dip a chopstick into the unseeable part and verify there's not a pond there. Other hydraulics served thru the swivel are just track drives and stabilizer-blade cyls, right? My tracks are off, so the motors haven't moved for a LONG time...so I'm thinking it might make sense to first see whether the machine will maintain an elevated position using stabilizer cylinders? (If I see it flowing out the bottom right after that brief operation, without any swinging, seems like that would be definitive.)

HATCHEQUIP said: Also crowfoot wrenches are your friend here Click to expand... Thanks for that. My collection of crowfeet is matched in number by the ones next to my eyes, so I may need to order some up unless I'm extremely lucky. This is one of MANY times I'm glad I don't depend on income from this or my one other machine.

Pants said: I do see some oily wetness within, but can't see much other than the central area. I could also prolly just dip a chopstick into the unseeable part and verify there's not a pond there. Click to expand... The chopstick test yielded no "pond" of oil next to the low-point on the slew ring - just some not-so-pristine grease and rusty grit with a few spots of oily-looking stuff. Before I launch into another wrenchathon, I'm still hoping to understand how to differentiate between a leak from the drive-motor pinion, and one from the swivel. Wouldn't both sources end up dropping into the cavity above the "dish," adjacent to the slew ring, and be almost impossible to tell apart, since they'd both present as just drips from the bottom of the dish? I'd hoped to check this out internally with my old videoscope, but it's probably kaput from what I can tell.

Shame your videoscope thingamy is kaput, I've not used one but if it has focus you should see oil dripping off one or the other. When you slew about, how much oil is pissing out? It sounds like it's a hard-to-spot amount. I have used various small mirrors and flashlights to get a view in these spots. I'm also a practicing pragmatist in the theory of leaving it until it shows up more obviously, when you can't find the damn thing

Why are your tracks off? Maybe get the tracks back on and give it some run time, look for the leak once it's mobile.