Cat 318B Swing Motor Leak ( ser-3LR00468)

[Metalman 55]

We were working away yesterday with the excavator when all of a sudden a gusher of oil started coming out of this what I percieve to be a vent for the swing transmission. The one pic where the finger is pointing too is where the oil is coming out. I am thinking it must mean seals on the swing motor failed & it is dumping oil into the swing transmission below & flooding out the vent? Way too hot late yesterday afternoon to touch is so heading back to machine this morning to investigate............... Anyone had this happen.

 

[heymccall]

Yup. Reseal swing motor. Remember, swing brake is in motor, so, ensure upper house cannot rotate before unbolting motor from gear box. Gearbox can be left on machine. Just drain and refill the gearbox.

 

[DoyleX]

Its easy. $100 for the seal and your on your way.

 

[Metalman 55]

Got it off & took it to our local hyd repair shop. Hope it is just a seal.........

 

[Nige]

I was thinkming that too. A seal that lets go over time due to hardening or whatever would not cause the symptoms you described in your OP. I wouldn't be surprised if there are bigger problems deeper inside the swing motor that took the seal out.

 

[heymccall]

Back when I was still green, I had a 322b @ 12k hour do the same. Slipper shoes in swing motor were chewed up, did reman, short time, same failure. Reman again, short time, same failure.

End of story, no matter what, CHANGE the case drain filter.

As it was 'splained to me, when the case drain circuit pressure rises, the motor's piston shoes lift off the plate, and/ or chatter, resulting in piston shoes failure.

 

[Metalman 55]

Case drain filter is totally clean..............stay tuned.

 

[Metalman 55]

The tall hyd filter beside the tank looks pristine, however we did not cut it apart...........plan to change it out next time we are at the machine, as well as draining the tank oil, checking the tank sceeen, cleaning the bottom of the tank thorourly, checking for any fragments in the bottom etc. The hyd place did get back to me saying some of the parts were scored inside & the pdf file is the result. Hope that attachment can be opened ok? I plan to continue diolog with them in the morning as I was not in when they emailed me the picuture & could not look at it & talk at the same time on my phone. I do not understand the internal workings of the pumps & motors, so perhaps this explains a bit?

 

[Metalman 55]

BTW, the hyd shop whom we have dealt with for years can have the parts in 3 days & rebuild for us & I said go ahead. The nearest new motor from Cat is Shanghi & 10 days away, so decided in favor of rebuilding it.

 

[heymccall]

Drain and refill is only if you don't know what oil or how long it has been in there. If you really suspect particle contamination, a different (read more efficient) filter cartridge can be had from Caterpillar to use on a shorter interval, to go cleaner on the oil.
Everything I see says repair swing motor and monitor (oil sample) unit in intervals, including a baseline from the current oil.
But it would also be prudent to replace the drain hoses from swing to filter and filter to tank, especially if they're thermoplastic hoses, like mine had.

 

[Metalman 55]

Oil in tank is not that old & is the correct oil. We changed the main pump about 2 years ago & changed oil then. Tank is already 1/2 empty from the event, so will drain, discard oil, then inspect/clean the bottom of the tank. Will look into the hoses that you mention too. Thanks

 

[Bluox]

Oil in tank is not that old & is the correct oil. We changed the main pump about 2 years ago & changed oil then. Tank is already 1/2 empty from the event, so will drain, discard oil, then inspect/clean the bottom of the tank. Will look into the hoses that you mention too. Thanks

You're doing a good job but may I suggest you remove the grease hole cover for the swing gear and check for hyd. oil in the tub. If there is you might pull the swing gear box and replace the pinion seal.
Good luck
Bob

 

[Metalman 55]

Good idea.....I guess if the hyd motor oil flooded the gearbox with that kind of pressure it could blow out the pinion seal too. Will check it for sure........thanks for the idea.

 

[Metalman 55]

You're doing a good job but may I suggest you remove the grease hole cover for the swing gear and check for hyd. oil in the tub. If there is you might pull the swing gear box and replace the pinion seal.
Good luck
Bob

We took the cover off of the tub below the swing transmission & no oil from the swing transmission got in there so that is good news!

 

[Metalman 55]

Swing motor repaired, installed, all hyd filters except the pilot filter changed, tank cleaned & new oil installed. Ran it for about an hr today & so far so good...............