Good morning guys, I have a cat 307C excavator that keeps losing the swing gear oil out of the filler tube/dipstick which is roughly 8 inches tall. It holds .4 gallons going by the manual and during the course of running for a couple hours all the oil will come up out of the dipstick tube. Is there some type of breather vent? Thanks for the help
Good day A possibilty is that Hydraulic fluid may be forcing the oil to come from the dip stick, has the case drain filter been changed recently? Kind regards Uffex
If the motor has lost the front seal it can push fluid in to the rotator gears and cause overflow Easy test ,pop the motor with lines still on and try it , leak will be obvious
Morning uffex, I looking at this diagram, is this considered the case drain filter and it’s location? Thank you Digs2, are you referring to engine oil would mix into the hydraulic, swing engine? Sorry just have me confused.
No case drain filter on this machine Uffex, only a return line filter element in the hydraulic tank. It is located under the circular cover to the right of the one that is shown being removed in the illustration above taken from the Maintenance Manual.
The unit in your picture is the suction screen for the pump. Bob
I am referring to the swing drive hydraulic motor . If the front shaft seal fails oil will likely enter the gearbox and begin overfilling . The chamber in the 307 is small so a small leak will change the level fast . Water intrusion can also raise a fluid level , not that easy but possible .Milky oil would be obvious .
I notice your in mass , If you determine the motor is leaky take it off and Northland and Willette in Plainville,ma will rebuild your motor with all cat seals . I'm sure your familiar with Milton , they get it done too . I prefer the personal experience at a smaller shop ?
Thank you Nigel for coming on board, hands up I do not have a hydraulic schematic to check. I guess it dumps leak-fluid direct to the pumps? Haymaker I guess this has already been straightened out the filter you have illustrated is a suction for the main pump, maybe you can lift the swing motor enough to establish if it is the cause of leakage. Kind regards Uffex
I will definitely buy a new suction filter for the excavator but there are no other apparent leaks anywhere around the motor or seals. It strictly comes out the top of the filler tube, nowhere else. Very strange to me. I look forward to hearing more ideas from all you guys, thank you for your time and your help
If you refer to the O&M Manual the suction "filter" is actually a (metal) screen, so unless it is physically damaged all that will be required is to wash it in some sort of solvent and then replace it using new O-Rings. See step 16 of the procedure. If you find any majkor debris stuck to it then I would suggest you take photos and post them up here.
There is no way that a well restricted in tank hydraulic line Return line element would cause issues with the swing gear, right? Or am I missing something here. Thanks again
Good day It would appear that the Cat machines have a differing concept to the majority of machines in the market all of which use case drain filters to reduce the pressure on shaft seals.I note that the maximum value for shaft seals is quoted by Eaton at 2 bars approximately 30 p.s.i.. Im not sure if the case drain goes returns via the main filters or dumps direct back to the pump inlet (Nige maybe you could clarify). There would be little benefit from renewing the suction filter although the main return filters beneath the circular plate 6 on the tank top may well help depending on the case drain return route. Kind regards Uffex
I think it is just the mini machines that don't have case drain filters in the implement hydraulic system - maybe a space issue or even something related to the size of the swing/travel motors. The larger models all seem to have them. The schematic (attached) shows what I take to be the swing motor case drain line routed straight back to the hydraulic tank.
Good day Nige Thank you for the response, a star of the forum for sure. Kind regards Uffex
The easiest suggestion at this point seems to be pull the swing motor off the top of the gearbox with the hoses still attached, then operate the swing and see if oil falls out of the motor shaft seal. If it does then there's your answer.
Good day Haymaker101 According to the schematic the case returns the fluid via the main filters, for sure in your shoes I would renew the elements. It maybe that you will need to replace the motor shaft seal, establish this by simply lifting the motor and observing if hydraulic fluid is passing the seal. (Nige you are faster at typing than me). Kind reagrds Uffex
Hi Haymaker. If I'm not mistaken, the swing gear oil is coming out of the filler tube ın addition, Is the hydraulic oil level dropping? İf it drops than normal hydraulic level, We can say seal of swing motor/case drain line restriction or demage seals of swivel Did you have the swing drive group overhauled recently? Because, Some repairers put grease under the plenatary group to keep it from leaking oil. As the machine makes swing rotation, the grease rises and out the swing drive oil from the filler or vent pipe. Thanks
Morning everyone, I can only at 2-4 ounces of oil to swing motor and it comes up filler tube. Done this 3 times. This morning I pulled the drain plug and got 10 ounces of oil. Drained very slow because not much oil. When to refill and could only put 2-4 ounces of oil in without it overfilling. What am I missing here? Manual calls for 40 ounces I believe.
What year and how many hours do you have on the machine. According to the specalog for the machine from Cat, the swing gear box holds 1.5 liters of oil. That is about a quart and a half. In my experience with swing gear boxes, they are all planetary units with very little room and no provision for cooling the oil. The oil will get warm and expand. The other issue is when filling the oil, it takes a lot of time for it to drain into the box and fill while expelling all the air caught under and around all that gearing. Draining and refilling the box takes time. The common issue while refilling is air burping up through the fill tube and making a mess. Then people pull the dipstick and assume it is full when it isn't. The other mistake is putting too much oil in the box figuring it will drop down some as it is used, and the box now expels the excess through the dipstick or the breather if it has one. Another issue happening on some machines is that the bottom bearing in the swing gear box may be lubed with grease and not the oil in the swing gear box. An operation and maintenance manual would let you know if that is the case in your machine. A continuous flow of oil out of the breather or dipstick tube would indicate a leaking seal in the hydraulic motor which would force hydraulic oil into the swing gear box. It was mentioned above about the possibility of a case drain filter being plugged. No manufacturer that I have dealt with puts a case drain filter on the hydraulic motors. Cat puts a case drain filter on the hydraulic pumps. All case drains for the motors on machines that I have dealt with go to the machine return filters or the directly back to the tank. Swing motors can be subject to very high pressures when the house is turning and then the control is moved to stop the turning. There are provisions in the motor to handle and vent that high pressure so that it doesn't damage the motor. A blown seal may be the result of a problem in that area of the motor. The motor itself may also have internal leakage on the seal plates or piston and barrel assembly that may cause high pressure in the motor case. If your motor is leaking into the gear box I would suggest a call to your local dealer asking if there are updates to that motor before going any farther. You might be able to unbolt and lift the motor out of the mount on the gear case and then use the machine hydraulics to turn the motor shaft and watch for a leak. Keep in mind though that with no load on the motor, it isn't likely to show a leak from the shaft.
Lot of great info and knowledge, thank you. If there is seals leaking or damaged, would I be able to visually see it from the outside or is everything internal? I’m going to get the excavator back to the shop where I can power wash and further investigate. I’ll add pictures this week. Thanks as always
John C makes a very good point about how difficult it is to drain a small swing transmission such as the one on your machine. Try removing the drain plug and leave the swing gearbox draining overnight to see how much oil comes out of it maybe.? It would also be recommended to leave the filler cap off so that there is no chance of the gearbox sucking a vacuum as the oil drains out of it.
Hey guys So I have tried this 3 times now over the last couple weeks and just want to give you an update. I painfully Fill swing motor until it appears on the dipstick. Takes forever, maybe due to air? I’ve been running machine for a few hours and oil overflows out the fill dipstick tube. I drain the oil from the machine, it takes roughly 15 minutes and I capture about 24 to 28 ounces of oil when measured out. The book calls for 40 ounces capacity, but obviously you never get all the oil out when you do any oil change. The machine is working and acting totally fine otherwise. I feel like I have a block air relief or vent of some sort? Anyone have any other ideas? Hydraulic oil in the rest machine is completely fine. Also, there’s a roughly 1/2” pipe with a plug opposite the dipstick, can I fill the oil through there? Thanks
Hey everyone, I reread all the suggestions and I think that I overlooked one of them. That is that the seal between the swing motor and the Swing Drive is most likely leaking hydraulic oil up through the fill dipstick. I think I am going to get hydraulic oil dye to see if that is the case. also, it sounds like I can unbolt the swing motor from the swing drive and see if it leaks oil, correct?Thanks for everyone’s help
Good day Your suggestion is good, may I also suggest you plug one main line to pressurize the remaining line that will replicate working conditions. See attached Kind regards Uffex
Omitted to mention, a common tip is to warm the lube aids filling via the small fill holes
Pull the plug out and see what happens. Bob
Hey everyone, I know it’s been over a year but hopefully this topic can come back to life. I’ve been adding oil as needed but brought 307C home and put it in the shop to fix. Removed hydraulic lines and swing motor. Does anything in the picture look out of the ordinary? The O-ring felt a little “flat” to me. I assume next would be to clean and remove the bolts around what I would call the gear box. Please advise, thank you!
You took apart the gear box. Wrong component. Your leak is (should be) the seal on the swing motor output shaft. At the arrow.
Oil from above the arrow (hydraulic oil) is transferring to the gear oil (below the arrow). Unfortunately, that seal is only accessed by disassembly of the swing motor.
Topic-check to see if that 307 is made in china--enquiring minds on HeF want to know.
Good day A thought crossed my mind what grade oil are you using to the transmission? Kind regards Uffex
Good morning, Thank you for helping to continue to advise me on this. I think last year when I made the comment regarding the oil coming out of the dipstick, it was mostly because I was overfilling it and then upon running it the oil maybe warmed up and expanded and caused it to come out the tube. Over the past year as I add oil no oil has come out the tube. I am not losing any hydraulic oil. I have been adding caterpillar transmission oil as needed to the gearbox. I am thinking that my next course of action should be to go after the 12 bolts and remove what I think would be called the gearbox? Then I would see if gearbox oil would be getting around the slew ring where there should be grease? Am I thinking through this correctly? Also, no idea if it’s China made. Came from Milton CAT originally. Thanks again everyone
Excellent Reply, thank you for the learning lesson.