2006 CAT 242B Serial Number: BXM03117 I am experiencing a hydraulic oil leak from the gear motor (218-6840) that drives the refrigerant compressor (218-6833) of the air conditioning system. It appears that the leak is coming somewhere between the drive end of the gear motor and the support housing (233-5590). The leak has recently started and occurs when the skid steer is not operational, so it acts like a static leak, possibly from the hydrostatic head from the hydraulic oil reservoir. After cleaning up the leaked area, I estimate that it is a low volume leak on the order of a tablespoon (15 ml) per day. Over a longer time, I have noticed the oil level in the hydraulic reservoir has decreased. I am NOT wanting to repair this leak, as we primary use the skid steer in the winter for snow plowing and round bale handling. Any summer use does not require A/C. My thoughts are to disconnect / bypass this gear motor. I have a CD parts manual for my 242B and have printed out the relevant pages (see attachments) but am not able to identify where all the hydraulic lines run. The gear motor has 3 hydraulic lines connected to it. Hydraulic Line #1 is the feed line into the gear motor that comes from the work tool gear pump. This line is a 0.625” ID x 1500 psi WP. It enters the gear motor on the bottom. Hydraulic Line #2 is a very small hydraulic line (guessing at 3/8” ID), also coming from the bottom of the gear motor, that I have been unable to identify the purpose of. I am guessing that it is an oil return line but I have been unable to confirm this. Hydraulic Line #3 attaches at the top of the gear motor and according to parts diagrams that I have pulled, is the feed line going to the radiator / oil cooler fan motor. It is also a 0.625” ID x 1500 psi WP line. It is kind of a novel approach to route the fan motor feed line from the A/C system but it must save a connection or a hose by doing so. Interesting enough, when I look at the parts manual, this same line is connected directly to the work tool gear pump when the skid steer is equipped with a heater only (and no A/C). Here is what I am thinking to bypass the gear motor and eliminate this leak: 1) Remove hydraulic line #1 (feed line to the gear motor). Cap the gear motor connection. 2) Remove hydraulic line #3 (feed line to the fan) from gear motor and install this line to the tee from the work tool gear pump … it appears to be the same connection but needs to be turned 90 degrees. Looking up hose parts numbers (218-6531 – A/C setup – hose length = 1805 mm / 218-6098 – Heater only setup – hose length = 1855 mm). Hopefully my 2” shorter hose connects up properly. Cap the gear motor connection. 3) Hydraulic line #2 (undetermined line – guessing return line to oil reservoir) – break line and plug and cap connection. Has anyone done something similar in the past? Any tips? Does this sound like a reasonable approach? Can anyone provide a procedure for replacement of the gear motor and / or a hydraulic line diagram? It sure would be nice to confirm my “assumption” for line #2. Thank you in advance for any feedback. Regards, 3CW
Still trying to find out information on what I described as Hydraulic Line #2 above. Looking it up on the CAT parts website (part # 218-6535) only tells me the line is 532 mm long. What I need to know is where is this line connected to / what function does it provide. Thanks!
The small diameter line is a case drain back to the hydraulic tank. You should not need to disconnect it from the motor because once you remove the two larger lines from the motor and connect them together it will have no oil flow to it that would cause it to leak.
Thank you very much Nige. I think I will plug / cap the case drain back line too, just in case the leak is originating from the hydrostatic pressure from the hydraulic tank. Do you know if the supply line from the work tool gear pump would be under any pressure with the skid steer shut down? I will be attempting to relieve pressure before starting this repair by cycling the pilot controls with engine off, key on and brake off. Might you also have any information on the sizes and connection types? I assume these are an ORFC type of connection. Thank you for your support.
That should relieve pressure, but always assume that any hose you loosen MAY have pressure in it even if you relieved system pressure the best you could beforehand. From the parts drawing they appear to be ORFS but I can't see any information regarding sizes.
Thanks Nige. I will check with CAT Parts to identify the cap and plug requirements. Once I complete this repair, I will close out the this thread with the results.
After Repair Post I successfully completed bypassing my A/C Gear Motor in order to eliminate a hydraulic leak, possibly originating from the gear motor shaft seal area. My bypass consisted of connecting Hydraulic Line #1 (feed line into the gear motor that comes from the work tool gear pump) to Hydraulic Line #3 (feed line to the fan). This was done using an O-Ring Face Seal (ORFS) Union of dash size -10, with 5/8” nominal tube OD, and 1”-14 UNF threads on each end, rated for 6000 psi working pressure. In addition, I also capped the two adapters on the A/C Gear Motor using 1”-14 UNF caps. While I was under the skid steer, I also disconnected Hydraulic Line #2 (case drain back line to the hydraulic fluid tank) and plugged and capped each end of that connection using dash size -6, with 3/8” nominal tube OD, and 11/16”-16 UNF threads. On each active connection, I replaced the O-rings with CAT OEM parts rated for hydraulic fluid applications. Two tips I can offer anyone doing a similar repair: 1) When removing the case drain back line, you are directly connected to the hydrostatic head from the hydraulic fluid tank. As a result, you can lose a bunch of fluid while attempting to plug the line, which happens to be in some pretty tight confines. To eliminate this open line from flowing back from the hydraulic tank, I used my Shop Vac with a tapered nozzle inserted into the fill spout of the hydraulic oil tank to pull a vacuum on the tank while I fumbled around plugging the line. I used this technique before when repairing a leak in my pilot controls with good results too. You don’t want to keep the vacuum running too long as limited air flow through the vacuum may cause the vacuum motor to overheat or fail. I could actually hear bubbling of air in the hydraulic oil tank as it sucked air through the open case drain back line. 2) When plugging the first line in the tight confines, I had real problems with inserting a plug into the female swivel nut. Space was tight and it was difficult to get two hands into the small area to both hold the swivel nut and screw in the plug. I eventually got it done with minimal leaks by creating a vacuum on the hydraulic tank as described above. On the next two connections, I placed a zip tie tightly on the line above or below the female swivel nuts to prevent the nuts from moving, which made connecting the male union threads much easier. See photo for more details. Thanks again to Nige for providing the drain back line identification. I would have been working in the dark without your feedback. Photo descriptions: Photo 1 - Possible Leak Point - I'm thinking that the gear motor shaft seals could be leaking, as the leak appears to be coming from the Breather Assembly of the Support Housing. Just a guess based on the observed leak path. Photo 2 - Line 1 and Line 2 - enter the bottom of the gear motor. Line 1 is the larger line (dash size -10, with 5/8” nominal tube OD, and 1”-14 UNF threads) that is the feed line into the gear motor that comes from the work tool gear pump. Line 2 is the smaller line (dash size -6, with 3/8” nominal tube OD, and 11/16”-16 UNF threads) which is the case drain back line to the hydraulic tank. Photo 3 - Line 3 - attaches at the top of the gear motor. This is the feed line going to the radiator / oil cooler fan motor. This connection is also dash size -10, with 5/8” nominal tube OD, and 1”-14 UNF threads.
Photo 4 – shows Line 1 that is zipped tied to prevent the Female Swivel Nut from shifting down, which made it easier to attach the Union in the tight confines. Photo 5 – shows the ORFS Union (dash size -10, with 5/8” nominal tube OD, and 1”-14 UNF threads on each end) that was used to bypass the A/C Gear Motor by connecting Line 1 with Line 3. Photo 6 – shows the Union, Plug and Caps installed and secured in place. No more leaks ... but no more air conditioning either !!