Cat 299D2 XHP S/N DX200548 When I use my mulcher on the Cat 299D2 XHP, the o-ring on the high-flow male connector starts leaking hydraulic oil to the case drain line. I first noticed this after I used the mulcher for a couple hours and then attached the grapple to the standard flow connectors. The grapple slowly closes on its own. I can use the grapple for weeks after installing a new o-ring on the high-flow connector and the grapple stays open without leaking down. If I use the mulcher for a couple hours and then connect the grapple, it won't stay open. If I continue to use the mulcher for more than a few hours, the pressure to the case drain line gets high enough that the case drain relief valve on the mulcher starts blowing hydraulic oil. It appears that this bad o-ring on the high-flow male connector allows oil from both the high-flow and standard-flow connector to bypass to the case drain line. This high-flow connector screws into a coupling assembly (part number 474-2124). Is it possible that this coupling assembly has a ding wherever this o-ring seats which is causing the o-ring to blow? The coupling assembly is $674, but I'm tired of pulling the connector and replacing the o-ring. Any other suggestion? Thanks, Michael Jones
Post a photo of the coupler. Someone will most likely be able to point you to a generic equivalent of the Cat Part Number.
I replaced the actual coupler with a new one and that didn't affect the problem, so I was wondering if the problem is with the coupling manifold that the coupling screws into. Here's a picture of the coupling manifold (474-2124) with the high-flow and case drain couplings installed. Looking at this picture, the end of the male coupling with the o-ring may be sticking out of the back of this assembly and seat into another connector. Can't tell from the parts diagram.
A tube assembly, part 458-6668, attaches to male coupler at the back of this assembly and may be the problem. It appears to be what seats on the o-ring.
Is it possible that excessive heat is ruining the o-ring and maybe try a better style of o-ring? I know that mulchers generate a lot of heat. Maybe a Nitrile encapsulated o-ring?
Have you made a close inspection of the mating faces of both the tube and the coupler where the O-Ring seats for any defects.? The 7J-9108 Part Number called out in that location is a 90 Duro nitrile O-Ring for a Dash 14 ORFS joint. The use of a generic O-Ring in this location could possibly be a contributing factor.. I would also imagine that the size of the O-Ring (should be 15.72mm ID x 1.78mm cross section) is also critical.
If you keep failing at the arrow, are you using Oring and backup ring?
Does the OP have that style of coupler.? I thought it was one with an ORFS connection.
This is the connector. Part number 373-6970. I have a few of them that I swap out. The o-ring on the bottom end is the one I have to replace each time. It sits in a groove and is part number 6V-9746.
I try to not exceed 180 degrees hydraulic temp when mulching even if I have to stop and wait for it to cool down. I also assumed it was just excessive heat, but it seems that others are using this machine at higher temps without having this problem. I'm using Cat o-rings.
I'll need to do some disassembly to get to that tube, but there must be a defect where that o-ring seats. I'm showing that the coupler is part number 373-6970 and the o-ring is 6v-9746 which is 1.78 x 18.94mm.
Do you have a part number on that coupler that is pictured? The one I have just has a groove.
I had an asv 100 that the hi flow couplers didn’t last long when using the mulcher. I’m sure it was the heat causing the failure. The internal o rings or seals wouldn’t hold up to the heat. These weren’t rebuildable and were expensive to keep replacing. I could run the diamond mower r another attatchment without issue
You may be reading temperature at cab, or wherever temp gauge is but if there is any restriction at that connection, I would be interested if you could hold your hand on it, while mulching. The o-ring you show looks like a simple Buna type and there is a whole lot better than that, for heat.
That’s what I’m betting it is. I know on my Kubota 97–2 as far as the temperature gauge goes it doesn’t have numbers, but it’s only halfway up on the gauge when I’m mulching, but there’s no way you can touch that hydraulic fittings where it connects at the high flow manifold, even the hoses are warmer than you wanna hold onto.
Sounds like the same problem. Glad the Cat coupler has an oring that can be replaced.
Yes, the coupler is extremely hot. Next time I'll take my laser temperature sensor and check the temp at the coupler when the cap temp gauge reaches 180. What type of o-ring can withstand the highest temperature?
I haven't checked the actual temperature at the coupler yet, but I did find that the tabs on the fan shroud had broken, and the shroud was hanging down on the front side by a few inches. Most of the air flow was coming out of the back of the machine instead of through the radiator. I fixed the shroud by drilling holes in a piece of angle iron and using that across the broken tabs on one whole side of the shroud to hold it in place. It appears to be running cooler now, so maybe I won't reach those higher temps with my limited use.
You could experiment with the dimensions, or the material.
I found an assorted set of Viton (fkm?) 75A Durometer o-rings that claim to be rated at up to 440 degrees F. There's a size included that is close, so I might give those a try. The nitrile one that I'm using is only rated up to 212 degrees F if I'm looking at your chart correctly.