I have another question related to the drive motor seal replacement on my 743. Having sorted out the required seals and o-ring, I was talking to the service department mechanic at my closest bobcat branch and he mentioned that blown seals are often related to clogged case drain filters causing excessive pressure. I traced the case drain lines for the drive motors on my 743 and I couldn't see anything looking like a case drain filter. Looking at the parts manual it would appear there aren't any on this model. The mechanic's suggestion was to run the bobcat with the case drain hoses disconnected and see if one motor pumped more fluid out of the case drain than the other. Does this sound reasonable? Thanks.
Help Support SkidSteer Forum:
The newer machines have case drain filters, the 743 does not.
Depending on when your machine was made, it's between 26-36 years old. It may just be it's time for a seal to go.
There is always a chance the case drian line has been plugged, but i'd highly doubt it.
Depending on when your machine was made, it's between 26-36 years old. It may just be it's time for a seal to go.
There is always a chance the case drian line has been plugged, but i'd highly doubt it.
Thanks again, Tazza. Tomorrow will tell, I have the parts so it's time to get dirty.
All done. I couldn't see anything visibly wrong with the existing seals but the ol' 743 doesn't appear to be chewing through hydraulic fluid like it used to, based on initial testing. It'll take a good solid run to be sure though.
Can these filters be easily installed on your machine? Couldn't you just add filters to the case drain return lines? Or is it more of a hydraulic plumbing a problem?
I was considering the same thing. I'd have to get a fitter to make up some hoses but I'm pretty sure you could add an inline filter, provided it doesn't do something the 743 wasn't designed for.
You can add one, but why bother? they ran them for years without the need for these filters.
When a motor spits its guts out, a case drain filter won't save your pump
Damn good point. Was just thinking that a little more filtration might help prolong it just a little longer.You can add one, but why bother? they ran them for years without the need for these filters.
When a motor spits its guts out, a case drain filter won't save your pump
Extra filtration can't hurt, i wonder why the newer machines added them and not the old ones? the innards of the pumps and motors are the same, old and new.
If I absolutely had to bet, I would say that it would give you a heads up to rebuild the pumps / motors, before they went completely bad & "trashed" the entire system. When I serviced our first 863's, they both had small amounts of rubber O-rings / seals in them. Obviously, they came from each of the travel motors. The amount of trash in there was not significant enough for us to rebuild / repair anything at that time. But If it were worse / had far more trash in there, then we might could have concluded that it was time to rebuild them before it caused all kinds of other problems; like killing a good pump. So, maybe they serve the same purpose as cutting open other fluid filters, for just a little more information.
Thanks for the comments. I'll probably add case drain filters when time and funds allow, just as a safety precaution.
