What to Do if Your Bobcat 331 Swing Motor is Leaking
The Bobcat 331 family of mini excavators have been around for a while, and Bobcat stopped producing them altogether in 2000. This fact might deter some prospective buyers of construction equipment, wondering if there’s enough support for parts, plus additional concerns that there’s no warranty.
But Bobcat does make a quality product. Additionally, there’s nothing like paying a whole lot less than you have to for a piece of equipment that, no matter what you paid for it, still does the same work.
The tradeoff is that the maintenance burden on older equipment gets heavier, and breakdowns — when the unit is out of service — aren’t exactly convenient.
Where is the 331’s Swing Motor and What Does It Do?
The swing motor is what makes this compact excavator traverse side to side, swiveling the cab and arm. Bobcat engineered the 331 well, but there can be a lot of wear from normal use in the areas that need the most help when it comes to sealing lubricant in and keeping dirt out.
Inevitably wear causes problems for this Bobcat excavator in the form of a motor leak, and when you develop a leak, it’s imperative to act.
How to Find the Leak
The main thing you want to do for troubleshooting your mini excavator is to clean and degrease all hydraulic oil from the area around the turntable. Age and heat, along with normal operating conditions, cause seals and fittings to loosen up, fail, and begin leaking.
Since the “house” is designed to swivel freely in both directions, and all of the hydraulic system joysticks and controls are in the house, but several motors are in the carriage, the point where all those hydraulic lines meet and get distributed is mission-critical.
Lubrication is really important. Everything comes together at the swing drive, and when any one of those fittings, o-rings, or seals comes loose or wears out, it’s going to leak.
In order to track the leak down, you’re going to want to remove the floor panel (where your feet rest) and from underneath, also remove the skid plate that spans the full width of the undercarriage. Once you remove these two panels, you’ll be able to thoroughly diagnose what’s going on.
The trouble could be anything from a loose-fitting to a failed main seal on your swing motor, so be thorough in your inspection.
What to Do About the Leak
Obviously, if a fitting just needs to be tightened, and that fixes the problem, you’re on your way. It’s a good idea to run the machine for a while before you reinstall any of those access panels, though, to make sure you solved the problem.
Observe all of the hoses, fittings, and seals with a flashlight to see if the leak has stopped. If you’re good to go, simply top up your hydraulic fluid and reassemble your 331’s access panels.
However, if the swing motor is leaking from its main seal, it’s time to pull it from the machine for replacement.
You might be thinking about calling your Bobcat dealer or an equipment repair specialist right now or even checking the online forums for more information, but you may not have to. Rebuilt, Remanufactured, or Brand New?
Many people probably think it’s best to buy remanufactured or rebuilt parts for their excavator, skid steer, tractor, and more, whether we’re talking Bobcat, Hitachi, Kubota, or whatever’s sitting there leaking in your yard or equipment shed.
The Bobcat 331 is a great example of an older machine, and maybe you’re thinking the best way to keep it cheap is to buy remanufactured parts.
Not so fast.
Mini Final Drives can get you a brand-new aftermarket hydraulic motor cheaper than you can get one rebuilt or remanufactured. Additionally, there’s no core charge. Call us today and find out for yourself how much better your equipment runs with all new parts. 
