I have a 2003 Bobcat T200 and the other day I noticed that it had a very slow drip under the belly pan of hydraulic oil. I needed to work the machine that day so I took fluid with me and monitored it very closely. After a few hours of working the machine I noticed that the slow drip turned into a fast pour. I shut the machine down, got it back to the garage and dug in. I noticed that the main hydraulic line that goes from the pump to the control valve had rubbed up against the A/C pump fittings and was blown. Anyway, I took great caution as to cover the fitting to the control valve as well as the pump. I also needed to remove the fuel filler hose and breather hose and also the 2.5" (correct me if i'm wrong) low pressure hydraulic line feeding the hydraulic oil filter. I drained the reservoir of any oil left as I wanted to add fresh oil at this time. My question is this... After putting everything back together, the leak has stopped and I have noticed at around 1850rpm the machine makes a slight whining noise. I cannot track where it is coming from as it quiets if i work the peddles or move either track. If you idle the machine down a tiny bit, the noise goes away. The machine was never run low on hydraulic oil and was topped off prior to starting back up. Does anyone have any ideas as to what can cause this? I am 100% against taking this machine to a Bobcat dealer to have it worked on for two reasons... 1 - I am not going to give my machine to someone else to work on just to get it back with an empty wallet and have it even more *** up. and 2 - I like to wrench myself so that when things go bad, I know how to fix them. Thanks for the info if you can provide any.
I really don't see anything you did that would cause a specific whine at a certain rpm. It's possible it's a new noise from some unrelated component, could also be a noise that was already there but you just never noticed until you made some repairs and would have been intentionally listening for noises after you finished the work. Aside from this, hard for us to say what would make a noise like that since we can't hear it.
That line you replaced....is it a steel line? Magnum tractors whine like crazy and its caused by vibrations set up in the steel lines under the cab. Your problem sounds exactly like it. It will run for many hours making that sound, or you can go back in and add a clamp on the line, which will both secure it and change its natural frequency. Good luck
Thanks for the replies guys, it is definitely a noise that wasn't there before. It is more than likely a vibration as it goes away with use of the hydraulics and with slower or higher rpms. I was just curious as to why. It isn't a steel line either, I mean, it has steal braiding inside but it is a rubber hydraulic line. It doesn't seem to be causing any mechanical issues as the machine still functions perfectly so I'm going to run it. Thanks guys.