Just put a new hydraulic oil cooler on my machine, what do I have to do about bleeding the pump? Looking at it I don't really think draining the tank would have necessarily drained the pump, but don't want to take any chances. How would you go about bleeding the system, especially the pump?
Off the pump(s) should be a hose going to a spin on filter. This would be case drain. Loosen hose and hold down over bucket till fluid runs. It's gonna be a while. Or simply flood the pump case through that fitting. Resecure hose. Start and let her run at idle for a couple minutes. Slowly exercise some cylinder functions, not to end of travel. Re check oil level. Let her run at idle for a bit again. Make sure your oil isn't foaming. If it has, let her sit for an hour and go back at it. Listen for howling, gotta use your own judgement. Some is good ,real loud with vibration is bad. Good luck and hope this helps
These old dogs didn't have a case drain filter. I seem to recall there was a bleeder that looked like a brake system bleeder on the front half of the pump. Open that up and watch for oil to come out. It will bubble for a long time. Once it is running clear tighten it up and start the engine. Let it run for a few minutes and then shut down and bleed it again. Do this a couple of times and then raise and lower the boom at mid engine speed. Shut down and check your hydraulic oil level. There are some other plugs on the pump that will let it bleed faster but I don't recall exactly which are which so if you try one or two of them its at your own risk.
I'll take a look for that fitting. I know there's a plug on top of the pump, about 3/4npt size with hex on the outside and 1/2 square in the inside (looks like it has a shoulder, don't think it's actually pipe thread). There's also a return hose from the top of the pump back to the tank. The fitting for this hose has a small plug on top, like 1/4 inch diameter.
Looked, nothing that looks like a brake bleeder. A lot of the fittings for hoses have the little square-head plugs though.
The little square headed pipe plugs can be used to bleed air. They were 1/8" BSP. I recall the hose at the back and on top of the pump as well but only remember it on the PC300 and PC400 machines. It has been a long time since I've put my hands on a Dash 3 and even longer since working on a PC200 of any series. The thing that most people make a mistake on is that bleeding the output lines from the pump to the valve doesn't actually get all the air out of the pump case. It only bleeds the areas between the piston and barrel assembly.
Thanks John. You're right, they are 1/8". Cracked one going to the valve and it oozed oil. Cracked the one on the return and heard air hiss out, but oil level in the tank is too low to have oil come out that plug (oil is in the window but machine isn't on level ground and return line is above the top of the pump). The big plug on top of the pump doesn't want to budge. I popped a rib out last week and am a bit short on torque right now. I can try a cheater, but am open to advice. If the pump isn't completely bled out and I start and idle the machine will I damage the pump?
I wouldn't take out the big plug. Top off the tank and just be easy for some minutes. If you hear any funny noise just shut it down and start bleeding air again. The oil level in the pump needs to be a little over the piston and barrel assemblies is all when just starting up. The internal motion will help push the air out but don't start it up wide open and through a big load on right away.
Thanks again. The big plug makes me nervous. It's probably just a plug, but we've all unscrewed things that look like a plug and turn out to have 15 springs and 87 check valves underneath. Sproing!