Originally Posted by
Mike K
I'm new to this forum and couldn't believe the timing of this thread.
I just went through this filling process and it really sucked.
I noticed the pressure was a little low and hooked up an unregulated nitrogen bottle. The valve was very tight and when it finally let loose, I overfilled it by about 100#. It didn't take long at all to let too much in. Being a compulsive type I tried to bleed it down a little.
Bad idea! The only thing that came out was hydraulic oil. I saw the error of my ways and decided that a little extra pressure wasn't so bad after all and proceeded to disconnect the nitrogen line.
Oil everywhere! The stupid Schrader valve had failed! I tried frantically to cap it but there was no way I could overcome that kind of pressure. So I watched the oil bleed out until it was almost gone, at which point a pink fog started spewing out.
Then, as the pressure dropped to 400# the head started dropping!! Fortunately the spindle was over an empty space between a vise and rotary table. It actually slowed down near the bottom of the travel and came to a gentle stop that didn't damage anything but the bracket that the programmable coolant nozzle mounts to. The spindle didn't touch anything. Very lucky!
So then I had to refill the bottle with 2 quarts of DTE 25 oil, replace the Schrader valve and recharge the system.
I did all that, and wouldn't you know, as I was removing the nitrogen line oil started coming out again! The new Schrader valve failed too! This time I hadn't yet fully removed the fitting so I tightened it back up and left it there. Still hooked up to the refill bottle.
So, if I had it to do over again, here are the things I would do differently:
1. Make sure the valve on the fill bottle can be cracked open easily. It would then be easy to avoid over filling.
2. Bring the head down to a block of wood so it doesn't have anywhere to go if you unexpectedly lose pressure.
3. If I ever bleed it down again, I will install a high pressure needle valve between the Schrader valve and the system. With this, I won't be depending on a tire valve to hold 750# of pressure. It will make filling a lot easier to control as well.
Good luck!