VF-9 Gearbox Pump Problem

[JoBwan]

To all,
I have appx. 15 - 20 Haas machines in production. I have learned many machine repairs from everyone out there by using this site. I am new to the communication end of the forums, so please bare with me. OK, I have a '96 VF-9, started a week ago with a "Low Pressure Trans Oil" alarm (# 179). First Step- Changed the Pressure switch. I started the machine and noticed that there is no oil movement in the cooling lines. I drained the oil out of the gearbox and flushed thru each line to be sure that nothing was plugged up. Re-filled with DTE-25 oil. No change. Second Step - Changed the Pump Assy (# 93-3260B). Restarted the machine again and noticed that the oil is now fluctuating up and down in the "pick up" tube to the pump. I then primed the pump and it will pump for appx. a minute or so and then fluctuates again. I called HFO and they don't have any resolution for the problem. I feel it may be a bad pump unit. Not quite sure how to confirm. Does anyone know of any filter screens, inside the gearbox, on the pick-up tube? How is the tube mounted inside the gearbox? I really don't want to pull the spindle assy., if someone has seen these symptoms before, and can give me some insight. I am open to all suggestions. Thanks in advance. Joe

[haasfixer]

there is no screen inside the gearbox there is a screen if the machine has a trans cooler. if the pump is losing prime it could be that you have a loose hose allowing air into the system. if you replaced a magnetic old style pump with the newer style pump then you need to have a loop in the output line of the pump or it will lose prime when you shut it off. make sure the coupling on the gear pump to the motor is not loose. the pump somes off pretty easily and you can see the cheasy coupling that they have in it

[JoBwan]

Haasfixer,
You said that it has a screen, if it has a cooler. It does! Where is the screen located? I pulled the pump motor and the cheesy colored coupling is tight. Just so I'm clear with my explanation, it is losing it's prime while the spindle is running. I have a loop on the output side, as you recommended and nothing changes. I have now replaced all of the lines except the pick up to the gearbox. Thanks for your help, Joe

[haasfixer]

the screen should be inline with the pump there is a little plastic cup with a magnet and a screen in it maybe the fitting at the trans is no good i am pretty sure it is just a push loc

[JoBwan]

Haasfixer,
I finally bit the bullet and removed the spindle motor from the "Z" axis. I'll be dipped in dog doo, I found the cause of it sucking air into the line. There is a brass pickup tube from the resovior and threads into a manifold, that at first felt loose. Upon further inspection, the 1/4" NPT threaded end had actually broken inside of the manifold. It was not completely broken in two and that made it very challenging to diagnose or even find. Then as I was trying to remove the tube, "You guessed it", the threaded end broke completely off -- inside the manifold. I was able to remove the resovoir and brackets to gain access to the broken threads and an easy-out did the trick. Reassembled and wah-lahh. the pump is going again. Thanks for your posts. I hope someone else out there will save some time from my problem experience. This thread can be closed or archived. Thanks again, JoBwan