We are experiencing a chronic problem of gearbox oil leakage throught the top lip seal (part no 115 on attached drawing) of Sundyne Model LMV 312 machines. In both recent cases the gearboxes were newly refurbished units supplied directy from Sundyne France as part of a major equipment overhaul. Our investigation thus far has not come up with cause for this oil leakage. The seal removed is in very good condition and the mating shaft surface shows no signs of damage. We have chack axial position of the flexible coupling and alignment to driver with no indication of a problem. Has anyone in the forum had similar experience with LMV 311 or 312 machines?

This message has been edited. Last edited by: Aramco,

I have only seen leakage with seal damage. Check that the breather is in place and unplugged.
Regards
Joe Mc Cormack

In both cases the breather was brand new and unplugged.

Mr VandenBroek,

What type of driver you have been using for this sundyne Motor or Turbine driven?
Is there any possibility of developing low pressure zone underneath or near by seal area of your driver to draw oil outfrom gear box?
How do you check the seal is leaking from the seal after the driver assembly.Assume there is leak of port to detect(open to atmosphere),
I have seen some operators used to plug that hole with solid plug which invites more trouble ?
would like to know in your case

A number of thoughts come to mind:

The seal may be installed backwards.

There is excessive pressure inside the unit.

The machined surface that the seal rides on may have a texture (called the "lead") that pumps the oil out. Essentially this is a turned or ground surface where the marks spirals outward relative to the seal rotation. One way to check for lead is to loosely loop thread over the shaft in a single loop with a weight hanging on the bottom. Then check which direction this loop travels when the shaft is turning. It shouldn't move in either axial direction.

If possible replace existing lip seal with ISOMag seals. I suggested it to Sundyne about 7 years ago. I replaced it on all my LMV311 pumps.