Bravo drive - oil loss and foaming

[mghunter]

I had my port Bravo drive (2003 vintage) rebuilt a few months ago after I almost lost it after the transom gimbal ring cracked (all new seal, bearing etc)

Since then I'm losing oil (I have a lube monitor) but is seems more when it standing on the mooring, not when it going. No tell, tale oil smell or droplets around the transom in the water, dry bilge, etc.

It has dropped to the lube monitor add oil level in around 2 months.

A few other weird things are happening, namely

a) oil level rises around 1 cm when running, and then drops back when cold
b) a small amount of foaming on top of the oil after a run.

The mechanic who rebuilt it suspects a air leak somewhere (to explain the rise in level and foaming) , but has pulled the boat and pressure tested the drive etc and cannot see where or why it is losing oil.

It did not help that he did not first clean out the lube monitor which had some water in it from the above damage, but he fixed that.

No vibration in the drive / propeller, no fishing line in seals etc

My starboard Bravo drive does not do the same, but it was not rebuilt. It does also lose a bit of oil, but only a small drop in level compared to the port one.

Prior to rebuild port drive did not lose oil and I only needed to top up once in a while (12 months).

Any suggestions ?