Drive Oil Reseivor overflowing
 

I have bravo one's that has been upgraded by imco and have the imco lowers on the drives. The lower on the port engine blew up a month ago. I had it rebuilt and it blew up again in about 3 hours. The shop said the case was bad so they got a new case and put everything back together. I just ran the boat today for the first time and the drive oil is overflowing from the reseivor when you run it fairly hard. This also happend each time before the drive blew up before. Each time the shaft broke by the pinion bearing and the bearing & shaft showed signs of heat. Any help would be appreciated.

You've got air in the drive where there is s'posed to be lube. The pocket of air expands with heat and forces lube back up into the reservoir.

Trim it down to neutral and drain it with the cap off the reservoir and the plugs out of the drive.

Using a lube pump, attach it to the bottom drain plug and pump lube in it till it comes out the top plug. Replace the plug and keep pumping till the reservoir is full to the line. Replace the reservoir cap and get ready to pop the bottom drain back in. Remove the pump fitting from the outdrive and stick the plug back in real quick and tighten it back up. Problem should be solved. (at least the lube level rising).

Use only hi-perf lube (from merc or redline or royal purple or similar)

one other possibility
 

Acquaintance of mine runs a merc #3 or 4 and the rear seal was rubbing the prop - at high speeds water was being forced INTO the lower unit - water is a ****ty high preasure lube - oil fill was overflowing.

seal was replaced and forward side of prop machined away from seal - no more problem.

Just a thought!!!
MAV

yup, check for water being forced in by bad seal, or o ring between the drive and gimbal in my case

The gear oil is clean - no water at all. It seems that the oil is heating up.

Oil doesn't expand appreciably with heat. A tiny bit, yes, but not much. Air, however, expands dramatically with heat.

I'm still thinking air pocket.

i had the imco extream and was runing some synthetic in it ,it would foam and rise when ran hard .went back the the merc fluid ,did not happen again. imco said the never had a prob runing the merc hiper lube.i now run the b maxes and run amsoil h4 lube and it foams a little but nat bad, someone told me you might be geting a little water in it and its boiling the water in it when it gets hot.

Check your reservoir cap. Make sure it isn't cracked and the rubber gasket is in place. Air leak will cause the lube to foam and overflow.