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Foam in outdrive oil

rms59

New member
This is a 1987 OMC cobra stern drive that was completely rebuilt 4 years ago. Last outing I noticed some oil in the driveway under the lower unit so I pulled it out and separated the upper and lower halves. When I pressure tested the lower half there were leaks at the shift rod so I put in new O rings and gaskets there and new O rings on the intermediate shaft housing too. Tested again and it passed at 18lbs pressure. Vacuum test was OK too. Then I assembled the two halves and pressure and vacuum tested again and it all passed 18lbs for 3 minutes.

After refilling the drive with gear lube (OMC recommended) I notice the gear oil had some foaming after testing with dog ears for 2 minutes. What could cause the foaming? Taking a sample of it and letting lit sit for an hour it settled out and doesnt have any water.

Just foam.

Thanks
Richard
 
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