I recently (last Thursday) was taking the boar from the mooring to the marina (Less than 200 yards) to have her hauled out and replace the cutlass bearing. The engine started normally as usual, I let the glow plugs burn about 10 seconds longer than usual since it was pretty could out. Like I said, the engine started right up and it was idling normally for about 10 minutes. As I engaged the forward gear and throttled up, the engine started to race far faster than ever did run, completely out of control. I throttled down to no avail, I turned off the ignition and pulled the kill lever to no avail, obviously and thankfully the prop was turning so fast that I am sure we were cavitating so much that we were not doing any headway, even thoug I can see some prop wash. Finally I engaged the reverse and that killed the engine, (and the transmission maybe), also as all of this was going on, loads of black and white smoke were coming out of the exhaust pipe. After a few minutes, I was able to start the engine again with similar results, so I left it alone. Also as I look down the companionway, I can see a puddle of black oil on the floor of the cabin. As I took off the engine compartment cover I could see that the oil came off the breather tube of the Universal M-18 Diesel. After much thinking about it, I believe that this episode may have something to do with the engine speed governor and that all that smoke coming off the exhaust was due to all the oil ingested by the engine coming off the breather tube, maybe wrong , but I certainly hope so, and not some other major catastrophic ocurrence.Any suggestions as far as type of engine to repower if needed, or if not where should I start my investigation. She is on the hard right now, so I got a bit of time till she is back on the water and I am able to start the engine again for trobleshooting. Appreciate all comments.Jaime PandoS/V Southern Cross