merc Mark 75

[motoscott909]

I posted this over at fiberglassics, so I figured I would post it here as well.

This past weekend I was surfing the local craigslist and I found an ad that just said “old mercury motors”. I texted the seller and he replied that he had two really old motors for sale. He said that one was white and one was black. He told me that one of them was 75 hp. It was obvious he had no idea what the motors were and I didn’t really want to ask a million questions over the phone, so we set up a time to go look at them the next day. They were only about 15 minutes from my house which was nice.
I got there and was sort of amazed to find a black Mark 75 60hp and a white 600el. The guy that was selling them had found them in an old semi trailer full of junk that the previous owner of his farm had left. He had mentioned that the semi trailer had not been opened up since around 1970, so they have been sitting for a very long time. The white 600 was completely seized, but the Mark 75 turns freely. I ended up buying both for $80. They also came with a large box of parts including two brass Michigan wheel props. I’ve been looking for a dock-buster for some time, so I was excited to get these for such a low price.
The lower units on both motors were completely apart and the guts are sitting in a separate box. The Mark 75 lower unit is cracked, which is why I assume the previous owner stopped running it. I think I should be able to weld it. The white lower unit is not cracked, but the scag is completely broken off the bottom. Does anyone have a blow-up of the lower units showing how the waterpump etc. go back together? These seem a bit different than anything I have ever worked on. Also , there are some rubber “duckbills” in the box, that I assume have something to do with the water pump, but not sure exactly what?
Im sure I will have a ton of questions over the next few weeks when I try to get it back running. I was reading that setting the timing on these is tricky, so im sure I will need help with that. Im also searching for controls as the guy couldn’t find them in the semi trailer.

Any other advice you guys have about these?

[frankr]

Will this help??
http://s19.postimg.org/5133y9coj/Mark_75_gearcase.jpg

About the duckbills…would they by any chance be those "Automatic Boat Sinkers", er..I mean "Boat Bailers"? Will they fit the boat’s drain plug?

[motoscott909]

Thanks for the diagram.

I believe that the "duckbill" is part #33 in the diagram. I think it is some sort of check-valve for when the engine turns backwards, since the impellor also has to turn in reverse, but I could be wrong.

[frankr]

Sorry, shows how much I know about Dockbusters.

[dave-bernard]

you are correct.

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