1969 Merc 350 lower unit off but need ideas!

[lifeandliberty]

well I got the lower unit off and removed the water pump housing. The impeller is looks fine. so here's my problem Drive shaft and impeller as you can see from the pics the drive shaft is pitted really bad and when I spin it the key does not catch the impeller. so here is what I'm thinking. J.B. weld on the key area and sand or cut area for the key to catch. Just wonder if this would work or if anyone has a better idea!

 

[NathanY]

Re: 1969 Merc 350 lower unit off but need ideas!

Have you tried a new key? They are cheap and readily available.

 

[jim phillips]

Re: 1969 Merc 350 lower unit off but need ideas!

I am with nathan ...get a new key and take it from there You should be able to clean that up a bit with emmory cloth. Let us know how you make out

 

[Chinewalker]

Re: 1969 Merc 350 lower unit off but need ideas!

I think the original drive method was a pin, so you might benefit from making a larger pin, or perhaps finding a new-style key with the driveshaft side flat and the impeller side having a bump to go into the groove in the impeller hub.<br /><br />If you stick with a pin, try using a larger diameter stock, preferably in brass or stainless steel. As long as it stays in there and firmly engages the impeller you'll be fine.<br /><br />How is the sealing surface of the driveshaft below the pump base? That's where they tend to rust a lot, enough so that it's difficult to keep oil in the unit. I took my driveshaft out and filled the pits with JB-Weld, then sanded it all down flush - no water in there now after 3-months of use!<br /><br />- Scott

 

[ratt1966]

Re: 1969 Merc 350 lower unit off but need ideas!

I had the same problem with mine took shaft out and jb welded the pits and also replaced the key for the impeller works great now. good luck

 

[lifeandliberty]

Re: 1969 Merc 350 lower unit off but need ideas!

I think I'll go with the larger pin or maybe half-moon key whichever works. The drive shaft is pitted around the base of the water pump so I'll try the J.B. weld there and sand it down like suggested. I really appreciate all the help. I'am back at work now and can only tinker with it in the late evenings. Having a blast fixing my first boat motor. Next step is gasket replacement on the powerhead. I'm sure you will be hearing from me. Until next time, Fair winds and Following seas!