1975 Mercury 20hp Model 200: can't get the lower unit off

[Gibbles]

So I have a 1975 Model 200 20hp engine that I picked up for $50, it's a slightly older twin of the engine I use on my little starcraft.

I managed to get her running only to find out it does not pump any water.

So I went down and picked up a new impeller and started the removal process of the lower unit.

I removed all of the bolts and found that I could not get the lower to drop much, so I went to my good known engine and proceeded to ensure I was doing it correctly, I had no issues dropping the other lower.

So I decided I must just be stuck a little so I started working it with a rubber hammer, after a bit I was able to get it to drop about a 1/4 inch...
So I started prying on the rear bolt to try and get more...

In the end I was able to get a flat prybar in front of the water pump and it looks like my drive shaft is clear and I may be stuck on the shift shaft as I am unable to get much space from the rear.

Looking at my other lower the shift shaft goes up into a linkage in the rear of the midsection and it has a splined male end, it does seem to have a notch that could be used to hold it in but I cannot find any signs of a screw or other in that area.

I think I can remove the mid section from the rear portion and it may show me more of the shift shaft, I'll attempt it this weekend...


Any ideas or tips to get this thing off with out doing (more) damage to the lower & midsection?

Thanks in advance.

 

[Gibbles]

Re: 1975 Mercury 20hp Model 200: can't get the lower unit off

Well today I got it off, it was the drive shaft.

I bought a can of seafoam deapcreep and bent the tube so I could spray at a 90 degree angle after inside of the lower and sprayed with the engine up side down and let it sit like that for a few hours


Then took a prybar on the rear bolt and one shoved into the lower just in front of the water pump and put my weight into it, started to slide and then POP.

Impeller is changed and it's back together, fired up and now pumps water.

 

[Crazyman1225]

Re: 1975 Mercury 20hp Model 200: can't get the lower unit off

Hope you cleaned and lubed the shaft before assembling it, so it doesn't happen again

 

[Gibbles]

Re: 1975 Mercury 20hp Model 200: can't get the lower unit off

Yeah, scraped and cleaned the shaft.

And I sprayed some seafoam up into the shaft hole letting it sit and then rinsed out with more seafoam, then inserted the shaft about 4 times and removed cleaned the shaft and rinsing the hole each time.

Finished it off with some copper based high temp antisieze when putting everything back together.


It looks like who ever had this engine running before me ran it shallow and in sand, the cooling system was mostly clean, but I found lots of sand in all of the nooks and behind the water pump.

The impeller looked melted on the bottom, and I scrubbed out the water feed tube before putting it back together.



If all goes well and if everything on the engine checks out I'll run my twins side by side on my tin boat.