Lower unit stuck issue

[PISTONESAL]

I dropped my lower unit on a 2000 mariner/Mercury 75HP outboard and it was a bear. Really had to hit hard to get it to come down but got it off. What causes this and how do I got about installing so it's not so difficult? I am looking to replace pump and other seals and was hoping if anybody can suggest how to avoid this from happening in the future as I am not sure how difficult it's going to be to get it back on? Also, previous owners did not hacking to get it off by prying with a screwdriver so the joint points between lower and midsection has some gaps from the screwdrivers. Do I need to put some gasket seal on the edges? Any help would be greatly appreciated it. Thanks again. I have looked and have not been able to find to much info on this..

 

[GA_Boater]

Used in salt, Piston? That often makes a fairly easy job tough.

When you put it together, put some marine grease on the shift splines and the driveshaft splines after cleaning the splines. Not too much on the driveshaft and only on the splines, not the top.

No need to seal the screwdriver gouges. The lower unit has no gaskets or sealer between the midsection. That gets filled with water and can't be sealed anyway.

 

[PISTONESAL]

Thanks for the reply. I really appreciate it. I am not a super motor mechanic but I am very handy and can do a lot especially to save $$ Yes, used in salt water. Don't know what you meant by piston? I noticed it sticking at the alignment/dowel pins. Really had to hit it hard to get it off. Will I have to go through this everytime I want to replace the water pump? There is no way for me to avoid it sticking? If I had to hit it hard to get it off, putting hard will I have to hit it hard also? If so it worries me because how will I know if the shaft or shift shaft are not aligned correctly and by hitting it can cause other damage? Also, there is a chamber'space that drops inside in the middle of the lower unit behind pmup. I have seen video and also notice there was a silicone sealer applied around that area. Do i need to do that? See this video (https://www.youtube.com/watch?v=OuilMAOMpgQ) and its around minute 15:40. He applies that silicone and then some other stuff i dont know what it is around the stud bolts. What is that stuff? anti seize? Should I use it and put some around the alignment pins also? Your thought or suggestions? Again, I appreciate the help.

 

[GA_Boater]

Piston is part of your username, Pistonseal. :smile:

I don't why he was putting sealer where he did. He was working on an Optmax if that makes any difference.

The rest of the time he used marine grease on the studs, etc. That's to slow down corrosion for later removal.

From our Mercury outboard stickies written by merc850 - http://forums.iboats.com/forum/engi...od-of-shift-shaft-setup-for-mercury-outboards

 

[PISTONESAL]

oh ok Thanks for the forum link. That will help. So that empty chamber does not have to be sealed? Water goes down in there? It looks pretty dry. I don't know what the optimax would call for but I just want to make sure I do this right the 1st time..No other tips when ding this reseal job? Trying to get as much info as possible before moving forward. If you know of a better video or literature, let me know. I have the service manual but its not that detailed as far as step by step.. thanks again