1998 Mercury 125hp ELPTO - Sealant between exhaust manifold and water pump

badcrc

Cadet
Joined
May 3, 2017
Messages
11
In trying to replace swivel pin on my 125 Merc I've had a nightmare situation so far with several bolts snapping off and nothing I could do to prevent it. I drilled them out and retapped the holes. As a last step I thought I'd replace the impeller while I was in there thinking surely that would go easy since I just paid a shop to replace the impeller and seals 3-4 years ago and have only ran the motor in fresh water since I got it 5 years ago. The first bolt I tried on the water pump housing snapped off when I (very gently) tried to loosen it. Needless to say the corrosion of the bolts and the gaskets looked more like 20 years worth, rather than 3-4 when the shop supposedly did the work. Also I would imagine any decent shop would have put in new bolts with grease.

My question however is about the sealant to use between the water pump and the exhaust tube. I've read various posts about RV sealant and other stuff but most are old. When I took it apart there was a very thick bead of black sealant in there, at least 1/2" thick. Can anyone recommend a specific brand to use and how much to use?

Also, my plan was just to replace the impeller and gaskets. I'm scared if I dig into the water pump at least one of those six bolts might snap off and I have to drill and tap more holes. Should I take that apart to replace the seals or not? There was no issue with the water pump, and I will probably be selling the boat long before the water pump fails.
 

badcrc

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Joined
May 3, 2017
Messages
11
No Title

You guys think this looks like 3-4 year old freshwater corrosion? In the last picture with the water pump housing, it's the bottom right corner bolt that snapped off.
 

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