1985 Mercury 115 tower of power

[Chevy5757]

I am going to look at a boat that has a 1985 mercury 115. its original to the boat. owner says its getting water in the number 3 cylinder. What are the possible causes of water in number 3? I can take my compression tester, bore scope camera and leakdown test equipment with me to evaluate. What should I be looking for? Can this be simply a gasket failure or am I looking for a cracked block or head?

 

[jimmbo]

Most likely cause is a problem with a Exhaust Water Jacket Cover/Gasket(12 & 13) inside the Exhaust Housing in the Port Side of the Engine. 16 & 17 might also be involved
A Crack in the Block is another.
You will likely see a very clean Piston Crown when you use the Bore Scope

 

[Chevy5757]

Most likely cause is a problem with a Exhaust Water Jacket Cover/Gasket(12 & 13) inside the Exhaust Housing in the Port Side of the Engine. 16 & 17 might also be involved
A Crack in the Block is another.
You will likely see a very clean Piston Crown when you use the Bore Scope
View attachment 385880

Thanks for the info and the exploded views. Do you have the next page that identifies the detail numbers?

 

[Chevy5757]

Thanks for the info and the exploded views. Do you have the next page that identifies the detail numbers?

are these online somewhere?

 

[racerone]

There is no head gasket that can leak.-----Likely an issue with exhaust covers.

 

[roscoe]

Parts diagrams are on mercruiserparts.com
Or Crowley marine web site.

 

[Faztbullet]

Get it cheap as hard to find people to work on these

 

[brodmann]

That is not a terribly difficult project. Might find some good cleaning that needs to be done, but it should be a quick if parts are readily available. Those were some great motors! I looked for a long time for one for a project that would have looked perfect with one of those motors on it. Good find.

 

[Chris1956]

Part #14 and #17 can rot out allowing water into any cylinder. They can also warp, and make it hard for them to seal. The repair is a real PIA, as you realistically need to pull the powerhead, true up and/or replace the parts and bolt everything up, and then it maybe still leaks. I would price new parts #14 and #17 to make sure you can get 'em.

Walking away would be a better alternative.

 

[racerone]

Parts #12 and #17 might well be the issue.----These are great running engines if maintained properly.-----If it has had water sitting on bearings for a long time there could be issues with bearings.-----Depends on your level of ambition with these engines.----And a 1985 could also require huge amount of work.------What is the asking price?----Pay no more than $750 I think.