Should I invest in a new Exhaust Manifold?

[Simoniz]

I pulled the exhaust manifold off my boat today (Merc 3.0l) as the rear end cap looked really badly rusted and I think there has been some water seepage there.

Although there was some heavy rust, the underlying metal seems to be sound although I obviously cant see inside the water jacket.

One of the bolts which holds the elbow to the manifold has rusted in and does not have enough head to turn so, if I re use the manifold and elbow, it will have to be drilled out.

Boat is 9 years old and has spent approx 4 years being used in the sea (whether flushed with fresh water after use, I dont know) then 3 years kept in the sea and is now in fresh water.

Theres no sign of any perforation between the water jacket and the gas passages yet but I wonder if its time for a bit of preventative maintenance before it does happen and damage / ruin the engine?

 

[Bondo]

Re: Should I invest in a new Exhaust Manifold?

Boat is 9 years old and has spent approx 4 years being used in the sea (whether flushed with fresh water after use, I dont know) then 3 years kept in the sea and is now in fresh water.

Theres no sign of any perforation between the water jacket and the gas passages yet but I wonder if its time for a bit of preventative maintenance before it does happen and damage / ruin the engine?

Ayuh,... After 7 years in saltwater,.... I wouldn't put it back on...

 

[cruisewave]

Re: Should I invest in a new Exhaust Manifold?

Absolutely!!!!! Most of the time exhaust manifolds and risers last for about
4-6 years. The boat is 9 years old I would say its about time to replace.
Preventative maintenance is key to replacing your engine.

 

[tom_eastern_nc]

Re: Should I invest in a new Exhaust Manifold?

Found a small leak in mine after removing engine and outdrive. found a perfect freshwater unit used for $30 Seems a small investment to stop the possibility of exhaust gas or water leaking in. Be sure a good flapper valve in place and replace seal ...

Cool water + hot exhaust manifold & heads =

 

[Gary H NC]

Re: Should I invest in a new Exhaust Manifold?

I would not risk a used one...Go new and know its good for another 6 or 7 years or so...

http://bpi.ebasicpower.com/mm5/apps...Exhaust Components&MODEL=5&IMAGE=20&ITEM_ID=1

 

[zbnutcase]

Re: Should I invest in a new Exhaust Manifold?

For sure, and new elbow too. 'nutcase

 

[Simoniz]

Re: Should I invest in a new Exhaust Manifold?

Thanks for the advice - I really just needed someone to tell me to put my hand in my pocket!

Ive got the new manifold and elbow and they are covered in shiny black paint - including the gasket sealing faces.

Should I remove the paint on the gasket faces back to bare metal or doesn't it matter?

 

[Gary H NC]

Re: Should I invest in a new Exhaust Manifold?

That is black primer if they came new that way.Use a good coat of black paint over that then clean the mating surfaces with some acetone to remove the paint or primer down to bare metal.

 

[Simoniz]

Re: Should I invest in a new Exhaust Manifold?

Well, its quite hard shiny black paint, not really like primer.

But Ill take it off the flanges before I bolt everything together, right?