Manifold to head question

[shaun77]

I have a 2011 4.3l dry joint merc I'm replacing manifolds and risers on. As I was cleaning the head surface I found what looked like a small area of raised corrosion on the outside of the head. I filed it down and can lay a straight edge flush across it but my question is does the head surface need to be perfectly flat, like machined flat for the manifold and gasket to seal?

 

[alldodge]

I have a 2011 4.3l dry joint merc I'm replacing manifolds and risers on. As I was cleaning the head surface I found what looked like a small area of raised corrosion on the outside of the head. I filed it down and can lay a straight edge flush across it but my question is does the head surface need to be perfectly flat, like machined flat for the manifold and gasket to seal?

Yes, it needs to be flat within .010 to .015

 

[shaun77]

Ok. Does that mean the head would have to be removed or can it be machined and measured in the boat? I only ask because these were factory manifolds and if the engine has to be torn down first before I can replace everything I am wondering if this is a warranty issue or not.

 

[Bondo]

Ok. Does that mean the head would have to be removed or can it be machined and measured in the boat? I only ask because these were factory manifolds and if the engine has to be torn down first before I can replace everything I am wondering if this is a warranty issue or not.

Ayuh,.... I'm wonderin' why ya gotta do all this work on such a New boat,.....

What's wrong with the original manifolds,..??

Were you able to get a .010" feeler gage under yer straight edge,..??

 

[shaun77]

No Title

Well I'm in all saltwater for one. I was running hotter than usual at high speeds so pulled everything to check. The risers needed to go and I was told the manifolds looked okay but I did have some casting coming off and may only get another year or so, so I opted to just change it all at once. Heres what I'm seeing tho...

 

[Fishermark]

Well I'm in all saltwater for one. ... The risers needed to go ...

I too run exclusively in salt water and am aware of the corrosion problems that salt water presents. BUT... I am amazed you only got two years from a dry exhaust system. I find it hard to believe that your manifolds are bad.

Of course, I am also surprised at the corrosion you have on your heads there. It looks like you maybe have had an issue with salt water dripping onto your manifold area - or a regular splashing there? The good news is there is no water issue there. If it were mine I would simply do as you have done and file down the area. Put a good gasket on and run it. Whether you install new manifolds is up to you... if you think they are bad, then go for it. But on the head, I think you are okay.

 

[Scott Danforth]

to me it looks like gasket material still stuck to the head port mating surface.

 

[Bondo]

to me it looks like gasket material still stuck to the head port mating surface.

Ayuh,..... Faarrr from clean enough to reassemble,.....