Exhaust header leaking.

[ulster1]

Just back from starting the motors and discovered that the port motor exhaust header on the starboard side is leaking.
Twin 4.3 efi, 2001, engine serial # omo 25934.
Am planning to go down tomorrow to remove the header for a good inspection but it looks like it is leaking from the stern section and in looking with a mirror it seems to have rusted through? Anyone have a comment on this? I was surprised that it would have rusted, I am fussy with winterizing so I do not feel it has cracked.
If everything checks out OK would you consider brazing it up and just reinstalling it or should I replace it.
Any experts out there if so could you provide me with the gasket and manifold #.

Thanks.

 

[Don S]

Re: Exhaust header leaking.

They are called manifolds on boats, not headers. If it's rusted through, it's junk.

Your 0M025934 serial number is for a 496 engine, not a 4.3.

 

[ulster1]

Re: Exhaust header leaking.

They are called manifolds on boats, not headers. If it's rusted through, it's junk.

Your 0M025934 serial number is for a 496 engine, not a 4.3.

---------------------------------------------------------------------------------
Thanks Don I screwed up on the serial # it is omo35934 NOT omo29534 as per previous post.

Is this a common problem with a fresh water motor? Should I be worried about the other 3 Manifolds? or just replace them when they leak.

I will order a new one.

Ed

 

[Don S]

Re: Exhaust header leaking.

Rusting through an exhaust manifold in a fresh water boat is not common at all. Especially on one as new as yours.

I would suggest you find exactly what the problem is before thinking about buying any parts.

 

[ulster1]

Re: Exhaust header leaking.

Rusting through an exhaust manifold in a fresh water boat is not common at all. Especially on one as new as yours.

I would suggest you find exactly what the problem is before thinking about buying any parts.

Update. Removed the manifold and sure enough it was cracked now I am pi-----d because I am so careful re winterizing. I ordered a new manifold and installed and now back in the water running good. However I have to figure out what happened?? so I took a ball peen hammer and hit the manifold on the crack and opened it up to see inside. What I found was a lot of shale/scale that had caused a blockage and would not let the water drain during winterizing.
So now I am thinking how do I stop this from happening again or to the other 3 manifolds.
If I remove the plugs on the top of the manifold near the risers and back flush with a garden hose and the drain plug out will this flush the system.
Would appreciate feedback if anyone else has had this problem.
The aftermarket manifold is a much better design than the mercruiser it has drain plugs in several locations not just the one where the cooling hose connects.

 

[ulster1]

Re: Exhaust header leaking.


Just thought I would add pic's to make it easier for folks to understand.

 

[Don S]

Re: Exhaust header leaking.

When you drained the manifold, did you use clean the drain plug hole out with a screw or nail or something to make sure the water drained out?

 

[ulster1]

Re: Exhaust header leaking.

Yes I have a special piece of wire for to do this and I always make sure I get water out.
The only other thing I can think of is, --- I keep the bow 5" higher than the stern during winter storage could this be a problem.

 

[Don S]

Re: Exhaust header leaking.

Might, but it doesn't sound like very much. You are supposed to have the engine level when draining. Put the bow up when you are all done.

 

[ulster1]

Re: Exhaust header leaking.

What do you think about flushing the manifolds with a garden hose from the top of the manifold where the 2 plugs are just in front and behind the riser?? If I flush these out it hopefully will flush out the scale? I have been doing the winterizing now for the past 10 years with no problems until this year same cradle etc.
I think next winter I will put antifreeze through and drain it just to be sure.

 

[Bondo]

Re: Exhaust header leaking.

What do you think about flushing the manifolds with a garden hose from the top of the manifold where the 2 plugs are just in front and behind the riser?? If I flush these out it hopefully will flush out the scale? I have been doing the winterizing now for the past 10 years with no problems until this year same cradle etc.
I think next winter I will put antifreeze through and drain it just to be sure.

Ayuh,.... I poke, 'n prod my drain holes with a 4" deckscrew....

Yer plan for flushin' is pretty extreme,...

Just pull the drain plugs, 'n Run the boat,...

Plenty of water oughta flush out any crud.... just don't get ahead of yer bilge pumps....