Condensate in manifolds?

[william.frank]

Hi All,
Nail biting question…

I decided to inspect the exhaust system on a 2002 5.0 mercruiser I just bought.
I got the riser off (wet joint), and to my surprise it was in much better condition than I expected. There is some minor surface rust in the water way but nothing major, no rusty flakes coming off etc. Same in the manifold - the water ways are pretty ok.
HOWEVER - at the bottom of the manifold I found a small pool of very rusty liquid in two of the 4 indents at the bottom. With a thick rusty cover/film/layer on top of the liquid. There were also tiny liquid bubbles on the side of the gas chamber.
there are no rust marks around any gasket areas, or general rust on the sides, spacer or risers and no way that the manifold has a fully rusted through wall to lead the water in. Otherwise walls look “nicely covered with a bit of sooth”.
Also - the boat is out of the water since Nov ‘19 ~18 months, to the best of my knowledge it has been started once in early April by another buyer, I would assume on a hose, but no way of knowing. The manifolds were empty, not sure if they would go through the trouble of draining them after they tested or if they run it for just a bit without any water…
Can this be just condensation? It’s the north east, we get wild temp swings between days and nights, especially lately…
Not sure what to do - replacing perfectly looking manifolds is a costly decision…

 

[Scott Danforth]

Condensation is a byproduct of both combustion and temp fluctuations

 

[tpenfield]

Welcome to iBoats . . .

You may get a slight pool of water from condensation over the winter months.

Those manifolds look OK. It looks like you have riser extensions on that set-up?

With the riser/elbows off you can take a borescope/inspection camera and get a look at the exhaust valves to verify if there is any rust around the valve seats and ports.

 

[Lou C]

Certainly with the weather conditions in the northeast it’s possible just as you will find the engine covered with moisture on the outside when it’s humid and the temp drops to a level that causes moisture to condense out of the air. This is why engines that are not used in the off season should be fogged, it helps offset any damage from natural condensation.