Manifold Riser

[KJM]

Hi, I was getting my boat ready for winter today and for the first time ever I drained the riser by removing the brass screw. A small amount of water came out, maybe quarter to a half a cup. I never drained it any other year because I figure that since its essentially an upside down "u" and I drain the exhaust manifold, wouldn't any water in it drain back into the manifold and out thru that drain, while any water on the back end would be gone out with the exhaust? I know there is a flat area between the two lower ends but shouldn't water still not hang up there? Now i'm wondering since I've never drained it before is it possibly cracked inside. If it was, what would be the symptoms?

 

[brian4321]

Use a piece of wire or something to prod and poke around inside the drain hole... sometimes they'll plug up from scum inside the manifold

 

[KJM]

Actually my "problem" if you can call it that, is that any water came out at all. Why would any water hang up in there?

 

[tpenfield]

The gaskets, if they are the 'flow restricting' variety have a very small opening on the front and rear water jackets, making most of the flow from the manifold go through the side water jackets. If those small holes in the gasket have become blocked, then some of the cooling water will stay up in the elbow, even though you drained the manifold.

If you want, you could take the elbows off, inspect them and the manifold of excess scaling/sediment and then put them back together using a new gasket.

 

[brian4321]

Actually my "problem" if you can call it that, is that any water came out at all. Why would any water hang up in there?

Sorry, I misunderstood ur "problem"

 

[KJM]

Thanks for the help everyone.