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AVickers
11-26-2000, 12:47 PM
I just pulled a marine small block Chevy from my twin-screw Chris Craft down and two adjacent cylinders (#s 5&7) are badly rusted, corroded and pitted -- to the point that a .40 over rebore probably won't clean it up. The head gasket (copper) looked fine (no apparant leaks or tracking) and I can't find a crack in the block or head. This boat has a closed cooling system (block and heads under pressure). The cooling system seemed to work ok (didn't run hot, no loss of coolant and it held pressure) and I didn't get excessive steam from this engine over the other one when running.

The exhaust manifolds are not pressurized. I can't determine if there are any cracks here, but it would seem to me water wouldn't leak from here into the cylinders????

Any thoughts as to what cratered this engine????

Ralph Savarese
11-26-2000, 02:50 PM
It defenitly sounds like a bad riser because they are both on the same side. Check your riser gasgets first and flush and clean them out .Having FW cooling you still have SW risers.Beleve me water can get into the cylinders through the exhaust it is very common!
Ralph

[This message has been edited by Ralph Savarese (edited 11-26-2000).]

AVickers
11-29-2000, 03:27 PM
Thanks for the info.

I really didn't suspect the risers in that w/ a Chevy, the rear cylinders' exhaust ports aren't very close to each other. And if #5 were being impacted by water from the riser, it would seem that #3 would also be hurt 'cause #3 and #5 are so close to each other...

I'll take a look. I really hate the thought of putting things back together only to have more rust problems...

Ralph Savarese
11-29-2000, 07:12 PM
I just went through this problem and mine was only effecting #3 cyl because the manifold below the riser has a V that separares #3 and #5 ports i had to have my manifolds and risers milled to get a good clean surface for sealing of the gasket
Ralph

RickR
11-29-2000, 09:11 PM
I had a similar problem with a Merc 888 (302ci), Hylomar (Permatex product) on both sides of the gasket between the riser and manifold fixed the problem. As far as I know it is still working after 10 years.

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RICKR
mailto:riggerb@aol.comriggerb@aol.com</A>

AVickers
11-30-2000, 04:10 PM
Ok!

I'll give 'er a looksee!

Thanks,

alinaustin