Getting valve job, new riser gaskets

[superiormgmt]

First, I want to thank everyone for their help so far. Overview: 1984 21.5 Chaparral, Mercrusier 350. Ran good before it winterized and sat outside for 5 years. I was given this boat from my landlord in exchange for saving him storage fee's. What I found: Water in oil, did compression check resulting in one cylinder reading 0 and 7 reading between 120-140 psi. Pulled head and found a broke exhaust valve on the one without compression. Gasket looked wore but not blown. Next, took apart riser manifolds and gaskets looked bad. Their was fresh rust build up in the exhaust part of both manifolds.<br />I was hoping to get help on the diagnosis.<br />My diagnosis, my risers were leaking water into the manifolds, this allowing water to seep into oil at stand still. The valve was also allowing more water to be sucked into engine. Block and pistons look good. If anyone has any final suggestion's before I get a valve job, new gaskets and reassemble this motor I would be even more grateful. Tony

 

[Bondo]

Re: Getting valve job, new riser gaskets

You are Replacing the Manifolds,+ Risers..... Right ??<br />It sure Sounds like you'll be Boating Very Soon.................

 

[superiormgmt]

Re: Getting valve job, new riser gaskets

After looking at the risers and manifolds it seemes that the gaskets were letting water past. Do you recomend completly replacing them. There is fresh rust but no major corosion. And thank you for your reply

 

[Bondo]

Re: Getting valve job, new riser gaskets

I would......<br /><br /><br />At least check the surfaces for flatness.....<br />Gaskets Usually don't Just fail......<br />And, manifolds,+ risers don't last Forever....<br />Have they Ever seen Saltwater ????<br /><br />This is where your Problems Started.......

 

[yoced]

Re: Getting valve job, new riser gaskets

Don't ignore Bondo's advice here.<br />Your leaking gaskets will have let water start to eat away at the surfaces between the manifold and riser. It is very hard to get them to seal again once they have been leaking: you want to look for a minimum of 1/4" of good flat surface (matching on both sides). <br />You have to hate rebuilding your engine only to have the same thing happen all over again.

 

[Trent]

Re: Getting valve job, new riser gaskets

I would replace them also.......