exhaust manifold

[jharding]

Hello all, my perkins 4-236 engine ended up with raw water in one cylinder for a month before discovered. The total rebuild is complete, mechanic showed me that the exhaust manifold was the culprit leaking raw water into exhaust which went into open exhaust valve and ruined one cylinder. Glad we found something, now I need to replace the exhaust manifold, holy cow, perkins wants $4000 us dollars, more than the total rebuild is costing. I'm looking for alternatives now, if anybody knows of one please let me know. Interesting the non water cooled manifold is only $300. I am wondering if I need a water cooled manifold or if I can just wrap standard manifold with exhaust insulation and eliminate the problem that got me here. I have been on boats that had a dry insulated exhaust, seems like a good Idea. what do you all think.

[markxengineerin]

I'd look at a repair of the component you have.

[MikeHoncho]

I'd rather have the head carried away by the raw water than be held in the system and in the space.

[Bill O]

If you do the dry stack exhaust, you will need to add a keel cooler for the engine. Could be done, but may not be too practical for a sailboat application.

Instead, look for a replacement SS exhaust manifold (~$1k) and keep the regular water cooled exhaust. There is Marine Exhaust Systems in Alabama (mesamarine.com) that makes them and TAD also sells them.

[more]

Originally Posted by jharding

mechanic showed me that the exhaust manifold was the culprit leaking raw water into exhaust which went into open exhaust valve and ruined one cylinder.

This is possible welding. also possible test. make rubber close water side. inside put air 1-2 bar and submerse in water,bubble coming momentary . if buuble coming close to end mark and weld with proper cast iron electrode for high temperature.

[more]

also Bowman PE390-3674

[Diesel Bill]

I went with Marine Exhaust Manifolds of Alabama around 5 years ago. They make them
from 316 stainless. Pretty enough to display on the coffee table. Less than 1/2 price of
OEM replacements. Very happy with the quality. You might want to consider stainless
elbow too.