mainfolds and risers

[Doug Durako]

I hate to sound like such a newbie, but I am here to learn and have discovered how little I know.<br /><br />Does someone have a simple source I can go to, or a diagram, that explains exhaust manifolds and risers?<br /><br />Where and how does raw water enter the system to cool the exhaust on the typical 350 Chevy marine setup?

 

[kdmiller8251]

Re: mainfolds and risers

here ya go! Dont feel like a newbie or think any question is dumb.. We all gotta start somewheres.The only thing different between yours probably and this diagram is that the raw water pump will be located in your drive.. Water is drawn into the system through the drive by a rubber impeller. <br /><br />Tallman<br /><br />

 

[masterp]

Re: mainfolds and risers

Thanks for the diagram Tallman! I've been trying to figure this out through the different conversations on the board. But the old saying is true "a picture is worth a thousand words". If I'm getting this right, the exhaust manifold has a water jacket in it just like a boiler (I'm a plumber). The water is fed into the water jacket of the exhaust manifold to cool it. The water is than pumped out of the water jacket and over the riser meeting the exhaust gases on the other side of the riser. So overheating may be caused by a corroded water jacket in the exhaust manifold. This slows down the velocity of the collant and creats an overheating condition. Also, if there is a crack in the water jacket of the exhaust manifold it can lead to damaged exhaust valves in the engine because water is penetrating the gaseous part of the exhaust manifold. Do I have this right? Please correct me if I'm wrong. I've been trying to figure this out since I've been on this board. I'm here to learn? If you guys have any plumbing or heating questions drop me a line. Been in that line for around 30 years.

 

[zzzzz]

Re: mainfolds and risers

ddboater- if you end up replacing your manifolds and risers-it's worth considering mercurys' latest-ceramic coated inside and out.you'll get extra life out of a set for not a lot more money !

 

[Boatist]

Re: mainfolds and risers

Masterp<br />You got it right. I will add two things. If have a closed fresh water system then the engine runs Coolent just like your car. A half system protects only the engine but a full system protects the engine and manifolds but not the risers.

 

[masterp]

Re: mainfolds and risers

Great info for us learing. Thanks Boatist!

 

[Doug Durako]

Re: mainfolds and risers

I've been traveling a few days and away from the old computer. Thanks Tallman for the diagram and everyone for the info. This really helps in the understanding of other dicussions.<br /><br />Tallman---I live near Bloomington, IL also. I sent a note the other day to your email address. Drop me a line anytime.