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Water backing up into Chevy 350 small block propelling my houseboat.

Axe

New member
I have a small block Chevy driving a 3-stage impeller jet drive on my houseboat. There is only about 9 inches of difference between the exhaust manifold and the water level, leading to water backing up into the engine. There is not enough headroom in the engine compartment to put in taller manifolds.

I would welcome suggestions for the best way to stop reverse seawater. (Check valves? If so, can they be installed in a vertical, or near vertical position? It's a 3.5 inch line.
 

bondo

Silver Medal Contributor
Ayuh,...... Who put that together,..??

You must have 13" of fall in the exhaust,.....

No such thing as check-valves for exhaust systems,......
 

Axe

New member
Well, actually there are, I am told. Centek makes them for use on marine exhausts. They're pricey ($$$), but they use them on fireboats and such, where the engine is low in the boat. What I need to know is if they can be installed on an angle. Thank you for taking the time to respond to my question.
 

makomark

Silver Medal Contributor
best thing to do is call CENTEK...explain the installation you have (details) and they will provide you a list of all the solutions they can provide...a lot of their products are the result of 'out-of-the-box' thinking...
 

Axe

New member
In the interim, we are going to start with getting all of the weight we can off of the back of the houseboat.
 

jimn

Advanced Contributor
Ayuh,...... Who put that together,..??

You must have 13" of fall in the exhaust,.....

No such thing as check-valves for exhaust systems,......
You know the Mercruiser shutter that's located in the exhaust, below the bellows after the elbow? Well, the one that's supposed to be there? It's supposed to block water that rushes in, but if an engine has been overheated badly enough, like mine was, it will probably be half missing, the leftover will be charred and the O-ring will be a crunchy piece of Carbon.
 

jimn

Advanced Contributor
I have a small block Chevy driving a 3-stage impeller jet drive on my houseboat. There is only about 9 inches of difference between the exhaust manifold and the water level, leading to water backing up into the engine. There is not enough headroom in the engine compartment to put in taller manifolds.

I would welcome suggestions for the best way to stop reverse seawater. (Check valves? If so, can they be installed in a vertical, or near vertical position? It's a 3.5 inch line.
Mercruiser had bad problems with 4.3L run-on in the late-'90s- look for the service bulletin and see if you're interested in any of those BandAids. If yours runs on, they could help. What name is on the engine?
 

bondo

Silver Medal Contributor
You know the Mercruiser shutter that's located in the exhaust, below the bellows after the elbow? Well, the one that's supposed to be there? It's supposed to block water that rushes in, but if an engine has been overheated badly enough, like mine was, it will probably be half missing, the leftover will be charred and the O-ring will be a crunchy piece of Carbon.
Ayuh,..... Shutters are to stop back-wash, but will only work if you have at least 13" of fall, from where the exhaust goes from upwards to downwards,....
If the motor is mounted to low, they won't help at all,....
 

jimn

Advanced Contributor
Ayuh,..... Shutters are to stop back-wash, but will only work if you have at least 13" of fall, from where the exhaust goes from upwards to downwards,....
If the motor is mounted to low, they won't help at all,....
Just another reason the people who design boats need to be forced to service them for at least a year before they can put their designs into production.
 
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