plugged exhaust manifold on fresh water cooled system

[crabmanjv]

I have found my circulation problem. I have a plugged exhaust man on port side. 305 omc with 800 omc freshwater cooled. My question is can I clean out manifold or should I replace. I thought that since it was freshwater cooled cleaning out might be a viable option. manual says I can soak in muratic acid. Any suggestions on a cleaning technique. thanks jv

 

[Haut Medoc]

Re: plugged exhaust manifold on fresh water cooled system

The manifold is plugged or the riser?.....
Muriatic acid is a temp fix at best.....
What I'm wondering is how can the closed side of the system get clogged when you are running a 50/50 anti freeze mix?......
I suggest replacement, once they scale that badly, they are prone to failure.....​

 

[drrm123]

Re: plugged exhaust manifold on fresh water cooled system

Are you just opening drain valve to verify if water is flowing? If just opening valve you can take a piece of wire or clothes hanger to clean out while still on boat. Or if removing, take a screwdriver to clean out material after soaking in acid. Check to see if manifold is too hot to touch while running.

 

[crabmanjv]

Re: plugged exhaust manifold on fresh water cooled system

Thanks for the feedback. The manifold was plugged shut in the hose barb where the coolant goes into the manifold at the stern end of manifold right beneath the riser. Risers looked like they could use a cleaning also. I do not know the history of the boat except it hasnt run for about 10 years. I found a reciept from 1995 when the heat exchanger was put on so i'm not sure if the original system was fresh or raw water cooled. I do no it was last run in 1997. If it was originally raw water I suspect risers and manifolds probably need to be replaced.

thanks jv

 

[Don S]

Re: plugged exhaust manifold on fresh water cooled system

If they are plugged, replace them. They are plugged with rust flaking off the inside. If they get a hole in them, you could loose an engine.