Flushing 350 mag horizon after use??

[Andiamo]

Trying to figure out how everything works on my new '08 AJ with v-drives. The engines have a port to flush with fresh water after use my question is how do I do it? Any help will be much appreciated.
Thanks
-Pat

 

[missnmountains]

I had twin 2004 350 mag horizons on a monterey. I had to install the hoses to actually flush them. They only came with a relief valve you pumped with a tire pump which drained the blocks and manifolds. There should be a schrader valve on the top of the engine if you have the same setup.

Ken

 

[TARANTULA]

1. Close sea cock
2. connect hose to adapter on engine riser
3. start water flow
4. start engine within 15 sec
5. run engine for 5 to 10 minutes
6. shut engine off
7. shut water off (again 15 sec max)
8. leave sea cock closed until next use.

 

[missnmountains]

1. Close sea cock
2. connect hose to adapter on engine riser
3. start water flow
4. start engine within 15 sec
5. run engine for 5 to 10 minutes
6. shut engine off
7. shut water off (again 15 sec max)
8. leave sea cock closed until next use.

The hose adapter did not come stock with my 350's. We had to add the adapters. I am thinking the OP may not have the adapter.

Ken

 

[Andiamo]

Thanks for feedback! I guess next step is to identify the sea cocks and them remember to open them before leaving dock on next trip. Pretty overwhelmed with all the systems and electronics my last boat was a single I/O cuddy. Love the boat!!

 

[ardeprint]

I don't have Horizons so I cant advice for sure.

With my engines 350 MPI MEI there is a Quick connect connector at the top of the exhaust elbow. This inserts water right before the impeller.

My only observation is that I keep my sea cocks open. This will ensure that the water wil not build up and come back into the engine when I turn off the engine with the water running. By leaving sea cocks open, water will be diverted out through the sea cock and not up the cooling system. Closing the sea cocks is not wrong, but I rather play it safe. Also, if you shut the water down while the engine is running you could burn up your impeller from the lack of water if sea cock is closed.

Once again, the Horizon setup may be different and closing the sea cocks is not negative advice. It's really a mater of preference... I prefer to have them open.

 

[marks737]

I believe the manual says to close the sea water intake prior to flushing. Some people on CSR have said they flush with them open as well. I haven't tried flushing mine yet.

 

[barryg]

Interesting. I never heard of leaving the sea cocks open. I thought that was bad for the engines. In the manual it says to close them. As I usually have to do this by myself, it sure would be easier to leave them open, I was always worried about back flow into the engine. I also was looking at installing the SuperFlush system. Anyone have any experience with that?

 

[MT Pockets]

Interesting thoughts on the sea cock issue. I am really leaning towards closing them, after all if they are open aren't you "flushing" with the same sea water (and now diluted fresh water) that you are trying to "flush" by doing this in the first place???? Inaddition to running the fresh water through the system, prior to going to fresh water and after many trips from fresh to salt, I've used additives like salt-away or similar to flush the engines. Just my opinion.

 

[Ronald Hidde]

Is this supposed to be done after each use even with fresh water closed cooling system? Using this coupling?https://leadersrpmshop.com/mercury-...rcruiser New OEM COUPLING 22-857175 | $42.94

 

[Todd320]

Is this supposed to be done after each use even with fresh water closed cooling system? Using this coupling?https://leadersrpmshop.com/mercury-marine-mercruiser-new-oem-coupling-22-857175/?utm_source=bing&utm_medium=cpc&utm_campaign=**LP - Shop - Marine Parts - Mercury&utm_term=4575205324312275&utm_content=13387_13352 | Mercury Marine/Mercruiser New OEM COUPLING 22-857175 | $42.94

Yes, even if your engines have closed cooling. The elbow and the block-off gasket between the closed cooling and raw water side will have salt sitting in/on it and it is good to flush the salt away. If you are in fresh water, no need to flush, of course.

 

[Michael Alvarez]

Yes, even if your engines have closed cooling. The elbow and the block-off gasket between the closed cooling and raw water side will have salt sitting in/on it and it is good to flush the salt away. If you are in fresh water, no need to flush, of course.

do you have photo of where you put the couple to flush? i have twin 350 mpi's and there are no sea cocks to do a normal flush, other than for the a/c

 

[Harmon]

Why can you just close the seacocks and open the strainer and place hose on hte strainer and fire it up. Thats how I winterized the blocks in Sept. you dont have to worry about 15 seconds if engine doesnt fire ..