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Hi everyone,
new to the forum and have a question that hopefully someone can help me out. I just bought a boat with a San Juan FWC system. It's a full system installed onto H190 4.3L Carb Merc engine. I was told that after each use I can just put ear muffs on and flush the system and that's all i need to do. I was just wondering if that is good enough or should i be draining the raw water portion as well. If so can anyone tell me where are some of the plugs i need to unplug to let water out? I know there's one on the top where the heat exchanger is. i think it's the "zinc anode" plug. Please correct me if i'm wrong.

Thanks in advance!

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2010 FW H190 SS

Yep, just put the muffs on to flush with full water pressure - works great and dead easy to do. Will flush out all areas the raw water gets to.

Mine is all raw water cooled, so have to let it come up to temp and thermostat open (around 170) - takes about 5 mins. I then also flush with Salt Away as I am always in salt watrer.

If yours has a closed cooling system, should only take a couple of minutes to flush beacause all you are doing are manifolds and the heat exchanger.

Hope this helps...

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Alec

2006 Horizon 190
VP 4.3GL/SX, Sunsport

thanks for the reply. can't wait to try it out.

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2010 FW H190 SS

If the boat is used in salt water, it's a good idea to flush the rew water side out with fresh water after use; it minimises the exposure time to salt water. However, be aware that the fresh water will freeze at at a higher temperature than the antireeze/ coolant that circulates around the engine/ heat exchanger. So, that would need winteriing or draining fully each winter. There is usually a zinc anode in the heat exchanger and it is probably screwed into the brass plug you mentioned. I find the anode in my heat exchanger lasts a whole season in salt water,

Graham.

I was told if i unplugged the "zinc anode" plug that the raw water will flush out and that's all i need to do for winterizing. (after flushing it through with a ear muffs of course). With the plug so high where does all the water go that's below the plug? is there another drain plug that i'm not aware of?

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2010 FW H190 SS

The heat exchanger on mine is mounted high up and is horizontal; the anode plug is on the underside, when I remove it it drains the raw water side of the heat exchanger. There is still water lower down than the exchanger which drains out when I remove the impellor from the raw water pump, plus as mine is not a full system , I remove the plugs to drain the exhaust manifolds/ risers as well. You indicated your's is a "full" system, which I assume means the exhaust manifolds and risers are also cooled by the antifreeze mix. If so, they do not need to be drained.

Graham

where is the impellor for the raw water pump? is it easily noticeable?

thanks

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2010 FW H190 SS

On a 4.3 Merc, you probably have an Alpha drive; in which case the impellor is in the lower part of the outdrive, not engine mounted like on a VP or a Bravo drive.

I really have no experience of draining Mercruiser engines/ drives, so I am a bit wary of advising you as to the best way of draining your set up at the lowest point.

Graham