View Full Version : Winterizing 5.7 mercruiser I/O in water.

10-12-2015, 06:17 AM
I just purchased a 38 HM coastal barracuda. The brazo drives pull water into sea pump. My question is whether or not to cut the hose from drive to sea pump instant ball valve and tee so I could winterize while the boat stays in water for winter. Thanks

10-14-2015, 11:16 PM
In a nutshell.....YES! I have had two houseboats plumbed that way, and plan on making the third one that way this weekend.

10-15-2015, 06:49 PM
Thanks. How did you plumb yours? Appreciate any help.

10-16-2015, 06:35 PM
I installed these on my boat:

They seem to be built pretty well but I have to admit I've never used them; I just drain the water out of the system and store it dry.

10-20-2015, 03:27 PM
What is Winterizing??


10-22-2015, 01:35 AM
Thanks. When you say drain it dry,do you mean removing the three blue drain plugs? If so do you know if that also drains the water in the sea pump? If that is so then I wouldn't have to worry about anything freezing
up in the raw water system. I like the look of the defender product but if I can just drain it dry safely I could save some money.

10-22-2015, 09:28 AM
if you rely on just draining the engines and not antifreezing them to save money,it WILL bite you in the a... and cost you a lot more. been there done that! huge huge huge mistake!!!

10-22-2015, 06:12 PM
Understood. I think I'm going to check my system on my other house boat. I already winterized it. If I drain blue plugs and pull intake hose to sea pump then pull out flow hose from sea pump and nothing comes out then I know there is no fluid left in system. Just to reiterate this is a fresh water cooled Merc ,so raw water travels through risers exhaust manifolds heat exchanger and power steering cooler. Why would they have those drain plugs if they don't completely drain the whole system?

10-22-2015, 06:13 PM
I drain either side of the block, I drain the elbows and risers, and I remove the raw water pump and manually turn the pulley with the pump inverted to get all the water out. I leave the pump off until splash (I pull my boat every year), that way I can start the engines without toasting the impeller.

42, why do you say that? I have studied my water system and know where all the water sits. I trust my method more than using antifreeze; it's not about being cheap. I do feel antifreeze has anti corrosion merits, but in a RWC engine it's not worth it in my humble opinion.

One thing I will say, if you have a RWC engine and are using the antifreeze method, make sure you pull the tstat or you risk having all the antifreeze just blow right out the exhaust and not displacing the water in the block.

I winterize my water heater the same way. Drain it and store dry.

<edit to add> OP posted at the same time as me, stating he has a FWC engine which is a different animal.

10-23-2015, 04:09 AM
the reason I say I always use antifreeze is one winter all the water didn't come out of the drains and it cost me a oil cooler and exhaust manifold,its not worth it for 75$ worth of anti-freeze and peace of mind. to each his own.

10-23-2015, 04:31 AM
I am cheap,but it not the cost of antifreeze that I mind spending on. The drains are a bit more than I expected to spend. But I will if I have to. The real problem is this is my first twin engine set up and it looks as though the starboard hose to the sea pump is not going to be easily accessed.