Mercruiser 5.0 EFI / Alpha Winterization - Did I screw up?

[LambChop]

I attempted my first boat winterize procedure last night on my Mercruiser 305 EFI w/ Alpha stern drive. For the most part everything went close to plan:

• Full tank of gas with fuel stableizer
• Ran motor on muffs for around 15 minutes to flush the cooling system with fresh water - discovered my exhaust bellows is shot
• Fogged motor (it wouldn't die while spraying a ton of fogging oil into it...)
• Pulled drains and ran a pick into them to make sure all water drains out
• Dropped lower unit and replaced impeller, reinstalled and filled with fresh oil
• Changed engine oil and filter
• Changed fuel filter
• Poured RV/Marine antifreeze down cooling hoses.
• Planning to do cap/rotor, plugs, and plug wires in the spring

Here's my concern...

For some stupid reason, I neglected some advice I was given about how much coolant to pour into the hoses.

I dumped a whole bunch down the hose that goes from the thermostat housing to water pump. I dumped plenty down the hose that comes from the seawater intake and routes through the power steering and fuel coolers. I'm not too worried about those.

What am a bit concerned about it is the two hoses that route from the thermostat housing to the exhaust manifolds. I dumped plenty of coolant down those when I was told to pour about a half pint into them. I realized this and pulled the drains again. Antifreeze drained from the port side. For some reason, more water drained from starboard side, and then some coolant came out.

Did I just pour a bunch of antifreeze into cylinders of my motor?

 

[Don S]

Re: Mercruiser 5.0 EFI / Alpha Winterization - Did I screw up?

Did I just pour a bunch of antifreeze into cylinders of my motor?

Probably not, it takes a lot to fill the manifolds (More than a pint for sure), if you got more in them than the could hold, it would just go out the back of the boat like the exhaust.

 

[LambChop]

Re: Mercruiser 5.0 EFI / Alpha Winterization - Did I screw up?

I'm not exactly sure what goes on inside the manifolds - is there some sort of flapper valve that prevents water from entering the motor through the exhaust ports?

 

[Don S]

Re: Mercruiser 5.0 EFI / Alpha Winterization - Did I screw up?

There is, but they are down it the top of the Y pipe.
This picture might help you understand how the water goes through the exhaust.

 

[LambChop]

Re: Mercruiser 5.0 EFI / Alpha Winterization - Did I screw up?

That helps a ton - looks like it'd be pretty tough to get coolant into the cylinders.

 

[Don S]

Re: Mercruiser 5.0 EFI / Alpha Winterization - Did I screw up?

That helps a ton - looks like it'd be pretty tough to get coolant into the cylinders.

Is, unless the manifolds and risers are bad, or the gasket between them leaks. If you're really concerned, pull the plugs out and crank the engine over and see if any water comes out of the cylinders.

 

[tpenfield]

Re: Mercruiser 5.0 EFI / Alpha Winterization - Did I screw up?

Since you drained the water from the manifolds and poured anti-freeze into the inlet and recirculating hoses, you should be good.

If you had not drained the manifolds, then you would have screwed up. . . and we would be reading your new thread next May.