winterizing a mercruiser

[pedromerk]

I have a 5.7 mercruiser (Rinker 320) the manual says to drain the block (4 blue plugs) and then pour coolant in block. I was planning on using my 5 gallon jug hooked up to water ears filled with -100 degree coolant and flush it through a warmed up engine (thermostat open) why would i need to remove blue plugs, thanks, Pedro u

[alswagg]

Because the proper way to winterize is to remove all of the water from the block and manifold.  If you just run some through the system without draining, you might not get any into the engine block, and only have it flush out the exhaust.  Good luck  Al

[Dream 'Inn]

I agree with Al.  You want to make sure the water is all out before you add the coolant.  I took it one step further last winter and then drained the coolant after I ran it thru.  Not sure if I'll do it again this year or not.  But I liked the idea of having nothing in the block at all (plugs all out) for the winter.

[Capt Ron]

I remove the water first by removing the blue lowest plug and the one in the thermostat housing. Once drained, I put the plugs back in and run the engine with the muffs and pink stuff, takes four gallons. After I see the pink coming out of the engine exhaust, I kill the engine and remove the same two plugs to drain out the pink (I recover it at the drain). I also leave all the plugs out for the winter with the exception of the seawater plugs. In my 320 they are right beside the stringers and almost impossible to get at. Never had an issue by doing this.

[Dream 'Inn]

Ron, the only concern I'd have is if the water out of the seawater pump made it out.  I also hear it go back out the outdrive as well.  Although running the pink stuff thru should eliminate it completely.  I agree though, they are a pain to remove.

[Capt Ron]

Dream I wouldn't worry about the small amount of water in the pump. The pink will hit this first just make sure you run enough pink through. My friend with a Thundercraft has no clearance to reach any water plugs and we just pump twice the amount of pink and we never had problems.

[pedromerk]

Here's my concern,after the engine is warm and the thermostat is open you then drain the water which will close the thermostat. At this point with the ears and coolant tank will you get coolant through the thermostat. Would it be better to take off the hoses and pour coolant into the engine that way? Pedro 

[Capt Ron]

Here's my concern,after the engine is warm and the thermostat is open you then drain the water which will close the thermostat. At this point with the ears and coolant tank will you get coolant through the thermostat. Would it be better to take off the hoses and pour coolant into the engine that way? Pedro 

I've did it that way once and works fine. The thermostat won't close that fast. The time between drain and restart is only minutes and those iron horses don't cool that fast.

[pedromerk]

thanks for the info i will do it that way, happy winter

[pedromerk]

It was recomended by Mercruiser to leave the coolant inside the block to eliminate rusting and to lube the seals in pumps. i plan on using -100 and leave it in after draining all the water out. Pedro

[Capt Ron]

I've left it in as well with good results do you know what type of antifreeze they recommend

[Dream 'Inn]

It was recomended by Mercruiser to leave the coolant inside the block to eliminate rusting and to lube the seals in pumps. i plan on using -100 and leave it in after draining all the water out.

I've heard that as well and that is what I've done since 1999, all but last year.  I think this year I will leave it in, but pull the bottom plug just for a second to make sure I see pink stuff.  I had one year where I pulled the plug in the spring (for curiousity) and saw some water in it initially.  Got lucky.