Winterising a Mercruiser 5.7 V8 on a 20V

[Marjenks]

Hi there,

Yes, believe it or not someone is asking about winterising in mid August! My 20V is located in Sweden where the season is short & the boat is stored at a summer house so I am winterising it this week and heading back to where my job is.

I only bought the boat last year and had it winterised by the official Tige dealer (who is too far away to take the boat to again). Just as he stuck his hand out for the money the words "there's no guarantees" came out! I'd explained to him that the Swedish winter is the same as an Alaskan winter. When I took the boat to Sweden it was minus 20 celcius for 4 days in a row straight after I arrived! He was probably using a coolant flush rated to about minus 7 celcius I reckon.

So yes, come spring water was leaking out of the lowest point in the cooling system where a plastic ball looking cooling system joint had cracked open after freezing. I spent hours working on replacing it and waiting 2 weeks for the part. I noticed it had a blue water outlet for winterising on it that seemed like it had never ever been removed becase it was actually black, covered in engine grime!

During this work I also noticed two more blue plugs on the other side of the motor (to port) which were obviously winterising plugs, they're on joints connected to cooling system hoses about 2/3rds down the side of the motor.

So now I have 3 blue plugs I know I need to remove to sucessfully drain the system, but I've heard there are 5. I've looked around a fair bit and can't see them anywhere. Can someone tell me where they are please?

My plan for winterising is basically to drain every bit of water out that I can because I've learned here in Sweden that no matter what product you put in, there's a chance of freezing. I am then going to place a small heater with a thermostat on the cable in the engine bay to warm it to 5 celcius (zero is the freezing point in celcius) for insurance so to speak. But in case the heater stops working I need to make sure there's no water present anyway. So can someone tell me if there's 5 plugs, 3 plugs or another number and fairly precisely (I think they might also be covered with grime so aren't blue) where they are please?

The coldest I have seen it here in the last 10 years is minus 28 celcius! If you don't know, that is deadly cold!

[Bakes5]

Where you at? I was in ostersund about 20 yrs ago. Only saw 1 boat in storsjon. Anyways, make sure you get it up to operating temperature then run about 5 gallons of antifreeze through it. The when you drain it any residual will be antifreeze. Sorry but I can't help with your ug location.

Hej do

Bakes

[Marjenks]

The boat's in Hudiksvall Sweden which is by lattitude roughly the same as Anchorage Alaska!!

I was working on winterising it today and have some interesting comments for other readers in the future plus if I've really messed it up someone can tell me if they like!

I located 4 blue plugs and 2 hoses that are disconnectable by hand. The 4 blue plugs:

- 1 at the top of the motor (mine was painted black which is why I hadn't seen it before) central in a cooling system junction point to the stern, behind the air filter cover.

- 2 at the port side, 2/3rds of the way down towards the stern as well, again on a juntion point between cooling system hoses. One is above the other.

- 1 to starboard at the very rear and deepest part of the motor, at a cooling system junction that looks a bit like a ball. To get to this one I had to remove the panel at the back of the boat (internally) to starboard. Which panel is that I can hear someone asking? Not sure what it's called, but on the port side it's the panel that covers my two 12V batteries. It needs several screws removing to get the panel out, but without it out, my arm wouldn't be able to reach in there to get it. I only know about this one because it froze and popped per my original post. It was a $175 USD part so I don't want it to freeze again!!!

The hoses:

- Most importantly, 1 to port and 1 to starboard. I found another post online that stated 2 plugs were located just above the oil pan on both sides of the engine. I looked and instead of two plugs I found two hoses removable by hand which a finger activated clip holding them on. These were as stated, just above the oil pan, central to the motor front to back wise. From a few things I've read online I noticed that some engines will have hoses and others will have plugs.

So all in all I located 6 drain points, 1 more than the 5 I was told about! Pretty sure I have them all now.

Another point to note is that Mercruiser's own website states that it's recommened to put antifreeze in, but not required if it's certain that all water has been drained. I'm of the opinion that I'd rather try hard to get all water out and that a lot of antifreezes can't cope with the winter temps here anyway so I don't want to rely on them.

[NICKYPOO]

There's six. One on each side of the block, one on the bottom of each header, one on the water hose from the circulating pump to the thermostat housing and one on the fuel cooler.

[Marjenks]

There's six. One on each side of the block, one on the bottom of each header, one on the water hose from the circulating pump to the thermostat housing and one on the fuel cooler.

Thanks but are you trying to say I've missed two? Your locations are a bit vague to me as I'm not an expert at getting around engines. That's the main reason I posted my long post - to help others like me who also need a better description of the locations.

[Marjenks]

I re-checked and am confident I got them all.

My engine seems to have extra hoses that aren't described elsewhere that I've seen. It's a 2003 direct injection V8 5.7 350.

I traced the two hoses that ome out of the bottom of the exhaust manifolds and they ended at points where I'd already removed blue plugs.

[Ewok]

If you have acces to an air compressor some owners blow air through the cooling system to blow out any last bit of water. If you fill the cooling system with marine/RV antifreeze and then drain it all, and then blow out the components with compressed air or even the exhaust of a shop vac, that should about do it for winter. No matter how cold it gets, water still freezes at 0C and at your temps antifreeze only delays the inevitable, I would use air to get as much water out as possible.

Btw, what is the water temp where you boat? I just moved from TX to Washington State, from 90+ water temp to 74F and I am freezing, but I haven't broken out the wetsuit yet, I'll wait till it gets below 65 for the wetsuit.

[Marjenks]

Good tip thanks. I do have an air compressor so I'll give it a good blast through. I ran the engine for 10 secs a couple of times after draining to see if any water came out, but barely a few drops did, so I'm guessing that anything left like that'll evaporate out anyway and blasting it with the compressor should only help clear it.

Water temps here are about 20 celcius in summer which is amazing considering we can walk across the harbour for 5 months of the year (it's frozen over in deep ice if that wasn't clear!).

I think that's about 75 F and we do use wetsuits because the air temp is often lower than the water temp so it always feels good to fall into the water after getting blasted with cold air first!