Winterising raw water cooled engines

[eddystone]

If I keep my boat on it's mooring it seems exceptionally unlikely the River Itchen water in the engine passages is going to freeze sufficiently to cause damage - it's pretty academic anyway as it's not possible to winterise without access to a hosepipe. On the other hand, if i pull it out it seems more at risk BUT I wondered whether once the engine stops the water level in the passages drops - in other words it has some expansion space if it freezes?

Should I decide to winterise when it's out of the water, I understand the correct way to introduce a fresh water/anti-freeze mix is to insert one end of a hose into the strainer compartment having taken off the top and put the other end in a large bucket with a mixture of water and anti-freeze obviously stopping the engine when it's siphoned up all the water - is this correct?

 

[Tranona]

best to leave the engine empty of water. Afloat, shut off the seacock and wait until no more water comes out of the exhaust and shut down the engine. If you are really pernickity you could drain the block to get the last bit out and the water trap in the exhaust. However in our southern climate the chances of freezing are minimal. Ashore, again best to leave empty, but perhaps use the opportunity to flush the system if it seems to have a lot of deposits. Not much point in putting antifreeze in it - better to leave it dry.

 

[Jamesuk]

best to leave the engine empty of water. Afloat, shut off the seacock and wait until no more water comes out of the exhaust and shut down the engine. If you are really pernickity you could drain the block to get the last bit out and the water trap in the exhaust. However in our southern climate the chances of freezing are minimal. Ashore, again best to leave empty, but perhaps use the opportunity to flush the system if it seems to have a lot of deposits. Not much point in putting antifreeze in it - better to leave it dry.

Shut the seacock on the mooring and get a water pump connected it to the batteries and a hose to the fresh water supply and the run the engine. Drop some antifreeze through the system while it is running then shut of the pump see the last of the water splutter out then you can remove the impeller too. I would keep the cap on the water pump as it is a whole in the boat if the seacock fails.

I have thought in the padt about having a special valve fitted to the intake to take water from the watertank to clear out the engine to prevent corrosion. I think i heard someone doing that on the forum a few years ago (where i got the idea)

 

[VicS]

The trouble with draining the engine is that you probably cannot drain it completely. You leave it wet, salty if not well flushed, and full of air anyway which is a bad combination from the corrosion point of view.

Flushing will remove the salt water and filling with an antifreeze solution will introduce corrosion inhibitors as well as freeze proofing it.

However just sucking up a bucket full of antifreeze is not likely to be effective as most will simply flow through the bypass and out of the exhaust unless its drained again first.

Best procedure is therefore to drain to get rid of most of the salt water, flush with fresh water, if possible running with a hose running into the bucket until the engine is warmed up, Drain again, then introduce the antifreeze, if possible recirculating it to ensure it is well distributed through the engine cooling system.

 

[eddystone]

Unfortunately there is no possibility of a fresh water supply on a mid river mooring so it'll have to wait until it comes out of the water, maybe in January or February.
Of course I had forgotten the bucket needs to be fed as you need to run it long enough for the thermostat to open.

 

[James_Calvert]

Unfortunately there is no possibility of a fresh water supply on a mid river mooring so it'll have to wait until it comes out of the water, maybe in January or February.
Of course I had forgotten the bucket needs to be fed as you need to run it long enough for the thermostat to open.

If you've got some fresh water in your water tanks you can use that. Warm the engine up first in the normal way. Stop it. Then run a hose set up to syphon from your sink to the engine's water pump inlet. Keep the sink half full by running the tap. When you've run enough fresh water through the system, tip your undiluted antifreeze into the sink so that it mixes with the fresh water, turn off the tap and run the engine until the antifreeze mix has all gone.

Probably better than doing nothing?

 

[Tranona]

Shut the seacock on the mooring and get a water pump connected it to the batteries and a hose to the fresh water supply and the run the engine. Drop some antifreeze through the system while it is running then shut of the pump see the last of the water splutter out then you can remove the impeller too. I would keep the cap on the water pump as it is a whole in the boat if the seacock fails.

I have thought in the padt about having a special valve fitted to the intake to take water from the watertank to clear out the engine to prevent corrosion. I think i heard someone doing that on the forum a few years ago (where i got the idea)

Don't think pumping antifreeze into the river/sea is a very good idea.

 

[JumbleDuck]

Don't think pumping antifreeze into the river/sea is a very good idea.

It's not as bad as people think. It's a while since I did the sums, but as I recall the antifreeze in an average marine engine is at harmless levels by the time it has diffused 1m away from the stern, and once it is diluted it biodegrades. Tough luck on any wee beasties immediately by the exhaust, but anyone with that degree of concern for wee beasties shouldn't be using antifouling either. For super weebeastiefriendliness one can always use propylene glycol instead of ethylene glycol.

 

[eddystone]

I'll be friendly to the wee beasties if they stop messing up my boat

 

[[70521]]

Don't think pumping antifreeze into the river/sea is a very good idea.

Are you sure?

Lets assume 5l of antifreeze and one cubic mile of water or 4,168,181,825,441l

 

[VicS]

Lets assume 5l of antifreeze and one cubic mile of water or 4,168,181,825,441l

OK but please ensure your 5l of antifreeze is properly diluted and mixed with your 4 e12 litres of water before you discharge it.

 

[eddystone]

If you've got some fresh water in your water tanks you can use that. Warm the engine up first in the normal way. Stop it. Then run a hose set up to syphon from your sink to the engine's water pump inlet. Keep the sink half full by running the tap. When you've run enough fresh water through the system, tip your undiluted antifreeze into the sink so that it mixes with the fresh water, turn off the tap and run the engine until the antifreeze mix has all gone.

Probably better than doing nothing?

Well now arranged haul out for mid-late December. Forgive my ignorance of the principles of a syphon - a) plan to use a big bucket rather than the sink - how high does it have to be relative to the engine water intake?; b) is it ok to drop the section of hose from the bucket loosely into the open water trap or do I need to positively attach the hose from my bucket directly to the intake hose, i.e. detach the latter from the water filter basket thing? ; c) will the engine just suck up the required amount of water. How will i know when the thermostat is open - no point in adding anti-freeze until it is?

 

[TC Tuckton]

With my Centaur ashore, I run a short length of hose from the exhaust skin fitting to a 5L container hung over the transom at waterline level. The container has a large hole in the top to allow exhaust gases to escape. A smaller (garden) hose takes the "exhaust water" back to the raw water inlet. To start it off I add fresh water to the container and suck on the boat end of the smaller hose till it starts to siphon before rapidly connecting it to the raw water inlet. Start the engine and add antifreeze. I run the engine for 15 minutes most weeks during the winter. Before launching, (after oil and filter change) I disconnect the small hose, run the used water/antifreeze out into the container and flush through with fresh. This all goes to the recycling centre.
It seems to keep my elderly MD11C happy.

 

[James_Calvert]

Well now arranged haul out for mid-late December. Forgive my ignorance of the principles of a syphon - a) plan to use a big bucket rather than the sink - how high does it have to be relative to the engine water intake?; b) is it ok to drop the section of hose from the bucket loosely into the open water trap or do I need to positively attach the hose from my bucket directly to the intake hose, i.e. detach the latter from the water filter basket thing? ; c) will the engine just suck up the required amount of water. How will i know when the thermostat is open - no point in adding anti-freeze until it is?

if you attach the hose directly to the engine water intake ie the pump nozzle, it is not really acting as a syphon. (Although it does help to prime the pump if the hose is full of water before you start the engine - and that's like getting a syphon going). So the height of your bucket in that instance shouldn't be critical, on the saloon floor should be fine - assuming your temporary connection is sound and there's no air being sucked into the system. With the bucket in a higher (syphoning) position, any leaks will be of water out rather than air in and so more evident.

Alternatively if you lead your hose from the bucket into the open water filter housing, then it does need to act as a syphon, so the bottom of the bucket - or more precisely, the lowest water level within it - should be higher than the end of the hose in the filter housing. How much higher I guess depends on how much pressure is needed to deliver the flow needed by the engine - which will indeed suck it up at the required rate, provided there's enough of it. You may need to experiment a bit with engine speeds/ bucket position to get this right, so this isn't as easy to control as the direct connection.

As to ensuring the thermostat is open, I suggest you warm the engine up first anyway, you don't want to be using up all your fresh water to do that. I've found, when doing this ashore, that it's quite obvious from the exhaust water temperature (I stick my hand in it) when the thermostat is open (it's hottish) and closed (much colder). And also, with no load on the engine, that the thermostat cycles between open and closed, every minute or so. In colder weather the exhaust steams a bit more when the thermostat is open, which helps. On a mooring, it would probably help to run the engine in gear, then it would be under load and the thermostat would be open more of the time. Ideally you want to be able to recognise when the thermostat is just opening and that it will stay open for much of the period that the engine will be sucking on the antifreeze mix.

That all said, if your haul out is before Christmas, I suggest you wait until you get her out and do the job ashore. A lot easier providing you can get a hose to the boat. And with salt water currently in the system, it is unlikely to freeze up and cause damage.

 

[maxi]

For £3.75, a water pump that will run on a battery drill will do the job for you. A small container of water/antifreeze mix can easily be pumped into your engine. Just make sure that the water outlet to the exhaust bend is disconnected before pumping or you could back-fill the exhaust system & fill an engine cylinder with water- not advisable.

 

[vyv_cox]

For £3.75, a water pump that will run on a battery drill will do the job for you. A small container of water/antifreeze mix can easily be pumped into your engine. Just make sure that the water outlet to the exhaust bend is disconnected before pumping or you could back-fill the exhaust system & fill an engine cylinder with water- not advisable.

The thread is specifically about raw-water cooled engines. Your method will not fill the engine, the coolant mix will simply exit the engine via the bypass. The engine needs to be hot so that the thermostat is open, when there is a chance that coolant will circulate through the engine. In reality I would guess that the engine needs to run while circulating hot coolant via the exhaust for at least a couple of minutes. If you are determined to get antifreeze solution into it I suggest that draining it followed by pouring the mixture through the highest aperture is a far better method.

 

[bluerm166]

The thermostat needs to be examined anyway so remove it before introducing the antifreeze mix.Otherwise the relatively low volume of coolant would need to be pre-heated or the thermostat will close immediately it hits.If there's a vetus strainer that's the easiest way to gradually introduce the mix but otherwise the pump will suck it up from a container at low level.

 

[aquaplane]

I have had cooling problems so I know that my water pump does about 3l of pumping in a minute.

When winterising my engine I get the engine warm taking the boat to the pontoon to unload it and then back to the mooring before stopping it. I shut the engine cooling seacock and stick the end of the pipe off the strainer in a gallon of 50/50 antifreeze and run it for a minute or so. Antifreeze certainly comes out of the exhaust and I hope has got there via the cylinder blocks as it only takes >5 mins from stopping the warm engine to sucking in the antifreeze.

I do look after the environment but don't worry about a bit of dilute glycol dumped in the sea.

 

[Scotty_Tradewind]

The trouble with draining the engine is that you probably cannot drain it completely. You leave it wet, salty if not well flushed, and full of air anyway which is a bad combination from the corrosion point of view.

Flushing will remove the salt water and filling with an antifreeze solution will introduce corrosion inhibitors as well as freeze proofing it.

However just sucking up a bucket full of antifreeze is not likely to be effective as most will simply flow through the bypass and out of the exhaust unless its drained again first.

Best procedure is therefore to drain to get rid of most of the salt water, flush with fresh water, if possible running with a hose running into the bucket until the engine is warmed up, Drain again, then introduce the antifreeze, if possible recirculating it to ensure it is well distributed through the engine cooling system.

+1

S.

 

[PuffTheMagicDragon]

Probably a silly question:

If I remove the thermostat will all the cooling water go through the bypass or will it circulate through the engine block?