Winterising raw water cooled engines

[vyv_cox]

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?

It depends (always a great reply ) Thermostats on many raw water cooled engines have a dual function - as they open they allow hot water to leave the block and simultaneously close the bypass. This is true of Bukh and Yanmar but not of Volvo. With the first two removing the thermostat will often cause the engine to overheat as the water goes straight through the bypass uncontrolled. I suspect that the same might happen with Volvo but the function of their cooling system is a bit of a mystery, dependent upon the restrictions in the two possible routes.

 

[PuffTheMagicDragon]

It depends (always a great reply ) Thermostats on many raw water cooled engines have a dual function - as they open they allow hot water to leave the block and simultaneously close the bypass. This is true of Bukh and Yanmar but not of Volvo. With the first two removing the thermostat will often cause the engine to overheat as the water goes straight through the bypass uncontrolled. I suspect that the same might happen with Volvo but the function of their cooling system is a bit of a mystery, dependent upon the restrictions in the two possible routes.

Interesting answer. I asked because I have two raw-water cooled engines. On my sailing boat I have an old Volvo MD2b while on a small open 12-ft boat that is used by my son for fishing there is a single-cylinder Lombardini LDW 40*M (*not sure about the last digit). This little one spends winter in a garage and I occasionally run it using fresh water in a bucket that is kept topped up via a hose. I probably never run it up to temperature because I only run it for a quarter of an hour at most. Hence I wondered whether it would be better to remove the thermostat for this exercise.
Thanks for your explanation.

 

[TC Tuckton]

"...the same might happen with Volvo but the function of their cooling system is a bit of a mystery."

Thread drift...

Is it possible to improve on the "thermosyphon" on a MD11C by routing flow via the two cylinder block drain plugs to the exhaust bend inlet?

 

[vyv_cox]

Is it possible to improve on the "thermosyphon" on a MD11C by routing flow via the two cylinder block drain plugs to the exhaust bend inlet?

I'm not sure how that could help but I am probably not sufficiently familiar with the layout. This diagram shows the configuration of raw-water cooled Volvo Pentas, AFAIK others are the same.

It seems that when the thermostat opens the flow resistance is less through it than through the double bend of the bypass tube. But this assumes that the perforations in the tube through the head are not blocked and that the manifold is clear of salts. It seems a clumsy design compared with more conventional ones such as Bukh and Yanmar, which are very similar.

 

[Jim@sea]

I am now a great believer in using Antifreeze in cylinder blocks over the winter because of the Anti-Rust Inhibitors which it contains.
For over 40 years on boats, engines and tractors which did not run over the winter I would drain the cylinder block.
Until one of my tractors which had been drained in the winter started to overheat. It turned out that when I would fill the radiator/s in the Spring I would just use Tap Water, whereas I should have used Coolant (with Inhibitors) This engine had probably never had Inhibitors so every year when I drained it the air left between the cyinder walls would help the bit of water left there to rust, consequently after perhaps 20 winters of the block rusting internally a pin hole appeared in the cylinder wall and every time the piston went down it would pull a bit of water in and eject it on the compression stroke.
So the engine overheated,
Many of us have elderly engines, I wonder how many people realise that by not putting Antifreeze in there engine is slowly eroding away.
And as to cold winters, was it 1964 when we had a Bedford Van in for service and we thought the engine had siezed, it was so cold that the engine oil in the sump had frozen consequently it would not turn over.
And in 1979 I sold a Moody 30 (Volvo 25hp) to a dealer in September, they did not winterise it, I ended up getting the Moody back in 1980 due to the new boat being faulty, but because the boatyard had not winterised the boat it had a Cracked Block.

 

[richardabeattie]

I'm getting lost in this thread - especially where Jamesuk seems to say you need an electric pump to feed water to the engine when it is already being fed by the impeller!

I flush my raw water Yanmar with freshwater from a large plastic container permanently fitted with a rubber hose. I connect the hose directly to the intake side of the water pump and then run the engine. I then use the same set up to run the antifreeze in. But I do first remove the thermostat (and replace its housing!). My understanding is that if I were to leave the thermostat in the cooling water would bypass the engine for the first 10 or so minutes until it warmed up and the thermostat opened. But with the thermostat removed the cooling water circulates inside the engine right from the start so I don't have to run it for very long.

Shoot me down somebody.

 

[Scotty_Tradewind]

I have a problem which I'd like some advice on.... will start new thread....

'Add Bukh header tank to heat calorifier with an already plumbed in Eberspacher Hydronic.2'

 

[ripvan1]

What effect does running the engine every few days over winter have? Any problems with it ?

 

[Jim@sea]

What effect does running the engine every few days over winter have? Any problems with it ?

I would have thought that doing that would be ideal.

 

[vyv_cox]

What effect does running the engine every few days over winter have? Any problems with it ?

It's basically pointless and potentially harmful. Running engines from cold under low load is bad for them for all sorts of reasons, including bore glazing, high wear rates and acidic corrosion. The latter may be less of a problem now that sulphur in fuel is so much reduced but the combustion process still produces plenty of other organic acids that accumulate in the bores and oil. Best advice is to leave the engine alone until spring time. It will come to no harm whatsoever.

 

[bluerm166]

I think you are right although ,on a yanmar and buhk ,as VYV pointed out, when you remove the thermostat you also leave the bypass entirely open so that say 50% of your mix bypasses the block,perhaps requiring a bigger volume of mix to be handled.To ensure that all the mix flushes the block,and to give a little more time margin,I have considered lodging open an old yanmar thermostat by packing between the wide base of the 'pellet' mechanism and the spring 'base',and this seems to be feasible provided the packing doesn't project beyond the body and stays captive (so e.g. resin) and doesn't exceed the maximum throw of the valve.
Such packing doesn't seem to affect the expansion of the pellet should the flow actually attain working temperature.(I wonder therefore how the wax pellet is fitted.It can't really be loose can it ?)
Having said that of course the yanmar manual simply says drain it down for winter ,but it would seem nice to flush through with fresh water and leave it with the beneficial components in the antifreeze.

I'm getting lost in this thread - especially where Jamesuk seems to say you need an electric pump to feed water to the engine when it is already being fed by the impeller!

I flush my raw water Yanmar with freshwater from a large plastic container permanently fitted with a rubber hose. I connect the hose directly to the intake side of the water pump and then run the engine. I then use the same set up to run the antifreeze in. But I do first remove the thermostat (and replace its housing!). My understanding is that if I were to leave the thermostat in the cooling water would bypass the engine for the first 10 or so minutes until it warmed up and the thermostat opened. But with the thermostat removed the cooling water circulates inside the engine right from the start so I don't have to run it for very long.

Shoot me down somebody.

 

[petersto]

+1

S.

in a nutshell

 

[eddystone]

Most of this is confusing me more than before! Given my lack of any sort of engineering aptitude (replacing filters, bleeding fuel and adjusting belt about my limit) and need to replace raw water pump anyway I think I'll get a professional engine person to do this!

However I did look at the Volvo operating manual I printed off and it seems to recommend draining the system (via drain in front of g/box and on side of block), taking out the thermostat and then filling with anti freeze mix. Just going back to the siphon thing, if I just drop the end of the hose into the strainer box and the other end is immersed in an open container above the level of the water pump will it take it up at the required rate automatically? I guess I need to get hold of a tap to put on the end of the hose to control the feed into the bucket.

 

[roblpm]

Well I tried to do this at the weekend on my 1gm10.

However the tap near my boat at the marina doesn't seem to have any water on it.

So I got a bucket of water next to engine, ran the engine for 5 minutes on idle, and repeated 4 times. Wouldn't heat up so I aborted!!

So 2 things I learnt. A bucket lasts about 4 minutes on idle. And the slightly larger hose (5/8 inch i think) I bought from b&q goes on to the water pump more easily than the cheap half inch I had bought before.

So back this weekend with a working hose!!

 

[richardabeattie]

Most of this is confusing me more than before! Given my lack of any sort of engineering aptitude (replacing filters, bleeding fuel and adjusting belt about my limit) and need to replace raw water pump anyway I think I'll get a professional engine person to do this!

However I did look at the Volvo operating manual I printed off and it seems to recommend draining the system (via drain in front of g/box and on side of block), taking out the thermostat and then filling with anti freeze mix. Just going back to the siphon thing, if I just drop the end of the hose into the strainer box and the other end is immersed in an open container above the level of the water pump will it take it up at the required rate automatically? I guess I need to get hold of a tap to put on the end of the hose to control the feed into the bucket.

Connecting the water supply direct to the intake side of the impeller means you don't have to juggle with a loose hose into the strainer box while the engine is running - and the impeller takes water at its normal rate.

 

[Scotty_Tradewind]

Connecting the water supply direct to the intake side of the impeller means you don't have to juggle with a loose hose into the strainer box while the engine is running - and the impeller takes water at its normal rate.

I occasionally have run up the engine ashore and have dropped the hose pipe from the tap into my strainer (with sea cock shut ) and adjusted the water pressure to suit the water requirement of the engine speed...
i.e. if the water is not overflowing the strainer and if ample appears to be coming out the exhaust then presumed all o.k.

The biggest problem as I see it in running up the engine ashore, is that the engine never reaches a good working temperature and has no load on it + all the other reasons Vyv has given.

If possible don't do it. Sort your engine winterising afloat prior to lift out.

S.

 

[James_Calvert]

Well I tried to do this at the weekend on my 1gm10.

However the tap near my boat at the marina doesn't seem to have any water on it.

So I got a bucket of water next to engine, ran the engine for 5 minutes on idle, and repeated 4 times. Wouldn't heat up so I aborted!!

So 2 things I learnt. A bucket lasts about 4 minutes on idle. And the slightly larger hose (5/8 inch i think) I bought from b&q goes on to the water pump more easily than the cheap half inch I had bought before.

So back this weekend with a working hose!!

I managed it ashore without a hose within reach - once.

I started with two full buckets of water, one set up for the engine (which I kept topping up). I also had 2 four gallon water containers handy, also initially full of water.
There was a working tap about 50 or so yards away.

I used it all up and then some before I was happy the engine was warm enough. Some dashing over to and staggering back from the tap with the 4 gal containers was involved.

The top up bucket was outside the boat, with a hose from it jammed into the engine skin fitting, so at least I didn't have to climb any ladders with the extra water.

Nowadays I make sure there's enough hose to reach the top up bucket ....

 

[pagoda]

I occasionally have run up the engine ashore and have dropped the hose pipe from the tap into my strainer (with sea cock shut ) and adjusted the water pressure to suit the water requirement of the engine speed...
i.e. if the water is not overflowing the strainer and if ample appears to be coming out the exhaust then presumed all o.k.

The biggest problem as I see it in running up the engine ashore, is that the engine never reaches a good working temperature and has no load on it + all the other reasons Vyv has given.

If possible don't do it. Sort your engine winterising afloat prior to lift out.

S.

One way of warming up is to run a hose from your pump input to a large bucket placed strategically under the exhaust to catch the outflow. You can simply let the water cycle round until reaches the temperature you want. It gets warm quite quickly, by comparision with the cool running raw water cooled engines normally do.
That also offers the chance of a fresh water flush out- and and the ability to add antifreeze to the water in the block. (eco friendly by preference...)
Just remember to re-connect your pump inlet to the engine sea water cock BEFORE you launch.

 

[James_Calvert]

Most of this is confusing me more than before!

...need to replace raw water pump anyway ...

...going back to the siphon thing, if I just drop the end of the hose into the strainer box and the other end is immersed in an open container above the level of the water pump will it take it up at the required rate automatically?

I don't blame you. I guess the most economical/elegant way to do the necessary won't always be the same for everyone*.

The water pump change, is this because it is leaking or lacks suction? A good reason to do it/get it done at the same time as the winterisation, which could otherwise be a bit trickier...

because, if it is dodgy suction-wise, it won't be self-priming, and probably won't suck up the water/coolant mix from the strainer box.

BTW, if you do siphon, make sure the siphon hose is full of water, then put one end into the bucket and your thumb over the other end to stop it draining out until it's in the place you want it, which must be below the water level in the bucket.

*My own preferred technique (a bucket outside the boat with a hose from it jammed into the engine inlet skin fitting) involves the least (ie nil) dismantling of engine/cooling system bits, and no clearing up inside the boat either. But I do this when ashore.

 

[Scotty_Tradewind]

One way of warming up is to run a hose from your pump input to a large bucket placed strategically under the exhaust to catch the outflow. You can simply let the water cycle round until reaches the temperature you want. It gets warm quite quickly, by comparision with the cool running raw water cooled engines normally do.
That also offers the chance of a fresh water flush out- and and the ability to add antifreeze to the water in the block. (eco friendly by preference...)
Just remember to re-connect your pump inlet to the engine sea water cock BEFORE you launch.

good idea if you have to do it ashore... but that still means running the engine with no load.
You'd have to have a large bucket or a big funnel to capture the water from my exhaust....
Guess it's also a good way to fit up a warm shower in the yard.... have to tell Mrs S. I'm sure she'll be impressed

S.