BMC 1.8 Changing antifreeze

[comfortably numb]

I need to put some antifreeze in my engine as there's hardly any in it. I want to completely drain and the fill with the correct mix. Being a complete dummy with things like this but wishing to learn, I'd be grateful for any help/advice.

 

What is the capacity of the system in litres?

What mix should I have - I think it's 65% water & 35% antifreeze?

I plan to drain it by removing the bottom hose - is this acceptable?

Do I need to bleed the skin tank?

Is there a particular antifreeze which is best?

 

Any help would be gratefully received.

[Chalky]

If you're going to change all of the anti freeze consider changing to the pink (as used by most modern cars) one rather than the blue/green. It has a lot longer life and gives better corrosion resistance however you can't mix the two.

 

The capacity will depend on the system, each one is different. Mix the antifreeze and water before you pour it into the engine.

 

Last time I changed it I removed the bottom hose, drained it into the bilge and used a small pump to collect it in a suitable container for disposal. I of course turned off the bilge pump to avoid pumping it into the canal (and then remembered to turn it back on again afterwards). Unless you can vacuum fill it (which is what happens on car production lines) you'll need to bleed the whole system - engine, calorifier, skin tank etc.

 

The concentration of antifreeze depends on how cold you expect it to get. I usually go for 50% however others may choose other mix ratios.

Edited November 26, 2013 by Chalky

[Grace and Favour]

I need to put some antifreeze in my engine as there's hardly any in it. I want to completely drain and the fill with the correct mix. Being a complete dummy with things like this but wishing to learn, I'd be grateful for any help/advice.

 

What is the capacity of the system in litres?

What mix should I have - I think it's 65% water & 35% antifreeze?

I plan to drain it by removing the bottom hose - is this acceptable?

Do I need to bleed the skin tank?

Is there a particular antifreeze which is best?

 

Any help would be gratefully received.

Ah! - I changed my antifreeze this year too, (and - like you I wasn't certain what the volume of whole system was), (though I have a different engine from you - and a different skin tank etc) - So I bought plenty of antifreeze, (15 Ltrs) - and armed myself with oodles of empty 5ltr containers - (so I could both collect and measure the volume)

I used a Pela pump to extract most of the coolant from the lowest point (skin tank), and then removed the lower skin tank hose to remove the balance.

I'm glad I tackled it this way - for I removed 45Ltrs of coolant, (which, thankfully, meant I had a solution of 15L/30L water to replace it with. (fortuitously)

The antifreeze~water ratios are recommended by BetaMarine to be between 30%~50%.

 

(FYI - my engine was 10.5Ltr, - the balance was Skin/calorifier)

[Bobbybass]

I found it helpful, to raise the 'level' of the antifreeze while getting rid of airlocks...and put a little pressure on the system.

 

I used an old 2 litre anitfreeze bottle..cut the bottom off..and wrapped insulating tape around the neck to make it a tight seal on the filler neck. A sort of 'large mouth' funnel.

[springy]

As Grace & Favour suggests Its the size of the skin tank thats the crucial bit- I did mine a few months back and I seem

to remember the final total being somwhere just over 50L (water/antifreeze mix) but this may vary considerably depending

on the design of your skin tank(s) and interconnecting pipes, buy plenty, mixing it to the required proportion - (I would tend

to go higher than the 30% minimum but it gets costly) and just keep going till its full, you may need to bleed any high points

- I have one bleed in the top of the skin tank, and another on the high point of the calorifier circuit

 

springy

Edited November 26, 2013 by springy

[Tony Brooks]

As far as I am concerned you do NOT have to pre-mix the antifreeze and water if its going into the engine. You do for central heating systems, especially gravity ones.

 

My experience is that if you refile pint of water - pint of antifreeze (50%) or two pints of water - pint of antifreeze (33%) a suitable measure like a plastic pint glass or anything really and the get the engine up to temperature and run if for an hour or more it will mix perfectly happily. However if you intend to just refill it and leave it then you should pre-mix it a this time of year otherwise you might end up with layers of antifreeze and layers of water. This way lets you leave antifreeze you do not need in the can.

[comfortably numb]

Thanks for your help. The only thing I'm confused about is the calorifier. I didn't know this was on the same system as the engine as I thought that the calorifier heated up my domestic water? If this is so then surely it shouldn't contain anti-freeze?????

 

Am I missing something here or just being more thick than usual?

[Tony Brooks]

As long as you stick with the same "colour" antifreeze you can ignore the calorifier and what of the old stuff is left in any pipes. It is a coiled pipe in the calorifier that has antifreeze in, not the whole thing. Whenever you drain a system you may have problems bleeding the calorifier but that has nothing to do with antifreeze.

 

If you intend to change the antifreeze type just refill with water, run the engine till hot, drain down, and repeat. Then finally refill with the new antifreeze.

[mattlad]

Thanks for your help. The only thing I'm confused about is the calorifier. I didn't know this was on the same system as the engine as I thought that the calorifier heated up my domestic water? If this is so then surely it shouldn't contain anti-freeze?????

 

Am I missing something here or just being more thick than usual?

It is in effect a heat exchange, the water in the calorifier is kept separate from the water in the engine. Only the thermal energy is transferred. In the winter you will need to drain down the calorifier along with the rest of the water system if you are leaving the boat unused but not the engine, because you have anti-freeze fitted.

[comfortably numb]

Thanks again. I shall be tackling it over the weekend with hopefully no unforeseen problems!

[Taslim]

Thanks again. I shall be tackling it over the weekend with hopefully no unforeseen problems!

Green one for optimism.