Overheated, low coolant, advice.

[francophile1947]

This is all good info... Another query now along the same lines, what's your take on the coolant being a 50/50 mix? TBH i run a 35/40% mix of quality coolant. Is a 50/50 mix really that important in the uk's milder winter i wonder?

I think it's more a question of the corrosion inhibitors, rather than the antifreeze .

[Peg leg Pete]

I have done a 50/50 mix each time I have done a change, notice a small amount of rusty crud develops over the 2 year life of the coolant. I always give the system a good flush out, I wonder if a weaker mix might not give the same rust prevention, Is that why you do more frequent changes Ste

[bigdaddycain]

This is all good info... Another query now along the same lines, what's your take on the coolant being a 50/50 mix? TBH i run a 35/40% mix of quality coolant. Is a 50/50 mix really that important in the uk's milder winter i wonder?

I think it's more a question of the corrosion inhibitors, rather than the antifreeze .

Generally around a 30% mix is sufficient with euro coolant john,there is nothing especially different about the bongo's alluminium head over the iron block than many euro engines knocking about at the moment.

I think the capability of the corrosion inhibitors present in the coolant is relevent to the ratio of anti-freeze used.

So theoretically, anything over a 30% mix of uk coolant should be more than sufficient.

[haydn callow]

Whatever mix you use is good for a certain cold temp..obviously the more antifreeze the lower temp before things start to freeze. 30% antifreeze will give protection down to -"x" degrees and 40% down to -"x" and a bit more. I suppose in the North of Scotland you would need more in than Cornwall but just having a bitter cold wind blowing through a rad in a parked up Bongo would get the temp really low.
More than 50% is not a good idea as antifreeze is not such a good coolant as plain water so in fact too much antifreeze can in fact contribute to higher running temps and possible overheating.

[bigdaddycain]

I have done a 50/50 mix each time I have done a change, notice a small amount of rusty crud develops over the 2 year life of the coolant. I always give the system a good flush out, I wonder if a weaker mix might not give the same rust prevention, Is that why you do more frequent changes Ste

I stick with the suggested bi-annual changes pete, the old coolant looks exactly the same (i.e. as clean as) when it was put in, the coolant has been replaced twice so far, the last time was ahead of schedule for the fitment of flippa hoses.

It will be replaced again over the winter,as there are the "mark2" flippa hoses awaiting fitment.

[francophile1947]

This is all good info... Another query now along the same lines, what's your take on the coolant being a 50/50 mix? TBH i run a 35/40% mix of quality coolant. Is a 50/50 mix really that important in the uk's milder winter i wonder?

I think it's more a question of the corrosion inhibitors, rather than the antifreeze .

Generally around a 30% mix is sufficient with euro coolant john,there is nothing especially different about the bongo's alluminium head over the iron block than many euro engines knocking about at the moment.

I think the capability of the corrosion inhibitors present in the coolant is relevent to the ratio of anti-freeze used.

So theoretically, anything over a 30% mix of uk coolant should be more than sufficient.

Thanks Ste - I'm plucking up the courage to do mine

[Peg leg Pete]

John you will be fine

[francophile1947]

John you will be fine

I sincerely hope so Pete
I'm waiting till after this weekends trip to Polstead though

[Peg leg Pete]

Enjoy your weekend John

[bigdaddycain]

More than 50% is not a good idea as antifreeze is not such a good coolant as plain water so in fact too much antifreeze can in fact contribute to higher running temps and possible overheating.

That is correct, but not for the reason that a lot would assume it to be.

The viscosity of the mixed coolant needs to be as near to the flow value (viscosity, not to be confused with specific gravity) of plain water, Ethylene glycol has very stable characteristics in relation to the viscosity of plain water over a wide temperature range,if the ratio of the neat anti freeze is altered greatly from that that is suggested on the bottle, then the flow rate is compromised, therefore the viscosity can be made to low, which in effect speeds up the mixed coolant,which can reduce the "heatsink" effect of the coolant, effectively this translates to the coolant rushing over the heated surface before it can absorb and successfully carry that heat with it to the radiator,where it is then cooled, and the whole process starts again.

This is my point regarding using a 50/50 mix with uk coolant, yes the bongo manual says use a 50/50 mix with japanese coolant, but that has different properties to euro anti-freeze, i suspect that a 50/50 mix could be less capable of transfering the heat, merely because the viscosity is lower than suggested by the manufacturer of that particular coolant.

[Peg leg Pete]

That is very interesting Ste

[bigdaddycain]

It's a bit of geeky chemistry admittedly pete!

It's an understandable assumption that a higher ratio of anti freeze offers increased protection against freezing, which it does to a point,one has to weigh up the viscosity versus the ability of the coolant not to freeze too.

There isn't much point in the coolant not freezing, if the cylinder head is running hotter than it ideally should.

[Peg leg Pete]

I will bear this in mind at my next coolant change, thanks very much ste

[bigdaddycain]

No probs, remember though pete, this is only my understanding of it, i'm no mechanic, and could well be completely wrong!

[dandywarhol]

A 33% mix has a freezing point of around -18 degC. 50% mix around -37.

About 10 years ago it was recorded -23 at glasgow airport for 2 nights before it warmed to -12! anyone with a car parked in the carpark on holiday in sunny climes would have come back to a frozen/damaged engine with a 33% mix! Some handy bumf HERE

A 50% mix will also raise the boiling point of the coolant over the 33%. A 50% mix raises the boiling point of coolant from 100 to 106 deg C. Combined this with a 1.1 BAR cap the BP of the coolant is raised to around 128 - 130 deg C - plenty of scope for horsing up hills with a caravan