Radiator Overflow Bottle

[Guile]

may be a stupid question but are they necessary

i guess they must be or manufacturers wouldn't fit them, i don't see any change or movement in the water sitting in my heath robinson overflow bottle so i might just junk it,

what do you think?

[Bear]

This is how it works:

The radiator cap is set to a certain max pressure, on hot days or when you're fangin it, the rad cap will release pressure and fluid. Otherwise your radiator would over-boil and the pressure associated will crack radiator joints and the plumbing leaks etc.

When the rad cap releases pressure and vents, the excess fluid goes into the Header Tank/Overflow bottle and not onto the ground like they used to in cars decades ago.

The Rad Cap also has a reverse valve. This is because when excess pressure builds up in the cooling system and the rad cap vents, the reverse happens when the bike cools down completely ie. a negative pressure effect and this can be bad too.

But, if you have a header tank/overflow bottle piped up to the radiator, the fluid that was vented during excessive heat now gets sucked back into the cooling system when the bike cools down.

This is why it seems that the fluid level in the bottle never changes - roughly the same amount of fluid is passed out and then back in.
Some fluid will evaporate over time but this is negligable.

So, you can run a bike without an overflow bottle but you will continuously lose fluid over time via the rad cap relief valve (after every hard ride) and have to keep topping up the radiator and checking it just like the old days of EH Holdens and the like.

The overflow bottle is set and forget.
I forgot to add - the overflow bottle, if it's opaque and see-through, can indicate at a glance the health of your cooling system ie. if the fluid is brown, time for a coolant change and flush.

If the overflow bottle starts to overflow itself or fill up completely after a ride then it indicates that your Radiator Cap relief valve is faulty.

Something else worth noting - the bike will be it's hottest the few minutes after you switch the engine off. This is when the Rad Cap relief valve usually does it's job.

[Guile]

you could have been a bit more specific mate,

serioulsy, thanks a lot that was a big help, food for thought on whether to remove it or not, might try it and see how much i have to top up each time,

[Hillsy]

It's also nice not to have slippery fluid pissing out of your bike while you're riding. Keep the bottle mate.

[Gix11]

It's a bugger to clean off the whole length of your bike as well mate. Keep it for sure. If you don't lke the look of it, make or find a smaller one (wreckers) and hide it somewhere (under the tank / side panels /seat).

[Bear]

My apologies if I went into too much detail but I posted for the benefit of others aswell, who may not be aware. :)

It was a good question to start with.

[masterofinsanity]

bloody good post nice and simple but concise thats how i like it.

[fimpBIKES]

you dont have to have one

it wont be the end of the world

i plumb a small length of hose so that it just dumps on the ground
YES after you top it up it will dump a bit on the first ride of two, but after that it wont really do it at all

you should have one though, ESPECIALLY if you run regular glycol fluid (which i dont cos im not a complete asshole)
its really slippery to hit in the wet so best not to spill that shit on the road

[Hillsy]

quote:Originally posted by fimpBIKES

you should have one though, ESPECIALLY if you run regular glycol fluid (which i dont cos im not a complete asshole)
its really slippery to hit in the wet so best not to spill that shit on the road


That's a good point - don't just do it for yourself, but think about the other poor bastards who might come unstuck because you dumped shit on the road [:0]

[AK47]

thanks 4 the info bear, was wondering the same thing!

[hooligan]

quote:Originally posted by fimpBIKES



you should have one though, ESPECIALLY if you run regular glycol fluid (which i dont cos im not a complete asshole)
its really slippery to hit in the wet so best not to spill that shit on the road


Fimp prefers to dump oil on his tyre:D

[Cruisecontrol]

If you ain't sliding, you ain't riding...

[StuNVA]

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