Manky Monkey Motors

O.K, clever types. A question on header tanks. My Honda Sabre was fitted with a small plastic header bottle, attached to the rad by a rubber hose. Because I've cut the bike down to a single seater, I've lost some of the space where the bottle used to live. I found a small thermos bottle that will do as a replacement, but would rather run without it. So -do I need a header tank? Could I bin it & just fit an overflow pipe? That would allow the hot water to expand but would it boil itself dry if there's no extra water to replace it as it cools?

i didnt have an overflow on my reliant
or my new BMW trike so i guess you would be ok

As it's purpose is to let the water expand without damaging the rad etc it should be ok but you need to make sure that after it has been run  at high temp the water level is sufficent to cover all the bits it should.

I presume that the filler cap is of the pressurised sort that allows the water to pass into the expansion tank when the pressure gets too high or is the expansion the one with the pressurised cap?

My Capri has an expansion tank that never gets used. I fill up the rad and that's that. It does have a pressure cap on the rad and not on the expansion bottle.

tis a grey area! if its fitted its needed. most systems use the bottle to vent the water when its expanded under pressure and heat. as the system cools the previously vented water is drawn back into the system. my personal opinion is dont run without one as you may end up running out of coolant!

Seems to me, if you get rid of the header/expansion tank, then you'll have to carry a bottle with spare coolant to top up what you lose - you might as well find space for the original bit!

Yup, guess you're right. The header tank just had a rubber bung that the hose pushed into, so the cap must be pressurised. I'll have to shuffle the bits under the seat around again then. Thanks people.

go to pound land nice ally slim hair dressing spray water bottles in various colours make great overflow/expansion bottles

Ha ha! That's exactly what I've got! Got the bigger size cos that's all they sold, then saw the slimmer ones in my local barbers shop. They wouldn't swap with me though.

Original plastic tank now re-installed under the seat. It meant finding new homes for some of the 'leccy stuff but better safe than sorry I guess.

Local barbers shop,didn't know they still existed,mind you i haven't needed one for a while,mother nature cuts my hair now :D :D :D

I deliver to a barbers called Tom, Dick & Harry & a hair salon called Marco Polo -no, I don't know why they're called that either.