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Loosing Water from Radiator Overflow
Posted: Sat Apr 02, 2011 8:18 pm
by Purbeckfossil
Hi all. New Radiator cap fitted. Loosing about a pint of water on 12 mile run from overflow. I have started engine from cold and run it up to temperature with rad cap off, then increased throttle to see if any pressure blowing out of radiator but that is A-OK. Rad is filled to about 1 inch below neck. Don't know if failed stat would come into the equation or how to test if applicable. Any suggestions appreciated before head comes orff!
Thanks
Re: Loosing Water from Radiator Overflow
Posted: Sat Apr 02, 2011 8:43 pm
by katy
If you don't top up the rad, does the level keep dropping and dropping? Or does it stabilize at a certain level? If so, you've been putting too much water in it.
Re: Loosing Water from Radiator Overflow
Posted: Sat Apr 02, 2011 9:29 pm
by bmcecosse
Stick a plastic bottle under the overflow pipe - then when it cools down it will suck the water back in.... How's the negine temperature when running? Does the heater work VERY well ??Or - more worryingly - not at all.......?
Re: Loosing Water from Radiator Overflow
Posted: Sat Apr 02, 2011 10:36 pm
by chrisryder
BMC, how does it suck water back in? what about the rad cap?
Re: Loosing Water from Radiator Overflow
Posted: Sat Apr 02, 2011 10:38 pm
by bmcecosse
It has a vacuum breaker valve........
Re: Loosing Water from Radiator Overflow
Posted: Mon Apr 11, 2011 9:51 pm
by Purbeckfossil
Thanks for your various inputs.
I have now fitted a bottle on the overflow and there is about 1/2 pint overflow, most of which is sucked back in on cooling. On checking the radiator cold, the volume is nicely around the top of the vanes. So, my question is:- should an overflow bottle be permanently fitted or should it have been there all along as the water loss appeared much larger in volume when allowed to vent free. I currently have a 1L tesco milk bottle in place (not exactly concours) - Cheers
Re: Loosing Water from Radiator Overflow
Posted: Mon Apr 11, 2011 10:54 pm
by bmcecosse
It's not doing any harm there - just use a more aesthetic bottle !
Re: Loosing Water from Radiator Overflow
Posted: Tue Apr 12, 2011 1:46 am
by moggydriver62
Johnnie Walker bottle would look nice.

Re: Loosing Water from Radiator Overflow
Posted: Tue Apr 12, 2011 8:11 am
by Neil MG
Purbeckfossil wrote:Thanks for your various inputs.
I have now fitted a bottle on the overflow and there is about 1/2 pint overflow, most of which is sucked back in on cooling. On checking the radiator cold, the volume is nicely around the top of the vanes. So, my question is:- should an overflow bottle be permanently fitted or should it have been there all along as the water loss appeared much larger in volume when allowed to vent free. I currently have a 1L tesco milk bottle in place (not exactly concours) - Cheers
It always looks like more when it's all over the floor!
Without the bottle it will stabilize and you don't need to keep topping up. leave the bottle until you are happy you don't have a leak. Then you can take it off and forget about it!
Re: Loosing Water from Radiator Overflow
Posted: Tue Apr 12, 2011 9:57 am
by bmcecosse
The bottle is an excellent fitment - no need to remove it - just make it tidy!