Bongo Fury

On checking the strength of the antifreeze mixture I judge it to need another litre or so to bring it up to 50%.I bled the system last summer and it was a horrendous job taking 3 attempts to get it right.The antifreeze doesn't need completely changing and I am not keen to risk getting air into the system .What is the best way to top up the antifreeze?Someone has suggested that I could syphon off coolant from the radiator maybe in half litre stages after running the engine to ensure that I get a proper mixture.Anybody know an easy way or if this suggestion is practical?

banjoboy1 wrote:On checking the strength of the antifreeze mixture I judge it to need another litre or so to bring it up to 50%.I bled the system last summer and it was a horrendous job taking 3 attempts to get it right.The antifreeze doesn't need completely changing and I am not keen to risk getting air into the system .What is the best way to top up the antifreeze?Someone has suggested that I could syphon off coolant from the radiator maybe in half litre stages after running the engine to ensure that I get a proper mixture.Anybody know an easy way or if this suggestion is practical?

I have just asked ths too as I need to add a bit

bottom drivers side of the main radiator is a drain tap.
make sure the coolant is cold, remove the expansion tank cap, (NOT THE RAD) then first fill the expansion tank to the very top with neat antifreeze of your choice, then open the tap on the rad bottom to remove the diluted coolant, (DO NOT LET THE EXPANSION TANK GET BELOW THE LOW MARK). then repeat until your happy with the mix strength, set it to the correct level in the expansion tank.
any air that enters the rad bottom (if any) will rise to the top of the rad, then be dealt with in the expansion tank as it is circulates to there next.

do not top up if you do not know the brand of antifreeze in already, if in doubt totally flush the system and refill with new.mixing jap coolant or unknown can react with the british stuff.

Thanks, I will have to check I have a drain on the rad?

Thanks for the very clear "how to do it" instructions.Dunnit this morning easy peasy.The drain plug is easy to find at the bottom left corner of rad ( viewed from the front ).The only slight concern I have is because my header tank is not very easy to see through I may have let the level drop too much when draining.I added a litre however and intend to take the Bongo for a spin later to get the new stuff circulating in the mixture before I recheck the strength with my tester.Fingers crossed I suppose that I haven't got any air in.Thanks for your info very helpful as usual.

get a lolly stick or a well known coffee place stirring stick and stick straight down to the bottom of the expansion tank. i think its about 25mm you need to see on the stick. or measure the wet mark against the outside of the tank fill levels.