Antifreeze Time

[Bigglesaircraft 293]

A little bit of advice required from the Forums experienced members. To test the quality and effectiveness of my antifreeze do I take a sample from the top of the radiator or from the expansion tank/container?

[Rick 236]

I would take it from the radiator, although the coolant flows back and forth, I have found some bikes where the expansion tank has been a nice  colour and on draining the system the coolant has come out less than perfect, sometimes brown. I would always advise replacing the coolant every two years to be sure of keeping your engine protected both from freezing and corrosion. Remember if you add water it should be distilled/deionised.

[embee 7,288]

If in any doubt, just change the coolant. It only holds a couple of lts so trivial cost, it's an easy system to refill, no tricky airlocks etc, just fill slowly at the rad cap and squeeze the hoses a few times while doing so.

 

Ensure the coolant is silicate free as specified in the manual to avoid pump seal wear issues.

[commuter 262]

I was always told  to take out coolant carefully and gently so as not to oxygenate it, allow it to settle and then, after flushing the system out with a hose, decant 90% of the old coolant  gently back into the system adding more antifreeze to top up in place of the sludgy stuff which had been removed. The reasoning behind this is that old coolant has very little dissolved oxygen in it, ( fish would suffocate) : low levels of dissolved oxygen mean that the system is full of stuff which is not able to cause corrosion. Putting nice , fresh water into a system is just about the worst thing to do with a cooling system ( or a heating system ). If you are wondering why old coolant has no dissolved oxygen in it, that is because all of the available oxygen has been used up for rotting away the insides of your cooling system. Clean old coolant is therefore better than freshly made up new coolant.