Page 1 of 1

Coolant refill help

Posted: Tue Mar 19, 2013 8:39 pm
by ryan78
Just finished flushing my cooling system out and im about to refill it, before i do ive got a few questions for the technically minded people out there!

Whats the best way to refill the system?

Where do i pour the coolant in, directly into the radiator or into the expansion bottle?

In the workshop manuals it says the tank will take 2.3l of coolant, do i put exactly that amount in?

The manuals also state 50/50 coolant water mix, is this a good ratio to have or has anyone found a better ratio to use?

Thanks for your help

Re: Coolant refill help

Posted: Tue Mar 19, 2013 9:05 pm
by RedexRobB
Coolant needs to go in the radiator to fill the cooling system not the expansion bottle. Although you do need to fill the expansion bottle to the middle of the two lines indicating the upper and lower levels.

Best way to fill is to fill through the radiator cap and pour it in slowly. This allows the coolant to get in the nooks and crannies and purge out the air. Once you fill the coolant enough to get to the cap, give the coolant pipes a squeeze, this help move any air around and out of the system. Soemthing i have done and im sure a few other have, is to start the bike. This circulates the coolant and air round the cooling system pusing the air around and up thorugh out the top of the radiator where the cap fits.

As for the amount, just ensure you have at least hat amount to put in, if it slightly more it doesnt matter. Typicaly, bottles come in 1l sizes so you will need 3l and that should leave you with plenty spare should you need it. If it states 50/50 in the manual, stick with it. No point in changing it.

Re: Coolant refill help

Posted: Tue Mar 19, 2013 10:16 pm
by banner001
the word "coolant" is a misnomer, its actually an antifreeze/corrosion-resisting fluid.

i run 60% water/40% coolant in summer and 50/50 in winter.

pure distilled water has one of the highest specific heat capacities of a fluid, polyethylene glycol (PEG, the major component of antifreeze) has around half the SHC, this means that if you heat a sample of water, and a sample of polyethylene glycol the temperature will rise a lot faster in the PEG solution than in pure water...the best "coolant" for an engine is just that, distilled water...but it will freeze, and gives no corrosion resistance, thats why you add "coolant".

if water has an efficiency of 100%, then at a temperature of 94C a water/PEG mix of 50/50 is 86.5%, whilst 60/40 would be 90.5%, although its boiling point (unpressurised) is slightly reduced from 107C to 104.5C...but this is mitigated by the fact that we run a pressurised coolant system, so the boiling point will be higher than stated here (coolant at a radiator pressure of +14psi will boil at 125C for 60/40 and 129C for 50/50).

its also good for -25C at 60/40, as opposed to -37C for 50/50...but its not going to make much difference whether you use 60/40 or 50/50 throughout the year.

so in winter when i want my engine temp to raise quicker, and due to the colder air it will naturally cool better i run 50/50, in summer when its "hot" weather i dont need my engine temp to rise as quickly, and i want it to cool better, and night time temperatures aren't that cold, i run 60/40.

Re: Coolant refill help

Posted: Wed Mar 20, 2013 5:55 pm
by ryan78
Thanks for your help guys, will refill the system soon as i have chance, two young kids means i dont have time in the evenings!