Coolant Flushing

[Ingah]

A little while ago i bought some radiator coolant flushing liquid from Halfords (something like this http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_productId_166188_langId_-1_categoryId_165750), as my CB5 has been getting very very hot whilst in traffic (had to stop the engine a couple of times to prevent it overheating) and the fan doesn't always come on to keep the temp down.

The bike is very old and was very run-down before i started fixing everything, so it's probably just a case of old coolant, so i'm finally getting around to replacing it.

I'm planning to use that flushing stuff to clean out the coolant system, and instructions are to drain the system, refill and add the coolant flushing stuff, run the bike as normal for 20-30 miles, and then drain it again before refilling as before.

I just wondered if anyone knew if it is safe to:

1) Run the bike with the coolant flusher in it for longer distances (nearer 50 miles - 2 trips of 25 miles) as then i wouldn't have to go on a needless ride (fuel is expensive and i've got stuff to do!)

2) Leave it for about a week with the coolant flusher in it, before draining the system again to fill as normal (the bike is kept outside, i can cover it if necessary). I'm worried about it potentially freezing up and cracking open the coolant system, and also the possibility that the flushing solution shouldn't be in there for so long.

And also, if i'm supposed to put in water with the coolant flusher, or engine coolant, as the instructions don't make that clear?

[Ant132]

I would guess that the guideline of 20-30 miles is a minimum guide. I.e. use it for at least this time or else it may not work. So 50 miles would be fine i would have thought.

Also i would say you pour the mix straight in, they usually are.

[Colin the Bear]

If it's overheating in traffic and your fan doesn't come on, assuming the fan itself isn't the problem, I'd be looking at the sensor or, maybe wire the fan direct through a switch.

It won't matter how clean the system is ,if the fan doesn't work , it will overheat.

[Ingah]

On closer inspection the instructions said that i could let the engine warm up and then run the bike at a fast idle for 10 minutes instead, so i did that. I just did it all in one big session. Also, i decided the coolant flushing stuff should be combined with water (Haynes agreed), so i did that. It all got drained out afterwards so no point wasting good coolant!

The fan will come at a later date. The CB500's are supposed to run "unusually cool" which now seems to be the case with the shiny new coolant The old coolant looked a little bit funny anyway, so i'm glad to have got rid.

From previous investigations i found the fan itself works OK, it just doesn't always automatically come on when it should (not that this should be often anymore). I'll add the fan to my everlong list of things to do though.