Coolant flush


5 replies to this topic
  • chrispa

Posted July 03, 2011 - 04:04 PM

#1

Guys,

Got to the track on the w/e, noticed the coolant was a little low on the YZ450F (2008), so decided to top up with tap water (nothing else around), about 250ml (cooling system has a 1 litre capacity) and rode for about 2.5 hours without any boiling/overheating. Level stayed constant throughout.

Should I now flush the coolant and replace with de-mineralized water? The manual states a coolant/water ratio of 50/50. Shops also sell pre-mixed coolant (ie. http://www.superchea...053#Description). Would this stuff contain the right mixing ratio? Or is it best to buy some demineralized water and some of this stuff: http://www.superchea...034#Description and mix it myself?

Also out of curiousity, how long does tap water take to start corroding the internals? When flushing the radiator, is it just a matter of draining, and pouring tap water into the radiator until it's fully flushed out of the drain bolt? (clear water coming through), then topping up accordingly?

  • brentn

Posted July 03, 2011 - 04:09 PM

#2

It would take a bit of time before deposits start to form.

Since you still had coolant in there, and only added a bit of tap water, there is really nothing to worry about.
For piece of mind though, yes I would drain the coolant, fill with bottled water that you buy to drink, run the bike for a little bit and drain. Replace with 50/50 of your favorite coolant brand. If it's premixed great, if not, mix 50% with bottled water.
There are people who will say that you should not use ANYTHING but bike coolant, but it's all bullshit and the more recent bikes have water pump seals that will stand up to any brand coolant. On my old 05 yz250 I was using prestone 50/50 for at least a year with no problems at all.
On my new 450 I'm using blue ice.

  • brentn

Posted July 03, 2011 - 04:13 PM

#3

Also, just FYI, antifreeze is used in motors for two reasons

-One it doesn't freeze and crack the coolant passages
-Second, it is sort of a lubricant for the water pump seal, and mostly will prevent deposits from forming and prevent rust with cast iron blocks.

IT does not have a better thermal conductivity than water, this is why you don't want to use 100% antifreeze mix. Water has the best thermal-conductivity over anti freeze, so really running 100% would be the best for heat dissipation. But you don't want to do that either due to the deposits that can form and of course when the temps drop below freezing and the bike is stored.

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  • grayracer513

Posted July 03, 2011 - 05:15 PM

#4

Also, just FYI, antifreeze is used in motors for two reasons

-One it doesn't freeze and crack the coolant passages
-Second, it is sort of a lubricant for the water pump seal, and mostly will prevent deposits from forming and prevent rust with cast iron blocks.

IT does not have a better thermal conductivity than water, this is why you don't want to use 100% antifreeze mix. Water has the best thermal-conductivity over anti freeze, so really running 100% would be the best for heat dissipation. But you don't want to do that either due to the deposits that can form and of course when the temps drop below freezing and the bike is stored.

It does, however, raise the boiling point from about 230 (straight water under a 1.1 bar cap) to around 265-275 (50/50 under a 1.1 bar cap).

  • ttr250dude

Posted July 03, 2011 - 08:46 PM

#5

Personally, i wouldnt run the dirt cheap stuff. But thats just me. I've heard of guys running coolant for deisels to prevent boil overs. That stuff doesnt keep the engine cooler, it just raises the boiling point, it doesnt solve the cause of the problem. Alot of of guys say Engine Ice actually keeps the engine cooler because it transferheat better or something like that. I havent boiled over while using Engine Ice.

  • chrispa

Posted July 04, 2011 - 02:57 AM

#6

I cannot find Engine Ice at any local bike/automotive shops near me, I'll go to the bike shop and ask what they recommend...

If a bike has corrosion within the cooling system, this will show up when you flush the coolant eh? ie. you'll see deposits floating around at the top or within the fluid you drain out of the bike...

Same goes for rust, and rust will be built up around the radiator cap? I'm new to the maintenance world on bikes, just for my own piece of mind as I plan to purchase another second hand bike soon.

What about magnesium? Are there any other signs to a bad cooling system?

Edited by chrispa, July 04, 2011 - 03:32 AM.






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