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coolant level

10K views 17 replies 10 participants last post by  notacop 
#1 ·
i was curious about the coolant level. what im looking for is someone who has the dvd i guess, that says how much coolant the bike holds.

i know the area to check the coolant level is supposedly an overflow tank. but if thats true, why does it have a MIN MAX marking? is coolant supposed to be in there?

last time i watched someone drain my coolant they unclamped a hose, drained it, then filled it back up through the main opening, with the metal cap. they didnt touch the overflow tank.

anyone have some pointers and facts about the overflow tank, and the quantity the bike is to hold?
 
#2 ·
Don't think of it as an overflow tank. More an expansion tank.
The bike cooling system right to the radiator cap is completely filled with no air in it.
As the bike gets hot the fluid expands. This increases the pressure ad therefore the boiling point. Allowing the bike to run at above 100 degrees without boiling up.
However any excess pressure must have somewhere to go so it bypasses a value in the radiator cap and gets pushed up the small rubber pipe to the expansion tank.
As the engine cools the pressure in the cooling system will drop and draw water back down the small black pipe from the expansion tank past the radiator cap seal and into the system.
Experience has shown that filling the expansion tank above min when the engine is cold (and the coolant system has drawn back the maximum amount of fluid it will) will result in more fluid being pushed into the expansion tank when the engine is hot than the tank can hold and it will overflow.
So when the engine is cold the expansion tank needs to have min level of fluid.

Also note if you try and remove the radiator cap without clamping the small black tube to the expansion tank the expansion tank fluid will drain out via the radiator opening.

Finally on the cooling system if you suspect air is in the system there is one bolt on the water pump indicated by an arrow on the casing that is used to bleed off air.
 
#15 ·
[...]Experience has shown that filling the expansion tank above min when the engine is cold (and the coolant system has drawn back the maximum amount of fluid it will) will result in more fluid being pushed into the expansion tank when the engine is hot than the tank can hold and it will overflow.
So when the engine is cold the expansion tank needs to have min level of fluid.[...]
FWIW my 09 coolant has always been midway between min/max and has no overflow issues so there doesn't appear to be a hard and fast rule on this. Having said that, Pat's suggestion is best followed as it will always be OK.
 
#6 ·
My question is: has anybody seen the collant level through that slot? I had to take of the top right part of the fairing to be sure I was seeing the level correctly. What is the secret to this?
In theory if you shine a sod off big bright light up into the bottom of the coolant bottle you can see it through the slot.
But I never bother. I check the fluid when the fairing are off a couple of times a year and other than that I rely on the fact that the temp gauge is happy and no fluid has leaked out.
 
#7 ·
+1 on what Pat says.

Its a snap to take the fairing off to check.

And keep the fluid to the MIN level of the tank, I had major engine spray from the coolant bottle overflowing on hot days and hard, spirited riding when the tank was close to the MAX mark.
 
#8 ·
i dont have any fluid in my overflow tank to check on the min line, thats why i was wondering. so this makes me want to drain everything and put the proper amount in, since just trying to put some in will not give me a proper amount...i dont know how much is in there as is.
 
#16 ·
It works!


I put 30,000 miles on my F800 and I thought I had tried everything but I must not have tried this. I went to the garage and it took some trying to find the correct angle but when you look under the headlight with your head near the front fender and your body on the right side of the bike you can see the fluid level. Now, I didn't see the Min. and Max. markings. I'll just make some lines on the plastic tank next time I have the side panel off.
 
#11 ·
Make up some fluid to the correct ratio of antifreeze and water (don't go stronger than it needs to be as it doesn't cool as well) in a separate container.
Remove the rad cap and let any excess overflow (there maybe some in the expansion tank pipe)
Top up the radiator till it's almost full.
Start and run the bike. Watch the water in the radiator and the temp gauge. As the temp rises the water will start to move in the radiator (indicating the thermostat has opened and water is flowing) slowly top up any drop age in level.
When the rad is completely full screw the cap back on.
Top up the expansion tank to the min level.
Let the bike run another 5 mins or so (to pressurise the coolant system) Loosen the marked water pump housing screw until water (and no air) squirts out.
Tighten the screw and turn off the bike.
Leave the bike over night to cool and confirm the expansion tank is still at min (top up if not)
Re-assembly fairing and take for a good sporty run. Keep an eye on temp gauge.
When you get back let the bike cool down and re-check expansion tank.

Well that's what I'd do but what do I know :rolleyes:
 
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#17 ·
An update on checking the coolant level, two things I'm using. First with the bike on the center stand (before setting out on a run) just press down on the seat to shake the bike enough to make the fluid level move up and down and you can see that movement through the slot, after a few runs you get a sense of the appropriate level that way. Second I now have a 'pencil' torch with a small light on the end surrounded by a rubber sleeve, with the light 'on', pressing the sleeve on the base of the bottle (easily done on the ST from behind the fairing) illuminates the fluid in the bottle enough to show the level.
 
#18 ·
You guys really check the coolant level? Like the oil level, I don't check that between the 12K dealer services. Let them worry about it.
Only time my coolant leaked was when the dealer overfilled it and left the cap loose.
There are a lot more important things to lend my attention to, oh look, a squirrel!
 
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