Plastic reservoir with a cap behind rear shock (2001 Fazer 600)

[vladman]

Hi, I was poking around the bike and for the first time (in 6-7 years ownership) noticed this!  :rolleyes

I have no idea what it's for.  It's NOT the rear brake fluid reservoir (I know where that is).  Can anyone advise on what it is?  I can't see the level in it (it's got the usual max and low markers), it's quite dirty, but I think it's low, or even empty.  Wouldn't be surprised, as I've had the bike for a long time, and never even knew this thing was there!

I can post a pic if my description is not clear.

Thanks!

[Foxwood]

Sounds like the coolant reservoir to me. 

[Dead Eye]

Yep, that would be the coolant overflow reservoir

[vladman]

Foxwood and Dead Eye, thanks for the speedy replies.

At the risk of sounding like a total noob (which I'd like to think I'm not), isn't the coolant topped up at the front, at the radiator?  And if it's some sort of overflow reservoir, do I need to ever pay attention to it, and fill/top it up with anything, or perhaps empty it?

Cheers guys!

[Foxwood]

Yes, the coolant is filled through the radiator cap since that is the highest point in the circuit. Well the manual says the coolant reservoir should be filled to the maximum level, so I'm bound say that it does have some meaning in the circuit. If you haven't done anything to the coolant for a long time (X years?), I'd suggest draining the old coolant, flushing the system and filling it with new coolant.

[Dead Eye]

I believe the reservoir is designed to catch any fluid that overflows from the thermostat if the water gets too hot and begins to boil and expand. The reservoir allows space for this expansion and for the water to cool

[darrsi]

There is an upper and lower level on that expansion tank which you should keep an eye on every now and then as it's a quick way to see if your coolant system is all good.


When it's all good the fluid should more or less stay between those levels.


If the system has blockages or scaled up pipes for example, it will not flow properly, the bike will overheat, boil the fluid, then dump it out of the overflow pipe onto the floor.
When the bike cools right down it sucks fluid from the expansion tank back into the general system.
Then you will see that your levels are wrong and you have a problem, and in this case you will need to buy Radflush and give it a good descale.


Having low levels is bad enough, but not knowing you even have an expansion tank is a bit naughty to be truthful, because unless you top up regularly from the thermostat end under the tank, then you have no idea what coolant levels are in the bike, so it's very important to keep an eye on that expansion tank lower/upper level. 
Don't go above the upper level as if the bike gets very warm it'll just dump it on the floor.


I would seriously suggest you do a full Radflush, i reckon the bike will need it.
I personally normally leave Radflush in for a couple of days to let it warm up and cool down a few times for a proper descale but i wouldn't recommend that in this weather as you will only have water in your system, rather than coolant, so just follow the instructions.


Basically, with just water alone in your bike, combined with this weather, you'll have a really fast kettle.  :lol


After using the Radflush, then giving it a good flush out with a hose, get a good premixed coolant and top up from under the tank and the expansion bottle, then hopefully your bike with give you a big sigh of relief 




This is the coolant i use  http://www.ebay.co.uk/itm/Motul-Motocool...53f980a3e2

[limax2]

As others have said it is an expansion tank. When the engine heats up the coolant expands and has to go somewhere, hence the expansion tank. When things cool down some coolant is sucked back into the engine. The coolant is topped up at the cap on the thermostat housing, which is under the fuel tank, but the expansion tank should always have some coolant in it.
Also, when changing the coolant there will often be a bit of air in the system and in use this will find its way to the top of the thermostat housing. On heating up this air gets pushed into the expansion tank and is replaced by coolant when the engine cools down. After that the level should stay the same other than being higher when hot.
Unlike the engine and radiator system the expansion tank does not become pressurized when hot, hence only has a flimsy plastic cap.

[vladman]

Everyone, again, thanks very much for the detailed replies.  I know the coolant was changed and the system flushed (at my request, as I had no idea when it was done prior to that) about 2 or so years ago.  Changing coolant is one of the few things I've never attempted to do myself on my bikes, I think I got scared away from doing it when I read something about air getting into the system and being a pain to get out.

I'll have another good look at the level, and then take it from there.

Thanks again.

[Dead Eye]

Its not like your brakes, a bit of air in the system isn't going to hurt and it will work itself out fairly easily

[darrsi]

Some peoples idea of "flushing" the system is simply draining the coolant then sticking a hose down the radiator cap for a rinse out.
This is not the same as using Radflush.

Using Radflush is similar to descaling a kettle, and will unblock your waterways creating a healthier path for the coolant to flow, and making a much more efficient system.

[vladman]

Thanks darrsi, I'll definitely look into it, sounds like the bike could use it, simply because I don't think it's ever been done before (this Radflush flush) and it's a Y reg...

[darrsi]

Thanks darrsi, I'll definitely look into it, sounds like the bike could use it, simply because I don't think it's ever been done before (this Radflush flush) and it's a Y reg...

It's certainly worth doing, even if it's just for the sake of learning a bit more about your bike, and also so you have a definite date that it was properly flushed out.