TOPIC:

Hi there,

My coolant tank is busted at the rear. Getting a new tank is proving problematic.

Is this tank actally under pressure when the bike runs? I'm thinking of cutting the tank in half and 'plastic soldering' a new plastic plate at the rear (where my finger is in the pic), but obviously that is not a good idea if the system is under pressure and if all of the tank volume is needed to run the bike.

Paul

There is a pin hole just under the metal near the cap.

As I understand it - this is to allow coolant to be sucked from the reservoir into the main cooling system. I still don't get how that works but if it wasn't for the pin hole there would be a vacuum that would prevent the main cooling system from filling

I think that breakage occurs when someone forcibly removed the lower air box without moving the expansion tank first

Thank you.

Right, if there is a pin hole in the tank it can't be under pressure... unless the hole is a 'one-way' vent (in, but not out).

I shall try to find it and if it is indeed just a 'regular' small hole then that tank cannot be pressured.

But as you I am struggling to understand how it can then top up the system and how much volume is needed for that function.

Paul

Hi, the tank is vented through small hole under the metal cover to atmosfere. The radiator cap has two valves in it, one to allow the excesive preasure to expell and the other one to allow to pull the liquid in to the system when the engine is cooling down but normaly the preasure is almost in ballance unless you venting the air out of the system. On my bike i see a change in level of the coolant about one cm. higher when hot.

Thank you.

That confirms the tank is not under pressure.... the vacuum from the radiator sucks water from the tank into the radiator, from the bottom of the tank.

If you only see a one cm level change, then not the whole volume is needed, so I should be able to manage with half a tank.

That said, I'll try it. This tank is fubar anyway, so nothing to lose as long as I keep an eye on the levels once the bike is running.

Thanks all!

Paul

P.s. and just incase you were wondering, the air box was already gone when I got the bike... Wasn't me!

Since all else was already explained, I just mention that there is a good overflow tank on Ebay now.