RD125LC Radiator Cap Question

[looey]

I have a bit of a funny with my RD125LC (well a few actually but one at a time :

Basically the bike runs fine, doesn't get hot however long you ride it, doesn't actually use any water but it keeps pushing coolant into the expansion tank from the radiator.

Before I start a run I put the level in the expansion tank on the lower mark and the rad upto 1 in from the top. When I get home (and it doesn't matter how long I ride it, even for an hour), there's always about an inch or 2 of coolant gone from the rad and the expansion tank is about 1/2 full.

If I then suck the coolant out of the expansion tank until it's back down to the lower mark (turkey baster ;D) and put that coolant back into the rad then I am exactly at the same levels in both the tank and rad as before I started.

I'm sure if it was head gasket of anything like that the problem would get worse and worse the longer I rode until it eventually spat coolant out but it doesn't

I'm pretty sure that either the rad cap lower seal is knackered or the spring is too weak which is then letting coolant past prematurely and down the pipe to the expansion tank.

Any one got any other ideas or a good rad cap I could buy to try ?.

I'll get it all sorted in the end !.

Cheers

[carlos]

Yup, liquid expands when hot, and contracts when cold!

[looey]

Yeah cheers chaps but this is more than that. I have a 350LC and a YPVS and a GSXR1000 and when hot they all expand a bit of coolant into their expansion tanks then when they cool it gets sucked back in, so when back to cold the expansion tank level is back as before and if you take the rad caps off there is still coolant upto the neck of the rads.

The difference here is that this is adding 2-3 inches to the expansion tank once it's hot but it doesn't go back to the radiator when it cools down. So once it has cooled down the expansion tank is up 2-3 inches up and take the rad cap off and the level has dropped just below the top tank area so it looks like there's none in there ?.

What I haven't done is ride it again at these levels to see if it stays the same cos there is no longer enough coolant in the rad to push any more out to the tank ?.

I'm sure it's not head gasket cos theres deffo no excess pressure building up in the cooling system ?.

I will try it with my 350LC cap on as well.

[looey]

Yeah I'll try it with the 350LC cap and let you guys know if cures it or not.

Aug 13, 2009 20:14:40 GMT 1 garyrdrobbo said:

you may have a duff cap then mate....350 lc one should help you narrow it down..