Kawasaki Sportsbike Riders Club - Australia - Online Forum

Got a leak coming from a radiator hose. Just wanted to run it past you guys in case there's a chance it's a rooted water pump instead - because replacing that hose is going to be a nightmare and I'll probably just take it in to a mechanic.



The leak is coming out just to the right of the circular clamp that holds the hose on. It doesn't leak when I squeeze the radiator hose, only when the engine is running. It starts to leak very quickly after the engine is on, but never more than a very slow drip. You can see the line where the clamp used to be - I moved it closer to the pump to try to cut it off, but this didn't help.

I'd say it's got lupus.

you're going to hate me for saying this.

but while the hose might be a bitch to get to, it will also be the cheapest option to replace and see how that goes.

It already looks like the hose clamp on that hose has been loosened and retightened, so it could be that the hose has slipped or the clamp has or something.

The fact that it only happens when running seems to point at a seal in the water pump, but does it happen immediately from start, or does it start when things start to get hot and expand? If it's the second case, my guess would be a worn pump. how about after the engine is switched off? Does the flow stop immediately, or does it continue for a while?

It could be the pump cover gasket also. Have you pulled the hose and hose clamp off to inspect it? Neither replacing the hose or the water pump gasket, or even the water pump, is no biggie. If it is, just buy the parts and bring it over next weekend when I'm home and we'll do it!

id replace the hose, the o ring on the water pump and the hose clamp and be done with it. Also inspect the pump impellers by taking the front off it and giving em a bo peep.

My ZX9R was leaking in a similar spot, also only when running. In my case, tightening the loose hose clamp fixed it. If that's already been done, I'd take the hose off and look at the water pump outlet - it could be corroded or mashed to the point it's no longer sealing. If that's ok, I'd replace the hose.

as it turned out my hose clamp was a p.o.s., replaced it, still leaked, clamped the hose on in a different position, no worries, the clamping area was kinked in a 15' angle and only clamping at one exact spot would stop the leaking.

then i replaced the headers and had a world of hurt with tubing o rings onto the heads hardening and no longer sealing. THAT took a while to unfark.

also from what i've seen of the waterpumps, if its leaking, the only place aside from through the front plate o ring/a crack in the body of it, the only place for water to go is through the sealed bearings on the drive shaft going into the crankcase. I suspect that it'd be a similar case for you, and would likely not be a main shaft seal problem.

leaking when running, kinda suggests that it leaks under "pressure" or when heated, i'd be chucking a new clamp and hose on it. or even just a clamp and see if that fixes it.

nothin like an easy fix


worst case, buy some sticky tape.

coz my friend, there is nothing that stickytape cannot fix!


theres also an old wives tale (that i've actually seen work)
you chuck pepper in the water, and some how fixes it. (but probably not good for the rest of your engine.)

wattie, that's because the peppercorns gravitate to the leak and swell getting stuck, thus blocking the leak.

it's an old bush mechanic temporary fix for a hole in a radiator.

Sweeeeeet, that pepper thing sounds cheap. I'll throw some salt in too for that British touch.

Wouldn't that start the bike sneezing???

Not if you throw some Zyrtec in the tank...

Heh heh cheers guys, I've booked it in to Doctor Balls for a good thorough how's-yer-father. The other end of that hose just looks like too much effort to get to, and it needs a proper full service and tune anyway. I might get Balls to advise on jetting as well while they've got the thing apart...

oh your poor bike, its going to the drs

hope its only as simple as the hose clamp or the hose has just buggered itself and doesnt like having pressure put through it.

Just an update for the interested - the water pump itself was blown, Dr. Balls put a second hand unit on and it seems to be fine now.