Random Coolant overflow - Curvy.

Went for a 200 mile jaunt on Sunday, got home , no problems..

Tuesday night went out for about 35 miles after tea, some A roads, some urban, some motorway, but when I got home I found coolnt dripping from the RHS where the engine bolts onto the frame, dripping onto the hot exhaust (lot of steam) ... probably no more than an eggcup full onto the pavement, maybe double that if you include the steam ...

Is there a coolant overflow at the back of the engine?
Oil looks clear (ie no emulsion) in the sight glass .. any ideas ..??

Edit - sorry, its a 99 curvy with 29000 on the clock

Is your coolant level ok? could just be expansion overflow.

Could be like Bluefish has suggested. It shouldn't overflow for no reason though. A simple and fairly common cause is a bit of crud sticking in the valve in the radiator cap allowing very hot (above 100 degrees) coolant to flow straight into your overflow bottle and out of the top (as it's now boiling due to being at atmospheric pressure).

Or it could simply be leak!

Let us know what you find and importantly check your coolant level before you ride it again.

[Sid Squid]

The engine bolts to the frame in more than one place. Where do you mean?
The coolant overflow is the tube clipped to the rear edge of the clutch case, (shared with tank filler well), coolant will drop on the floor below and just to the front of the right footrest - assuming all the bits are there and correctly fitted of course.

First thing to check is the radiator cap as Monkey boy says. Most people don't realise it, but the cap is not simply a lid, it's two valves, the sealing of which is vital to the correct operation of the cooling system.

[timwilky]

In a previous life I used to do engine cooling tests. One such test was a hot shutdown.

Run the engine hard for a sustained period and then bang off the engine. Measure the coolant loss.

Expansion tanks serve two purposes, firstly to allow coolant water to be contained. and then to host the filler cap that is pressure set to release to atmosphere if the coolant pressure builds up beyond the cap setting.

So depending upon how you have been riding, if it is very hot, let the bike tick over for a few minutes to allow the temp to drop before shutting it down

thanks for the responses, chaps .. first chance I have had to look at it was this evening :
timwilky .. If the engine is hot, I have always let it idle for a short while to allow it to cool anyway, but I didnt realise that the filler cap was pressure set.
sid squid / monkey .. the overflow pipe is there all in one piece, connected to the tank filler well, and yes, the coolant loss appears just by the right footrest - again, I didnt realise that the rad cap was too valves : thats a possibility then (is there a way I can check these valves are working properly? like drop it in a pan of hot water or something?) - certainly worth a wash out though by the sound of it
Bluefish .. tried to check the coolant level by peering at the expansion bottle (whilst cold) .. but I cant really see if its full or low.. tried topping it up (tank up, plastic bung removed etc) - put about 100 ml in before it overflowed the top of the filler neck.. so thats why I couldn't see the level in the exp. bottle, as the level was too full ?

siphoned excess fluid out to below the overflow pipe (but still well above the 'full' level on the bottle), replaced the bung and ran the engine - as it gets warm, it is dripping coolant (as coolant expands), increasingly more as the engine gets hotter, then the fan cuts in after a few minutes and the the dripping stops. After the fan stops, the dripping gradually starts again.. (ps, when the fan comes on, the 'hot' warning lamp remains unlit)

SO ... my conclusion is (i) I have too much coolant in to begin with, and (ii) I am going to take the rad cap off, wash it through just in case there is some crud in there, and put it back again. Then on Sunday, I'm off to Newcastle and back, so we'll see how it goes !!!!

Does that sound reasonable ?

[garynortheast]

I had this with my 400 gixer a couple of years back. It was a weakened spring in the rad cap. I solved the problem by buying a brand new Suzuki one for around £15.

My bike was doing the same thing. I dropped all the coolant from the radiator, hoses and expansion tank. Filled just the the rad back up and ran the bike for say 15-20 mins with the cap off and give the bike a few good revs so the coolant circulates, keep an eye on the coolant level in the rad and make sure it doesnt go to low, after you have done that then leave the engine to cool with the rad cap off then top the radiator up if it needs it then the expansion tank, the expansion tank literally only takes a very small amount I dont even think its 100ml from empty.

Right ... had the cap off this evening, and there was a build up of crud especially sround the small (outer) rubber seal .. something akin to limescale .. and to a lesser extent on the larger rubber seal in the cap body.
Cleaned both seals up, replaced cap
Off to Newcastle tomorrow (temp at 7am will be 0 degC ..!!) so we'll see how it gets on ... I'll let you know !
Cheers
Chris

[yorkie_chris]

Originally Posted by timwilky

Expansion tanks serve two purposes, firstly to allow coolant water to be contained. and then to host the filler cap that is pressure set to release to atmosphere if the coolant pressure builds up beyond the cap setting.

Not on SV. By that definition the rad is the expansion tank.

Rad has cap on top of it with spring loaded valves in, 1.1/1.2 bar I think. Then pipe goes to tank which is at atmospheric.

Coolant expands, goes into tank, coolant contracts, sucks coolant back in.