[fewtrees]

It's another one of these...

Just had the Cylinder Head Nuts TSB done on my '04 950 Adv along with a coolant change and now have a bit of a problem. The bike was completely fine before

After a bit of "spirited" riding I park the bike up and turn the engine off - coolant spews from the coolant overflow, then the level shrinks back down and disappears or is very low (lower than min). When I started the journey the coolant level is ok - not above max..

After this I cleaned the rad cap and tried running the engine for a while without the rad cap on to see if air comes out..

When the engine was cold and revved a bit, the coolant level rose in the rad - if I'd kept reving it would spill over.. Is this supposed to happen - OR - Is this a cylinder head leak into the cooling system because there's a gap when it's cold?.... because....

When the engine was warm/hot and revved a bit, the coolant level dropped in the rad. Eh?

Hmm, by this time I can now see the coolant is getting damn hot and the coolant level in the rad starts bouncing up and down so I think, gotta turn the engine off..

I turn the engine off and whoosh - coolant shoots out the top of the rad and lots of it.. :wanker: I know :dozey:

Now do I take this bike back and say it's got a cylinder head leak? Whadya think?

 

[afw38]

Did the person who filled it with coolant follow the correct KTM procedure to ensure all of the air was eradicated/

 

[fewtrees]

I'd hope so - it was Route 55 Motorcycles in Queensferry my nearest KTM dealership that did the work..

 

[mooky]

Nope, they havent done it properly.

The rear cylinder passage is a bit of a faff to bleed. You have to raise the front wheel about 1-2 feet - or else an air bubble is left.

What happens then is as soon as you stop your bike, the coolant stops flowing - and the air bubble is now quickly heated by the hot cylinder head - it expands, forces coolant out... then later it cools, and sucks coolant back in.

Raise the front wheel, rock the bike side to side & that should get the bubble out. And ring them and tell them to do it properly next time.

 

[fewtrees]

I'll give that a whirl - see what happens :smile:

 

[fewtrees]

Thanks for the advice so far

Right - I put the bike on a steep slope and swung it side to side... Not one air bubble..

I started it up without the rad cap on and swung it side to side - nothing..

I let it run for a while and let it heat up, bunged the rad cap back on and let the fan come on, then go off again.. Then turned the engine off...

Last time, the coolant overflow level rose and eventually coolant.. overflowed.. but this time - it stayed pretty much rock solid.

So I took it out for a short spin and after that watched the coolant level when I turned the engine off - still rock solid..

It seems that allowing the pressure to release violently has shifted some air..

If you think this needs more attention then please say...