Right, having drained the oil and coolant to tighten the crank nut, I now find the coolant comes overflowing from the cap whilst running after being sat still for a few minutes; appears fine when moving

What is known:
Previously had overheating issue rectified by a new coolant thermometer sensor,
Radiator cap is good, new one used for a few months now,
Water pump wasn't opened during crank nut procedure, just removed,
Drained coolant was clear and as new when drained for the crank nut and again when drained today when refill attempt two was tried today when being suspicious of trapped air,
No warning light coming on where the bulb is good and the temp sensor was replaced only one or two months ago.

If there's more to add I'll add it, but any help would be more than welcome!

Bike is a 2008 MT03 (xt engine yadayada...)

Thanks

Ok, could someone please confirm the position of these hoses on your bike (see pic)? Surely the expansion bottle should be attached on the higher point above the pressure cap base?

https://drive.google.com/file/d/0B8x...ew?usp=sharing

I had this, maybe you can find similarities:

- overflow of coolant from the hose of the radiator
- the reservoir was filled up, but the radiator empty. Can you check the level in the radiator?
- engine overheat turned on. Just continuously filled up the radiator and could drive another 400km.

Solution: the spring of the cap of the radiator was too weak. So couldn't hold pressure and lowered boiling temp of the coolant.
So, got myself an new spring and put it in the cap. Never lost another drop.

Cheers chap, I replaced the rad cap not to long ago, but this afternoon after some hose realigning, all seems good now. Thanks for the input

Well done!! I love the MT03, they sold loads here in Italy and they are a great all round bike.

__________________
(Now sold on, sob) 2011 Blue XT660X with gold wheels, was 26,500 km.
Engine mods: K&N Stage 1 filter, DNA Stage 2 filter, snorkel removed, Kev fuel mod fitted.
Plus: smoked Puig screen, Yam aluminium sump guard, Yamaha / Acerbis handguards, Givi Trekker aluminium side cases, Leo Vince X3 cans plus Kev front fork mod and Fender Xtender. Just fitted Michelin Road Pilot 3 tyres.

SOLD the XTX for a Super Ten 1200. And just bought a Raptor 700 so staying on here for some tips....