Coolant leaking at cilinderhead pipe to thermovalve

[lars]

Last time i checked valve clearance i had the same leakage at the same point. After tightening the bolt it was fixed but you don't suppose to tighten it more as 10nm

today is chanced the distribution chain and during heating up the engine to refill the coolant I noticed the same leakage. I fitted a new O-ring (default ring not original yamaha) but still leaking!

coolantpipe.jpg

Does anyone know the dimensions of that ring (diameter and thickness) or is there a other solution??

[Mincehead]

Are you talking of coolant stub pipe 20 and O ring 21?
I recently replaced my terribly scabby one and it`s a good job I did because the pipe actually broke up it was so fragile!
Absolute barsteward to get out of the head too,the alloy/steel interface between pipe and head had caused a lot of corrosion.
I had to break the pipe in half,then use mole grips to grip what was left before using a range of punches to `persuade` the blighter out.
Have you had the pipe out before?
The Yamaha O ring for that point was only around a couple of quid here in the UK,I smeared the replacement stub with copper grease and also wiped a thin layer of clear silicon around the O ring before fitting it,the coolant system is pressurised so a weak seal and the nature of antifreeze means leaks are always possible.
Mine has behaved impeccably though,no leaks at all.

[lars]

Yep that's the one!
It's a stupid construction, only 1 bolt to make the seal!

I have had it out before, during valve clearance adjustment. Mine is still in good condition only the seal is bad.

Can you remember if it was a extra thick O-ring or just a regular one?
I'm afraid my local yamaha dealer doesn't have it in stock, and ordering it will take 2 day's.

[Mincehead]

Extra thick?
O rings are manufactured to standard sizes generally but obviously there are material specification differences depending on where it`s used and there can always be specials just for certain manufacturers of specific areas.
I didn`t really pay too much attention to the Yamaha original but to be honest I doubt it`s any `thicker`.
What a new one will be though is far more pliant,soft and compressable,they do harden as the ethylene glycol slowly affects them over time.So,you going to wait two days then or is it silicon or bust?

[lars]

I have seen some thicker ones in the past (i work at a car parts shop).
for example the O-ring (the small one) in the oil filter cover is pretty thick.

I'm going to replace the O-ring again today and maybe put some extra liquid sealant on it. If that doesn't work i'm going to order one asap. Superbike weekend is coming up and i want go with the TRX to watch it

[steve speed]

just make sure the inside of the head is clean ,, it should be a tight push fit ,, and use a bit of silicone sealant , that should do the trick

[lars]

It's fixed, fitted a new O-ring put some crease on it and it's sealed.