Blown head gasket

[Jakobi]

Well,

After some reading and posting a few questions on older threads I believe my inner o-ring has either been pinched or isn't sealing properly.

The bike appears to run quite well and still produces good power however there is a slight amount of greasy oil in the coolant. The coolant bubbles with the bike running and the rad cap off, or else you see it bubble into the resevoir. It actually hasn't used any coolant which I find suprising to say the least. Its like it only leaks exhaust out into the coolant, but not the other way. Pretty bummered out as I've only put a few kms on the bike since getting the S3 head on it and its time to pull down and check again.

I'm really hoping its clear where the leak has happened and that it is the head and not the base gaskets. Would this cause the same thing to happen?

Argh Argh Argh! The joys of riding

[motogroove]

I am certainly not an expert, but I don't think a bad base gasket has access to your coolant. The one way flow of the pressure seems to confirm it's not subject to crank vacuum.

And, seeing your other recent posts, I'm not sure a water pump seal would explain the bubbles. And with that, we'd expect some coolant loss, I think.

So, I think you are on the right track. At least it's sort of the easiest of the three to check, I guess.

But, I'm just guessing because I can't sleep.

[Jakobi]

I think we're on the right path too. On the bright side if I am losing compression under/over the o-ring and into the coolant I can only expect more performance gains once I get it fixed. Bike has been running like an absolute dream too. Got some new o-rings on order and will have it down for inspection through the week.

Whats everyone elses opinion? GMP? You know these bikes better than anyone

Any idea what to look for when the head is off regarding the possible cause of the leak?

[Bailey28]

Ahhhh that stinks... My coolant tank bubbles a lot when idling or revving it a little in neutral. I haven't been into the top end though.

[GMP]

While it would sure seem likely that the head o-ring was pinched, what does not fit is the fact that the bike runs well and does not release the rad cap and blow coolant from high pressure. Try to determine for sure if combustion gas in what is bubbling in the rad. Don't mistake normal turbulence in the fluid for this. There are test kits available to do this, but its usually pretty obvious.

The base gasket absolutely does seal coolant passages from the crankcase. While possible it is very unlikely that this is the cause, as the crankcase alternates from pressure to vacuum, and you are not loosing coolant.

I would have the dealer do a leakdown test if the bike is being serviced anyway. This will tell you

[Jakobi]

Good thinking mate! With any luck they'll have a leak down tester or at minimum a compression tester.

It very well could be a bit of grease/oil from assembly.. It's just a little bit that floats on top and leaves a smear at the top level of the resevoir.

How much turbulance is normal? The water jumps up and towards the top of teh cap blipping the throttle with the cap off. It doesn't spit out the overflow though just bubbles up into the resevoir. Normal maybe? As stated definately doesn't use coolant and is running really strong and punchy. I had a few o-shit moments last ride when she'd hook up out of corners

I've got o-rings on order. I've got the bike going in tomorrow. They'll drain the coolant to change out the kick starter, and probably the oil aswell $$ cha ching.. so I'll know for sure if something looks really wrong. Combo with leakdown/compression I should know if somethings off.

Flush the system ride some more and hopefully the oil is gone, if not I'll pull the head. What kind of poor performance would you expect from a bike thats sneaking fuel into the coolant?