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"Richard is correct." Thank you 98lee, I don't get that often.
Regards,
Richard Flood
Commerce Township, MI
Richard is correct. Coolant coming out at the cap indicates that the OUTER cap gasket is not sealing.
In your middle picture, it shows a nick in the outer sealing surface of the filler neck between 10 and 11 o'clock. That would cause a leak of coolant along the threads as the bike heats up. It would also suck air into the radiator as it cools down. Do yourself a favor and follow Greg's suggestion and buy a new filler neck. It will probably solve all your coolant problems. The cap has to have a good seal at BOTH the inner and outer gaskets.
Make SURE that there are no cracks in the hose from the filler neck to the expansion tank!
So I had some time this morning and decided to squeeze hoses again. Nothing to lose, right? Put the bike on the side stand and continually squeezed the hose that runs across the top of the engine block. It still bubbled up air and some large ones that spit coolant out the top, and the coolant level, while visible, was down in the upper hose. I also squeezed the lower hose, but in using both hands I could not look into the filler neck. I went back and forth between the two. Guys, can these systems really be this difficult to remove trapped air? I took my time filling it.
I put the bike on the center stand and started it up. The coolant rose up in the filler neck to the point where I had to shut the bike off or it would have spilled over. This shouldn't happen. If I have understood the procedure for these bikes after replacing coolant, I should be able to run the bike with the cap off to watch for trapped air being released. As Paul mentioned, and it was a thought I had, this indicates trapped air being heated, expanding and raising the coolant level.
Tom
1. Obtain a good turkey baster syringe and a two quart pan.
2. Start bike.
3. As coolant rises in filler neck use baster to draw out coolant and squirt it into the pan.
4. When all of a sudden you get a big burp of air clean up the mess.
5. Slowly refill the system while the engine is running.
Lee,
All fair comment considering. As I upgraded the filler neck cap to the new style, which had new rubber seals obviously, then I have no choice but to replace the outer rubber seal or revert to the original cap altogether. There aren't ten different ways to hand tighten the cap.
I have been remiss by not updating this. When I installed my coolant temperature gauge last month with all the associated bits, I also installed a complete new rad cap. It seems to have solved the problem. I have put on several hundred miles since and there has been no sign of coolant escaping from underneath the cap.