Tech Tip: check your overflow coolant tank

[Vdriveboater]

A few days ago I went for a 20 mile ride and suddenly I felt my right lower leg was wet and warm and realized it was hot coolant. The entire right side of the bike was covered with coolant and then a few minutes later steam started pouring out, partially fogging the windshield (at 50-55mph). I rode about 8 miles back to home and thank God nothing else happened, other than the oil level on the window dropped somewhat (couldn't find any oil leaks). The next day I removed the battery and tray and saw the culprit -- the right side curved coolant hose that goes into the block had split wide open. Prior to the ride I filled the coolant level to the top and installed a new 16psi cap that I bought from Fleabay (quality looks good). I thought for sure the cap didn't open up, creating too much pressure, because the original OEM cap had leaked when the engine got to full temp. The next day I did my due diligence and used my air compressor set around 20psi to blow in the hose at the neck overflow, but the air didn't get to the reservoir. I removed the hose from the reservoir and some coolant came out, and I could then easily blow it out with very little air pressure. What the heck? When I removed the reservoir and tried to pour coolant out of that bottom connector, nothing came out (aha). After shoving and twisting a small drill bit into the hole several times, a fair amount of "gunk" came out, and then the coolant would pour out (finally). So the lesson learned here, as part of regular coolant system maintenance, remove your coolant reservoir and clean out the bottom return line hole to insure that it doesn't obstruct coolant flow when the filler cap opens under pressure, and test it by re-installing the hose and reservoir and then blow through the hose that connects to the filler neck. I don't want anyone else to go through what I did. Fortunately the right hand hose that blew is still available new which is a stroke of luck.