Join Date: Apr 2008
Location: The Northwet, U.S.
mysterious one-time coolant loss
Hmm. My stone-axe reliable '08 Wee with 45k miles had an odd issue on a recent trip.
I rode from Seattle to Pocatello, ID, which is about 750 miles. Temp was in the mid-90s for most of the trip; definitely not as hot as my previous trip to Boise a few weeks ago.
I parked it for a few days while vacationing. During return trip prep, I noticed coolant was a bit lower than usual, so I topped it off with Prestone 50/50 and thought nothing of it, then headed to Boise, which is about 250 miles from Pocatello. I stayed in Boise that night. In the morning, I found the coolant recovery tank bone-dry.
I immediately checked everywhere I could for evidence of a leak, and found none: no streaking or clean spots in the dust at or under any of the hose connections, pressurized or not, as far as I could see. I opened the radiator cap and saw that the radiator looked full and the cap and seal appeared undamaged and unremarkable. I didn't drain the oil, but what I could see in the sight glass didn't look abnormal in color or quantity. The overall temp on that section of the trip had been easily the lowest of the last 1200 miles; probably lower 90s or upper 80s and mostly overcast. The fan works; I've heard it at stop lights. The engine temp has never exceeded the usual 3 bars, and the engine runs just fine.
I bought another gallon of Prestone 50/50 (having left the other one in Pocatello, natch) and filled the recovery tank to a smidge over the full line, strapped the bottle to my seat just in case, and continued my trip. I checked it at each stop, and after dropping back to the hot-full line, it stayed where it was supposed to. After reaching Seattle and parking the bike overnight, I checked again cold, and it's at the low mark, which has been normal for the last 44k miles.
Soooo, I searched the forum and found some similar, but not identical, problem reports. The one-time loss of a large amount of coolant seems unusual. With the fairing off, I found that many of the hose clamps were looser than I'd expect, and tightened them a bit. Replacing the radiator cap and thermostat might not be a bad idea.
I will submit an oil sample to rule out an internal leak (and will watch for the obvious signs of contamination when I drain it), but I'd expect it to be constant if it were a head gasket, cracked case, or other internal failure.
Recent maintenance: About 4000 miles ago, I had the valves checked, so the case was opened then (none needed adjustment). 3000 miles ago, I replaced the spark plugs (the old ones looked good) and changed the oil.
Is there anything I've failed to consider? This is bizarre.
Last edited by dtalk; 08-23-2013 at 05:24 PM.