Hi guys, thanks heap for the help
Sorry that it has taken me a while to get back to you – I have no internet in my house.
We had another 110F day and, again, the temperature gauge was brushing up against the red and would have passed into it if I’d been stuck in traffic any longer.
Are you sure you put the thermostat in the housing the right way? This is a common reason why it might not work.
did you bleed it properly when refilling it? after refill, start the engine with the cap off, watch all the bubbles come up and the fluid level drop. top it back up.
It sounds like you know what you are doing, but a few here have filled the systems from the overflow tank and not the radiator cap under the tank and had similar problems.
The system was properly filled (i.e. from the cap underneath the tank), the air fully bled/burped out, and the overflow tank topped to the required level. I also installed the thermostat facing the right direction.
Lol, you're basing all of this on that stupid temp guage? If your fan is coming on get over it and ride the thing.
I like to fix problems before they have a chance to cause more headaches.
Jack1313, can you give us more info on your 919? Miles and maintenance you've done outside of fluid changes.
A bit about the bike’s history: I picked up the 919 about six months ago from an older gentleman who had himself only owned the bike for about a year. It had 37 000 miles on the clock when I bought it and I’ve since put another 6 or 7 000 miles on it. It didn’t come with much in terms of service history, but the bike looked like it had been very well cared for, with some nice aftermarket bits (Power Commander, carbon fibre side covers and engine covers, a radiator guard since removed, exhaust system) that someone wouldn’t bother spending money on unless they cared about the bike.
I have performed the following maintenance:
Chained oil and filter
Replaced spark plugs
Replaced brake pads front and back
Changed the front and back tyre
Checked valve clearances. Three were slightly too tight (0.01mm) and another three were sitting on the limit – I re-shimmed all of them
I also replaced the radiator cap when it suddenly stopped holding the required pressure. It was at this point that I had a good inspection of the cooling system and discovered the missing thermostat and the brown coating on the inside of the engine. The water pump is good – there’s a little bit of rust on the impeller, but it is in good form and functioning fine.
There was some dirt clogging radiator fins. I’ve since spent some time scraping it out with a needle, which doesn’t seemed to have affected the problem. Overall, the exterior of the radiator appears to be in good condition.
IF the cap is holding. CHECK
IF the system is full and purged of air CHECK
IF the stat is opening NEW AND CHECKED
IF the fan is coming on CHECK
IF the temp is still rising
IF the water pump is moving liquid
Then there is a heat transfer problem.
Bent/blocked rad convolutions and/or coating on the inside of the cooling system.
I'm very suspicious of the coating described.
Oil heat can not be the cause, as the oil can't get that hot.
I think you and the others who mentioned it are on to something when you point the finger at this brown coating. The question is, what is it and is it inside my radiator as well as my engine? The stuff doesn’t seem to respond easily to system flushing products: when I used one, the water ran clean right from the get-go.
I’m going to strip the whole cooling system tomorrow, backflush the radiator, and take some photos to see if we can’t identify this brown stuff.
However, the heat wave seems to be over now, so I don’t expect to see the bike overheating again until we’re hit by another one.