Ok so I decided to do a coolant flush on my 600f3 today so I purchased Prestone radiator flush and Prestone 50/50 coolant. I drained the old coolant buy pulling the big hose that connects to the water pump and collected the fluid in a drain pan. Then I reconnected the hose to the water pump. Now I slowly poured the entire bottle of radiator flush into the radiator, squeezing the hoses every once in a while, then topped it off with distilled water as it instructed on the bottle. Now I start the engine and let it run for around 10 mins. I was watching the temp gauge and waiting for the radiator fan to come on. The temp got almost all the way up to the top of the gauge but the fan never came on. At this point I got nervous about the heat and shut it off. As I was waiting around for the engine to cool so I could drain the radiator again, I noticed that the radiator overflow tank is full. I'm not really sure what happened but before I attempted the flush the fan would always come on as needed and I have never seen the overflow tank that full. I ended up running out of time so I pushed the bike back in the garage and plan to drain the radiator and overflow tomorrow but it seems like something is not right. Did I do something wrong? Should I just drain the radiator of the flush and distilled water then refill with the 50/50 radiator fluid and see what happens? I'm kind of at a lose here cause everything worked properly before hand but now something is not right? Any ideas?

 

Did you possibly knock or loosen any of the wires? You can test the fan system pretty easily. There's not much to it.

 

I don't really think that I bumped any wires but I am going to check the fan when I get off work today anyway. Do you think the fan not coming on would be a reason that the overflow tank got filled up? I only had the bike running for about 10 mins in the driveway and the tank filled up most of the way. But the bike did get pretty hot before I shut it off...

 

Yes. Basically the overflow tank acts as a reservoir when fluid gets too hot. Suction will pull it back into the radiator when it cools down.
The reason it's getting too hot is usually one of two things. 1. The thermostat isn't working or, 2. the fan isn't kicking on when it should. You could also have a blocked radiator but that's less likely.
If you had antifreeze in it before, it may been masking an existing issue that the straight water revealed.

 

Ok so I made sure that the fan worked by taking a flat head screwdriver, sticking it in the female flat connector of the fan and grounded it (with the ignition on of course) and it turned on so I knew the fan was not the issue. Next I removed the thermostat and noticed that it seemed stuck closed, so I cleaned it up a little then manually pushed it open a few times and reinstalled it. I did not check the thermo switch in the radiator because I had a good feeling that the thermostat was the issue and if the fan still didn't come on, I think the thermo switch was the only thing left that I hadn't already checked. Well lucky me, after refilling the radiator and burping the lines, I ran the bike for around ten minutes and the fan kicked on when it was supposed to. Thanks for the help hamlin!

 

Awesome news. Thanks for the update.