well...my experience is that sensors usually don't malfunction like that, they usually work or they don't work.

it's possible that the switch has some gunk on it (mine did when i took it off) preventing it from reading actual temps and causing a delay. this could also be the case at the sensor end as well...making it read hotter than it actually is.

it's a toss up...i had the same issue, i switched everything...bike still runs a bit hot but prior to, the readings were bouncing up and down, indicative of air bubbles in the system or a boiling system.

 

Hmm... ok - had some jumping temps before, but its very stable now - think i got all the bubbles out. Could definitely be gunk, I'll try taking the switch out next coolant flush (in a couple days, want to get all that vinegar out). The sensor, not so good.. isn't it over by the thermostat somewhere?

 

yea it sits right below it to the brake side.
cooling issues suck...because you have to diagnose it one by one until you get it all.

 

Argh! Still having problems with my damn cooling system.

Now, it seems that the thermostat isn't opening until 205 F... Or at least that's what the reading on the dash says. And, the fan isn't coming on anymore at all - i let the bike idle for quite a while, and nothing. I did connect a wire from the fan switch connector to the engine block, and the fan came right on, so its most likely the fan switch on the radiator.

So, the symptoms: Bike stays around 205 F. on the freeway, higher around town. I let the bike warm up with the radiator cap off, and coolant doesn't seem to start flowing until 205 F., i.e. the thermostat doesn't open until then.

What I've tried to fix it:
- Flushed the system very thoroughly with a mix of distilled vinegar & water, as suggested. Then flushed thoroughly with distilled water
- Checked the thermostat (its 2 weeks old) with a boiling pot of water and a candy thermometer, seems to be within spec (opens somewhere around 185 F)
- Removed the fan switch and ECT (temp. sensor in the thermostat housing) and cleaned them both. Both had some gunk on them, but not excessive
- Filled system with a mix of distilled water and water wetter
- Let the bike idel for a long time, until the reading on the dash said 248 F!! I can't nec. trust the reading, but the bike did seam really hot, and when i turned it off, there was a lot of boiling over into the overflow tank that i could hear (which leads me to believe the bike was actually at a really high temp)

What is left to do? I can't figure this out for the life of me, and its the fourth time i've torn everything off so i could get to the thermostat assembly, I'm close to taking this thing in to a mechanic.... please help!

 

hey...run without the thermostat and see what the temp readings say, etc...actually this is probably the first thing you should've done. it'll take a long time to get up to temp, but once it does, everything should be running normal...if not then you know it's not the t-stat and then can search to see what the issue is...but as cooling system diagnosis goes, it's piece by piece mang! if you're up to it, you can take apart the water pump to see what's up with it, but make sure you get all the things you need as far as gaskets/o-rings for it.

if t-stat isn't opening until 205, either there's likely a bubble sitting there or it's not working. i know you just changed it right?

T

 

Any good tips on getting air out of the system? I let it warm up w/ the radiator cap off, and crank the throttle a few times, dunno if there's more i should be doing... thx!

 

just crank it with the radiator cap off and you'll see the coolant/water get sucked down, and it may do some girgling, etc...
also, helps to tap the lines here and there, and make sure it's on the sidestand so the cap area is the highest point in the cooling system.

sometimes, they are just stubborn!

T

 

thanks for the tips, i'll give it a try tonite. I've been doing most of what you suggested, but I haven't had it over on the sidestand, its been up on a stand. I'll try that out, should help.

 

I removed the thermostat, and rode the bike to work today. On the freeway, the temp stayed around 172 - not sure if that's good or bad, but at least it shows that the system can cool the bike enough (although i dunno if it should be able to cool even more). Also, the temps seemed to go up really quickly while on the city streets. I did about 3 minutes of street driving after getting off the freeway, and the temp went all the way up to 220 at one point, seems kinda quick to me...

Do you think its safe to say the thermostat is the source of my woes, or is there something else wrong here?

 

hey ruiz..

172 on the highway is very good...but let me know how it handles in traffic. the bike will get to 220 real quick in traffic, especially in the summer time.

your fan should turn on around 225 or very latest 228...and should bring it down to 220 or 222...see if it does that...
if it does then it's pretty normal. some do turn on faster, but shouldn't be any later than this.

don't put all your money on the t-stat just yet though. let me know what you find.

t