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Discussion Starter · #1 · (Edited)
Got back from a short ride and wanted to tinker with my fuel tables, trim and such on the PCV.

Everything was fine on the ride.

I had it running for about 5 minutes in the garage when the temp light came on.

I looked and the radiator fan was not running.

I shut it down and coolant came bubbling out of my overflow line and continued to do so, in a continually decreasing volume for over a minute.

I manually tested the fan by running a hot line straight to the contact and the fan worked.

One potential issue checked off the list, several more to go.

I did want some suggestions from anyone who has seen this issue.

With my one-piece radiator surround, I need to remove the forks to remove it, so I would like to have a full list of things to be testing for when I get in there.
 

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rad temp sending unit or"fan switch", check on stove with hot water, check conductivity
 

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Discussion Starter · #4 ·
Thanks.

That is already my prime suspect.

That would explain the fan not coming on, but the overflow bubbling over, Hmmm.

That may just be normal when it overheats, but I would love to get some input on that as well.
 

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My bike did this a couple summers ago. The temp light came on while stuck in traffic one day. I got it home and filled the coolant. Then let it run in the driveway for a few minutes. The fan never came on, the temp light came on, and all the coolant I put in came spewing out. Tore the bike down and found that the fan had somehow cut through its own power wire. I just crimped them together and tucked them behind the coolant tank. Haven't had a problem since. Just a suggestion of something to look at.
 

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Discussion Starter · #6 ·
Thanks for the suggestion. I will definitely be checking the wires while I am in there.:bigthumbsup:
 

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I would say it's the fan switch too, as long as the wires going to the fan are OK. There's a procedure in the manual to test it, but you can always do it the old fashioned way as rudeboy suggested and stick it in a pan of boiling water and see if the resistance changes. It's just an on/off temp switch.

I'd say the coolant boiling out isn't a symptom of another problem, just the result of it getting hot. Even though the reservoir looks kind of large it really doesn't have that much capacity. If it got hot enough to boil over I can see it easily filling the reservoir and causing it to overflow.
 

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Also if you haven't changed the coolant yet it may be sludge built up and restricting the flow. Distant1 changed a cts and flushed and filled. He told me it was pretty crappy in there. I will be flushing mine this winter/fall.
 

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Discussion Starter · #9 ·
Well, I tracked and tested the electronics from the CPU, to the relay, to the fan and all is well there.

I had flushed the radiator with my winter mods, but I figured it would not hurt to check that out. So, I flushed it, ran it and flushed it again. It was as clean as the day I put it in on the first flush. The second one was more a part of draining it to pull the thermostat.

Tested the thermostat. It indicates 88c, which works out to about 191f. It opened right at 190f.

So, I put it back together and ran a running test again bc I wanted to take oil temp and water temp.

Light came on, coolant started bubbling out so I shut it down and took my oil and water temps.

To my surprise, both tested at 188f

So, to me this says that I am not even at my thermostat temp yet, which means coolant is not flowing past the sensor that turns on the fan.

Further, I am well below the boiling point of the coolant.

I did say it was bubbling out, but never really seamed that hot. The bike never seemed hot. I would have never thought anything was wrong if the light had not come on.

WTF!

Well, I called it a night and I will hit it with fresh eyes tomorrow.

Any more thoughts are appreciated.
 

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Pressure test the coolant radiator cap. Maybe it is letting the coolant out to early. Also look at the water pump impeller. I know I have seen that problem in some cars over the years. How long is it taking to over heat?
 

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Discussion Starter · #11 ·
It took 5 minutes just back from a ride and 10 or so starting cold.
 

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There is an ECT switch that is screwed into the back of the thermostat housing---visible from the right side with green connector attached to it. That is what Dan (distant1) and I came up with on his bike. If you were to look at the schematics, it is what controls power to the fan relay and and fan. He was able to get one quick from Huff--but no dealer could get it for him quick. It is starting to effect just a couple of bikes, but believe it to be just a few bad sensors. Replace that ECT and it should solve your problem. You are having the exact same problem as Dan was.
 

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Discussion Starter · #13 ·
I had pulled the ECT and ran the tests on it.

It checked out fine.

Talked to local dealer service and they said if the light comes on, it is not the ECT as that is where the CPU gets the information to turn the light on.

I spoke with Dan and I do not believe his light ever came on, just coolant boiling over.

Spoke with FuturR tonight to brainstorm a little. He suggested maybe there was an internal short in the ECT that would have the signal from the CPU grounding out rather than returning through the resistor in the ECT.

Made sense, so I tested both prongs on the ECT for continuity to another ground and for ability to ground a hot lead.

Neither. The prongs are not grounded and there is no continuity to anything other than each other.

People keep suggesting to just replace the ECT and see if that works. I just hate to take stabs in the dark at a problem.

However, I am almost at that point with this issue.

I will post a WTB and call my dealer in the morning.
 

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I have had this happen on a different bike and it was the area where the cap seals that was pitted and once under pressure the coolant leaked into the overflow bottle then out of it's overflow onto the ground. these pieces are made out of some sort of plastic and not metal. :bigthumbsup:
 

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Discussion Starter · #15 ·
I have had this happen on a different bike and it was the area where the cap seals that was pitted and once under pressure the coolant leaked into the overflow bottle then out of it's overflow onto the ground. these pieces are made out of some sort of plastic and not metal. :bigthumbsup:
How would that make the fan not come on?
 

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Discussion Starter · #17 ·
Lack of coolant. Liquid transfers heat much better then air.
If it was getting hot enough to boil over, even under no pressure, the fan should have already been on.

Right?
 

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if i read correctly you said you were experiencing the overheating like symptoms at a tempature not even high enough to open the thermostat??

where is the fan switch located? engine or radiator side of the therm? and what temp is designed to turn the fan on??
 

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Discussion Starter · #19 ·
Now get this poo.

In trying to locate my problem, I have had the entire cooling system appart, tested every piece and found each on their own to be working.

So it was blowing my mind that I had this problem.

So, I took the whole system apart again tonight, disconected the battery, cleaned every connector and tested continuity on both sides of every connection.

EVERYTHING tested good.

Started the bike with a thermometer in the oil to watch temp points.

And what do you know, just like the manual says, at 160, the fan came on for 5 seconds, at 220 the fan came on and when it dropped to 210 fan went back off. Well within the specs from the manual.

On shut-down nothing bubbled off.

I am happy it is back to good, but a little miffed that it seems to have just been a bad connection somewhere in one of the lines. Maybe the CPU just needed to be reset and unpluggiing the battery was the answer here.


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I was going to have you call me, but I am glad to read that you have it all fixed up. :bigthumbsup:
 
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