Ran hot today

[lather]

200,000 plus miles in 3 C14 and never a hint of over heating. Today my 08 with 110,000 mile ran hot in city traffic on a cool day (65F) I was doing some Christmas shopping in and looking for a BBQ joint for a lunch break and noticed two bars above normal line. I headed for the Interstate,  got a brief overheating warning on the dash but it only lasted a second as I was maintaining good pace now. Once on the Interstate after 3 miles or so of 75mph it was back to normal  on the gauge and staid that way the 40 miles home.

Once home I let the engine idle and soon had the two bars over the line and no fans on. Remembering my 99 VFR800  overheating problems I started looking in the manual for where the water temp sensor was located. On the VFR it was plugged directly into the radiator and just a simple on off switch to control the fans. Not on the C!4. The temp sensor is plugged into the rear of the cylinder head, requiring throttle body removal for servicing!

Fortunately the problem turned out to be a blown fan fuse. So now I am wondering what would cause the fan fuse to blow. I checked both fan blades and they spin freely.

[maxtog]

Fortunately the problem turned out to be a blown fan fuse. So now I am wondering what would cause the fan fuse to blow. I checked both fan blades and they spin freely.

It might have been temporarily hung with a rock or twig or something that then later fell out while riding.

[Boomer]

It's rare these days but fuses can also fail due to vibration rather than over-current.
If the fuse goes again, then you have a problem, but until then I wouldn't worry about it.

[lather]

Thanks for the comments. There has been a lot of tree debris on the country roads I travel. And the fuse was different from most blown fuses I have seen, usually just a clean gap. This one has a black burn mark and no gap that I can see with the naked eye. I had to test it with my multimeter to know it was blown.

[Boomer]

Thanks for the comments. There has been a lot of tree debris on the country roads I travel. And the fuse was different from most blown fuses I have seen, usually just a clean gap. This one has a black burn mark and no gap that I can see with the naked eye. I had to test it with my multimeter to know it was blown.

If the burn mark is off-center then it's almost certainly a vibration failure.
The fusible link will have vibrated loose from one of the legs of the fuse and it will have been arcing across the gap, causing the burn mark, until the gap became too big for it to arc across.

[lather]

It is off center.

[Boomer]

That looks more like a normal fuse blown to me, but could still be arcing damage.
Keep an eye on the fuse, and if it blows again, I would get the wiring and fans checked out.

[lather]

The fan fuse blew again today. I swapped out the relay box with one from my parts bike. Going to try to check the suspect relay with my multimeter per page 16-107 of manual.

[lather]

Swapping relay boxes didn't help. I'm going to pull the plastic and test the fans, I assume one of them must be bad. Waiting on an air filter since I might as well change it while the plastic is off.

[maxtog]

Swapping relay boxes didn't help. I'm going to pull the plastic and test the fans, I assume one of them must be bad. Waiting on an air filter since I might as well change it while the plastic is off.

That is what I was thinking.  Spin them by hand, maybe a bearing is slightly failing and dragging (or something else in there causing drag) and causing the fan to pull too much current?

[lather]

I'm stumped. I pulled the radiator off and tested both fans with a 10 amp fused 12 volt connection. Both fans run fine, no unusual noise. I let them run a minute or so, they didn't feel hot.
Any ideas?

[tweeter55]

Let them run 5 to 10 minutes and then feel if they get warm or not. If there are bad bushings or bearings they probably won’t show up immediately.
Also, were you able to check the amperage draw on each one and then recheck them after they have run for that 5 to 10 minute period of time.
My $.02 worth.

[lather]

Let them run 5 to 10 minutes and then feel if they get warm or not. If there are bad bushings or bearings they probably won’t show up immediately.
Also, were you able to check the amperage draw on each one and then recheck them after they have run for that 5 to 10 minute period of time.
My $.02 worth.

Thanks for the suggestions. I only ran them for about 2 minutes each. I will run them longer. But I think this type of testing will not be very valid due to the large  temperature difference testing off the bike. I think I recall from high school science that resistance goes up with the temperature. Also I probably have to rig a connection to run both fans at once.

I did not test amperage, not sure how to test that.

OK, found an inductive amp meter in my shop. I've got the two two fans hooked up in series and will test when the weather gets warmer in a couple days.

[lather]

UPDATE
I hooked up the two fans to run together off a 12 volt batter (the one in my R3) I ran them for about 12 minutes testing the amps with an inductive ammeter.
Initially the amperage was about .155, fluctuating constantly between .149 and .160. After 12 minutes the amperage had only dropped slightly: 1.35-150. 
The fans never acted up in any way, the sound never changed. So it appears to me the fans are ok and I am still without an answer to what causing the fuse to blow.

[Rubber_Snake]

At this point, I would inspect the wire harness for a possible grounding issue.  Something has to be causing that fuse to pop.  I know this could be a pita, but you could try rewiring (even if temporarily) from the fuse box to the fans and see if that stops the problem.  My 2 cents…

[lather]

At this point, I would inspect the wire harness for a possible grounding issue.  Something has to be causing that fuse to pop.  I know this could be a pita, but you could try rewiring (even if temporarily) from the fuse box to the fans and see if that stops the problem.  My 2 cents…

Thanks for the idea. Reminds me of My VFR that had a really poorly designed cooling system, (unlike the Concourse). It had two radiators facing sideways! The solution was to wire up a manual switch to overide the temperature sensor switch and turn on the fans whenever the meter showed anything over 190 F.

I have two good fans from my parts bike, going to install them and see what happens but if the fuse keeps blowing I may rig a manual control circuit and bypass the problem.

[lather]

Success! Swapped out the fans from my parts bike and reinstalled the radiator. Fans came on with two bars above normal.

[maxtog]

Success! Swapped out the fans from my parts bike and reinstalled the radiator. Fans came on with two bars above normal.

OK, so now we wait again