CBF 1000 - Cooling system issue / warning light - ideas?

[NJD]

So before you continue to read its worth knowing that (a) I am taking the bike to the local shop tomorrow for them to have a look, but since (b) the shop I've sold the bike to on a P/X are now coming to collect it tomorrow afternoon there's a high chance the local shop will just say "we wont have the time, let them deal with it." So, in short, I'm asking here for ideas so I can give the guy that arrives as much information about what it may be as possible. Mainly because they've spent £140 on a new fuel tank alone for the bike I've purchased, on top of whatever other work they've done (yes their aware of problem).

Before Friday: no issues, no signs.

Friday 30 degree's: loads of town work, warning red light on dash comes on while waiting at a set of lights. Goes out when I move away. Comes on a couple more times on the way to where I'm going.

No light on the way home. Mostly on the move with minimal stopping.

Monday 30 degree's: light comes on once at the end of the ride at my destination. No light on the way home.

Today 21 degrees and cooler: light comes on once while waiting at a set of lights.

Narrowed it down tonight to fan kicking in after about five miles and then being in constant use until I finish my ride. Engine running warm, but not sure if warmer than should be.

- No signs of leaks.
- No instant coolant dump the first time the light came on, or otherwise.
- Water coolant pipes are warm after a ride.
- Fan works, turn on and turns off when the ignition is turned off.
- Changing the fuse did nothing (as expected, really).
- Radiator could benefit from a blow of compressed air (dirt).
- Bike starts and rides as should.
- Light only comes on after a few miles of riding in traffic when waiting at lights. Not on when ignition switched on. Goes out when on the move.
- Coolant fresh (few months old) and level appropriate (to best of knowledge).

The "red" light is a coolant temperature indicator. Owners manual says glows red when coolant is over specified temperature. Turn engine off and take to shop etc.

Thanks for any help.
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The do it all, T̶h̶e̶ ̶b̶r̶o̶k̶e̶n̶ ̶o̶n̶e̶,̶ ̶T̶h̶e̶ ̶b̶i̶g̶ ̶l̶u̶m̶p̶,̶ ̶C̶h̶o̶n̶g̶ ̶N̶o̶o̶d̶l̶e̶

[BigTim]

have recently sold my CBF1000 but the guys on www.cbf1000.com helped me out with various problems.
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MZ S50B, Suzuki GP100, Honda CBF1000, Honda Blackbird (I like my Blackbird)

[NJD]

[jaffa90]

It`s an age of lean burn engines due to emissions / pollution.
They all produce more heat when waiting / stopped at lights.
The time will come when all bikes have a stop and start system like modern cars.

[jeffyjeff]

NJD, Here are some suggestions:
1. Check the thermostat to make sure that it opens and closes through its operating range and that it is not broken or missing. Contrary to common belief, removing the thermostat will not cause the engine to run cooler. It will in fact cause the engine to be slower to warm up, but after it warms up the engine will run hotter, since a portion of coolant flow will be diverted away from the radiator.
2. Check the coolant hoses for bends or kinks that might restrict flow.
3. Check the radiator for obstructions to air flow; debris or bent fins.
4. Make sure the fan is working (you said yes), and that the fan has not been installed backwards. (probably not, but possible).
5. Inspect the water pump impeller. The impeller can cavitate if there is a restriction between the radiator and water pump.

You say the hoses get hot, that suggests a functioning water pump.
The fan operates, that suggests a functional temp sensor and fan circuit.
The fan "stays in constant use" for an extended period of time, that suggests the radiator is unable to reject enough heat to keep the coolant temperature within range.
I suspect a broken thermostat or obstruction to flow.
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History shows again and again how nature points out the folly of men - BOC

[colink98]

the only difference to cooling between being in motion and being stationary is the provision of air flow across the radiator.
When stationary this is the job of the fan.

if the issue only occurs when stationary.
then it must be an issue with the operation of the fan.
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PCX125 (stolen) - CBF600 (current)
Ride it like you stole it.
ride sensible and not like an idiot and you wont get 6 points in one week.

[weasley]

[xX-Alex-Xx]

[jeffyjeff]

[NJD]

Thank-you for all your responses. I took it down to my local shop this morning to have them read the fault codes and nothing came back, fan was kicking in at correct temp and something else they said. Surprisingly they didn't charge me, and I only phoned them yesterday. Result.

Passed on some of the responses to the guy that collected the bike, but even what I'd call the bikes worse parts he wasn't all that bothered about. I've told them, and done all I can, so nothing can come back on me at least.

Problem occurred Friday, and they wanted to collect today (phoning a day or two before). I only rode about three times since then, including Friday, so I didn't really have the time to properly rip into it. Either way they've got a workshop full of techs with more tools and equipment than I have.

I appreciate the help, but am glad its a problem I don't have to live with or resolve.
____________________
The do it all, T̶h̶e̶ ̶b̶r̶o̶k̶e̶n̶ ̶o̶n̶e̶,̶ ̶T̶h̶e̶ ̶b̶i̶g̶ ̶l̶u̶m̶p̶,̶ ̶C̶h̶o̶n̶g̶ ̶N̶o̶o̶d̶l̶e̶