[Headrush]

Hi all,
I've just ridden the bike to work. The battery was suffering from lack of use in the miserable weather we've had recently so I thought I'd give it a run as it's cold but dry here.
Anyhoo, I rode about 5 miles to get fuel before continuing on another 7 miles or so to work. Everything was fine before the fuel stop but afterwards I almost immediately got the red triangle and flashing temperature gauge. I've had this happen a few times before and just ignored it because I have checked the fan and found it works consistently when needed. Also, the warning seems to clear after a few minutes of further riding.
This time however, the warning didn't clear and it was still flashing away when I reached work and parked. The fan was running, I could hear it.

So, coming home last night, the temperature outside was between - 1 and 2 degrees C.
Rode all the way home without stopping and got no warnings at all.

I'm trying to understand which part of the system is playing up. It only seems to happen if I ride a short distance, stop (engine off), then resume the ride.

If it's a faulty sensor but the fan is coming on, then there's not really a worry of damage to the engine. If the thermostat is stuck closed then that might pressurise the system leading to leaks or head gasket issues. But there has been no leaking of coolant since the first time this happened several months ago and it appeared the header tank was overfilled. The coolant level has not changed since.

Just thinking that the fan should not run before the thermostat has opened. Don't know how that's controlled though.

Anyone got a similar experience or have a clue what's going on?
Cheers
Alan

 

[Richard230]

I have never had a problem like this on any of my motorcycles. But my guess would be a stuck thermostat.

 

[Headrush]

Thanks, I'm leaning in that direction myself. On closer inspection, the header tank had pushed some coolant out, I could see and taste it on the fairing. So, new thermostat ordered. Hopefully that will sort the issue.

 

[Headrush]

Well, I got the new thermostat and attempted to fit it yesterday. All went fine until I tried to drain the coolant. First off, the bolt in the block for draining just rounded out so that stayed put. Then I undid the bottom hose on the heat exchanger and at the first turn, the head off the bolt sheared off!
I carried on and replaced the thermostat, the old one was completely broken. The plastic cage holding the spring in place had failed so there was no way it could be operating. There was very little coolant in the system, just the heat exchanger.
Now the problem is getting the sheared bolt out. I've tried drilling it and using a bolt extractor but it's very difficult without removing the section and working on a bench.
I'm not sure how to remove the section where the pipes join, it appears to be one piece that holds the oil filter and the exchanger. I hope it's not part of the crankcase...
My main worry with this is that it involves undoing more bolts and risking more shearing.
Needless to say, I'm a bit demoralised at the moment. I'd take it to a proper mechanic but of course its already in bits so would have to be transported.

Any tips welcome.

 

[bmwroadsterca]

Please post photos of the bolts in question.

 

[Headrush]

Please post photos of the bolts in question.

I would have to wait until the sun comes up as it's 6.30am here.
But the bolt that sheared is a number 9 bolt that holds the pipe into the heat exchanger adapter shown in the image.
I'm hesitant about any more bolts shearing while removing the exchanger and adapter.