Beware of heat and a failed low-beam bulb

[Rockdoc]

I came across a bizarre design flaw^H^H^H^H foible on Katie while we were on the Continent that I thought I ought to share. On our way south from Santiago de Compostela in Spain to Guimaraes in Portugal we made a stop at the Portuguese city of Braga, which we'd been told was a nice place to visit. Indeed it was and we spent an enjoyable couple of hours exploring. When it was time to move on we found that the police had closed a lot of the roads, which diverted (or seemed to) all the traffic into just couple of streets with the inevitable result. I wasn't very bothered becaue the radiator fans have always controlled the engine temperature but this time it just kept climbing until I had the alarm signal showing on the dashboard. There was very little I could do because I was in the middle of three streams of traffic all going nowhere fast.

Luckily, things moved before the coolant boiled and the temperature came back down to normal levels. A check around the bike at Guimaraes only showed up a failed low-beam bulb. I couldn't imagine that tis was a factor but I changed it, obviously. It was the factor! Several other times we hit traffic and the fans kicked in as they should have done.

Now, tell me. What kind of so-called electrical engineer designs a circuit that combines a head-light bulb that doesn't give a warning of its failure with a critical feature like the radiator fans?

Keith

[woodey]

Ever think the two Problems were not related?

[JimH]

...Now, tell me. What kind of so-called electrical engineer designs a circuit that combines a head-light bulb that doesn't give a warning of its failure with a critical feature like the radiator fans?Nobody has designed such a circuit. If the headlight was in series with the fan the headlight would extinguish when the fan started. There is no other reason to link these systems together.

Coincidence does happen.

[ATFLT]

When my low beam went out I didn't notice the temperature gauge go up. Mine is a 99 but I doubt that the year matters.

[Ajlelectronics]

Now, tell me. What kind of so-called electrical engineer designs a circuit that combines a head-light bulb that doesn't give a warning of its failure with a critical feature like the radiator fans?

Keith

They don't. The two events were entirely unrelated. When in trafiic, the temperature WILL climb, the fans cutting in should deal with it. If it gets too hot, you are looking for something like a radiator matrix blocked with debris or perhaps a coolant loss.

[Rockdoc]

I don't blame anyone for being sceptical. I can't see any reason to link the circuits, either, but let me deal with the points raised as best I can.

This was not a case of the fans running but not being able to cool the system. The radiator cores are both clear. I don't know what's different in the States but I've never had a problem with a blocked radiator on any car or bike in 40 years of motoring in the UK and Europe.

I wasn't wearing ear-plugs so I know that the fans never started and my first suspicion was that a fuse had blown. There was precious little I could do about that on the road-side so I replaced the bulb - the obvious failure and any easy one to sort - and hoped that I could manage until I got home without the engine overheating again.

The coolant temperature rose above normal on several subsequent occasions but the fans always cut in and brought it down. It may well be a coincidence but, in case it isn't, I decided to share the experience. Believe or not as you please, my friends! ;)

Keith

[woodey]

Kieth I hope they are not related not just for your sake but for everyone who owns a BMW...because if you are right ...the enginering....I would not want to own a Machine that is put together by rubber bands and Duct Tape...I think that is a big reason why i purchased BMW...and willing to pay more for it is because is it built well, yes i know they have problems as all Motorcycles do ...but i believe These bikes are put together well and have been engineered great.

[Rockdoc]

I couldn't agree more, Dennis. The trouble is that it isn't an easy thing to check. I'm certainly not going to take the bulb out and deliberately try to overheat my engine! I hope that it is no more than a coincidence but I can't prove matters one way or another. On that basis I recorded things here so that it's in the public eye. It's a bit like reporting research findings in a technical journal. You can only report your findings and await the support or refutation of other people.

Keith