CBR600fm got a bit hot today

[jamiey]

Hi Everyone,
I took my 1991CBR600fm for a little mid winter run today as the sun was shining and i had a day off work - just perfect!!
I noticed when sat in traffic that the temp gauge had risen to almost on the red, luckily I was away riding again with plenty of getting into the radiator before the gauge got right upto the red.
When I got home I left it running on the drive for a while and the same thing, needle (slowly crept up towards hot) so turned it off before it overheated.

I'm new to the forum here so thought i'd try and seek some advice before going out wasting money on bits I don't need

what would be the first thing to rule out?? thermostat perhaps?? fan switch?? or just a simple new lot of coolant - anyone know any simple diagnostic tests to determine the cause, or even is getting to the top of the normal temp range usual with these bikes?? Its my first CBR so not too sure, its fine when i'm riding, no problems whatsoever and the temp is always normal, the problem is after about 5 minutes when stood still

Cheers

Jamie

[fatzx10r]

did your fan start working when it got hot?

[rainman]

Water pump?

Also worth checking if the fan comes on - if not your temp sensor (assuming this works on your bike like it does on mine) are probably stuffed. (Or maybe the fan, I suppose - unplug it and put 12V across and you'll soon tell).

When did you last change the coolant?

[CB ARGH]

I'd say check the coolant levels/condition... Also figure out wether or not the fan comes on once it starts getting hot. You could also check to see if the radiator is dirty which could prevent air from getting to the small bars, which in return would heat up the bars, which means hot fluid cooling the engine... not good! Degreaser does the trick with that

Otherwise it could always be the thermostat, these aren't so dear from what I know (used to work at Repco)... but motorcycle thermo's may be different.

Good luck mate

[jamiey]

Not sure when the coolant was last done, so i may start with that. The fan did not come on once it started getting hot

[Ragingrob]

Well if the fan did not come on once it started getting hot, then that could well be your problem. Run the fan from a 12V battery just to see if it works, then check that the wiring to the fan is intact and contacts are clean, if it's still not going when it gets hot then you will need to check the thermostat and just get another one.

[Max Preload]

Not sure when the coolant was last done, so i may start with that. The fan did not come on once it started getting hot

Don't start with that - old coolant in itself will not cause overheating unless there is corrosion caused by that and you cannot fix that by changing coolant. Start with manually powering the fan since it didn't come on. If the fan works, check power to the fan switch and the fuse. If there is power, check the fan switch operation. I think that is where you'll find the problem.

Once you've confirmed the fan is again correctly operational, THEN change the coolant.

[jamiey]

Don't start with that - old coolant in itself will not cause overheating unless there is corrosion caused by that and you cannot fix that by changing coolant. Start with manually powering the fan since it didn't come on. If the fan works, check power to the fan switch and the fuse. If there is power, check the fan switch operation. I think that is where you'll find the problem.

Once you've confirmed the fan is again correctly operational, THEN change the coolant.

Ok, the fan is definetley not coming on when hot, how would i go about manually starting the fan?? I can access the fan switch but haven't been able to take it out yet, connector looks ok...................

[rainman]

Ok, the fan is definetley not coming on when hot, how would i go about manually starting the fan?? I can access the fan switch but haven't been able to take it out yet, connector looks ok...................

Just trace back from the fan to the nearest connector, unplug that (don't lose the other end into the bodywork), connect 12V and see if it spins. If you don't have a spare battery just pull a pair of test leads direct from the battery. I'm assuming you have some suitable wire, and clamps or clips to keep it hooked up to the battery. Or a suitably gullible person to hold the wires on for you

Then, once you know whether it works or not, reconnect to the bit you didn't lose... and let us know what you find out.

[jamiey]

Just trace back from the fan to the nearest connector, unplug that (don't lose the other end into the bodywork), connect 12V and see if it spins. If you don't have a spare battery just pull a pair of test leads direct from the battery. I'm assuming you have some suitable wire, and clamps or clips to keep it hooked up to the battery. Or a suitably gullible person to hold the wires on for you

Then, once you know whether it works or not, reconnect to the bit you didn't lose... and let us know what you find out.

I have a 12v battery charger, will that work?? And just the poistive lead onto the wire coming from the fan right??

[rainman]

I have a 12v battery charger, will that work?? And just the poistive lead onto the wire coming from the fan right??

Not sure how the charger would like having a fan as a load. Be better to just get two wires from the battery (+ and -, the fan connection should have two wires in the connector.

Do you have any old two core flex from a lamp power cord or similar? That'd work.

[jamiey]

Not sure how the charger would like having a fan as a load. Be better to just get two wires from the battery (+ and -, the fan connection should have two wires in the connector.

Do you have any old two core flex from a lamp power cord or similar? That'd work.

Thanks for all your help on this one, its driving me mad. It appears that only 1 wire comes from the fan, it has a connector that links it to the fan switch - so if i fully take off the connector there will be 2 wires right for + and -

[rainman]

Thanks for all your help on this one, its driving me mad. It appears that only 1 wire comes from the fan, it has a connector that links it to the fan switch - so if i fully take off the connector there will be 2 wires right for + and -

No worries, I had a similar problem a while back, different bike though. Hang on while I check a parts catalogue for your bike to make sure I am not confusing the issue.

[rainman]

Hmmm. Lots of different models of CBR600, I see (sorry, I'm a sportsbike eejit). Closest I can find is this. Page down to get to the fiche image. Hope that's kinda what you have, the fan models change a bit based on year, it seems..

From the picture it kinda looks like the fan has a separate wire with an earth tag, so if your bike looks like the zoomin picture the game becomes how to connect a single wire from the + terminal of the battery to the other (non-earth) tag of the fan.

The only question I have is what that other bit is that's connected in the middle of the assembly. If it's another connector that has both + and - terminals it probably isn't a good idea to pick one and guess cos if you get it wrong you'd be shorting your battery.

Do you have the fan out of the bike, or is it still mounted?

[jamiey]

Ahh that helps a bit, looks like i'll have to get in behind the radiator, i'll have a go tomorrow and let you know how i get on, thanks for that, much appreciated