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peter_steer

Beta Evo fan problem

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Good evening all, I have a 2019 Beta Evo and i am having a problem with an intermittent fan. After about 5 minutes of running. the fan kicks in for a while then cuts out again, then it doesn't come on again and eventually coolant starts spitting out of the overflow . 

On a couple of occasions, i have noticed when i sit there revving the bike, the fan blade moves slightly a few times like its trying to start and then a couple of times it has eventually kicked into life, like the vibration from the enginGe has jogged it into working, but then it will stop again shortly and then eventually spit out coolant again.

The fan is working fine when i bridge the connector terminals, so its not the fan and i assume its nothing to do with the water pump, if that had failed then it may boil over but the fan should still kick in.

I think the switch is the main suspicion, just thought they either work or don't work, not sure that they work intermittently.

Any help appreciated. Thanks

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Your logic seems spot on. I would suspect the thermostat switch too, given all the things you have described. I suppose it could have a very dirty connection as one last thing to check before buying a new one.

 

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Fans, and electric motors in general, have a very high starting current. If jumping across the temp switch makes the fan run every time then I think you’ve identified a bad switch. If you have an ohm meter handy you could let the bike heat up and disconnect the switch and throw the ohm meter across the switch terminals. It wouldn’t take more than a few ohms of resistance to limit the starting current to the point the fan won’t start running but would keep running once started. I did take a Beta fan into the lab once to measure the running current and it was about 0.5 amp but if I limited the supply to anything under 10 amps the fan would not start. I think you’re up for a new switch. 

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Thanks for the replies, I think a new switch is what is required, just wanted some reassurance that was the case,I didn't want to just get one and find it was something else.

Cheers

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Hi Peter, 

From past experience i can say that it may not be the thermostat, because when you bridge the fan circuit connector which the thermostat plug is pushed into, you automatically move the wiring harness. There is another plug in that area which has two yellows in and two whites out, that is the power from the generator to the voltage regulator which eventually supplies the fan. The  cables may be run tightly near this plug and with washing etc the connection in the plug may not be good enough. With the fan connector linked try wiggling the wires and see if the fan stops and starts, but it does no harm to open and close these plugs to make sure that the contacts are clean and good and able to take current. Obviously if you link the fan connector and the fan runs constantly when you wiggle all the connectors, the thermostat is at fault.

 

Hope this helps!

 

2018 Wiring diagram.pdf

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HI Overdale,

Thanks for the reply, I ran the bike today and the fan came on after 4 minutes, then cycled on and off about 6 times over the next 10 - 15 minutes and then eventually the fan stopped coming in and it spat coolant out again.

I convinced myself that it is a dodgy switch and have now ordered a new one. I will have a look at those wires in the morning and see if anything changes. 

Thanks very much for that info.

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Thanks for that Overdale,

I checked the coolant level the other day and topped it up a little bit, i assume there was a bit missing from the blow out that i have been getting, this may have been happening for some time as I noticed a smell a few times but i only noticed the fan working recently as it is intermittent, I have now turned the overflow pipe around as advised by Lampkins, so it drips on the exhaust for early indication.

I checked those wires you suggested earlier today with the stat connector bridged, but despite a good wiggle it kept on running, and only stopped when i pulled the connector apart completely.

Hopefully the new switch will solve it, I will let you know.

Thanks for your help.

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Just a thought but if you keep filling it back up how much will it take each time? You might be putting more in than required and it’ll then spit out the excess. It should then not spit any more out. A few ml excess will be enough for it to push it out. Only fill with wheel up in air too. 

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Thanks Pindie and world trial champ, although I have only just learnt the bit about filling the coolant with the wheel in the air, I think the way the fan has been acting intermittently may indicate that all is not well with something. Yes the headlight has been removed when I got the bike 14 months ago and I taped up all the loose connectors and I have taken the tape off to check and they are all pristine. The new switch arrived today, so I will replace that tomorrow ( I could stretch it out for the next few weeks probably, no trials for a while ! ) and we will see what happens.

Thanks

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Just for the record, I fitted the new fan switch today and all seems fine. I ran it for about half an hour, turning it off half way through and the fan was kicking in and out nicely every 2-3 minutes, so hopefully it was a simple solution. Funny how you conjure up all sorts of possibilities in your mind while your waiting for parts to arrive !

Pretty straight forward job, apart from getting the old switch out of the radiator. I actually destroyed the old one, having to resort to putting a self tapping screw into it to pull it out ! it was certainly in there well, putting the new one in required a bit of rubber grease around the o ring and and a very firm push.

Thanks again to all those who helped,

 

 

 

 

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Yeah the more screwy the behavior usually the simpler the fix. Your intuition was correct all along.

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 By the way, if it does it again remove all the standard switches if you have not done it already. Like the headlight switch, tail light and all the extra wiring loom.

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