jhueym Posted May 14, 2012 Report Share Posted May 14, 2012 Hi I am having a bit of bother with the radiator fan not coming on, on my 2004 sherco 290. I replaced the otter switch and still no joy, then removed the connectors from the switch and joined the two together, the fan then came on so this confirmed that the fan will actually work and that there is power coming from the flywheel The bike has been taken out on long runs, 2+ hours and it still hasnt come on. The bike has plenty of power throughout the run but I did notice when climbing long steep hills that ther was some water coming out of the radiator overflow pipe, i thought this would probaly due to having too much coolant / expansion from being hot as it didnt seem to be boiling. The only thing I can think of is that the waterpump isn't circulating coolant through the engine properly and that is why the otter switch has not making contact. But I would have thought if this was the case,the bike would have over heated??? Has anybody else had this problem? Quote Link to comment Share on other sites More sharing options...
zerorev3rev4 Posted May 14, 2012 Report Share Posted May 14, 2012 (edited) Hi I am having a bit of bother with the radiator fan not coming on, on my 2004 sherco 290. I replaced the otter switch and still no joy, then removed the connectors from the switch and joined the two together, the fan then came on so this confirmed that the fan will actually work and that there is power coming from the flywheel The bike has been taken out on long runs, 2+ hours and it still hasnt come on. The bike has plenty of power throughout the run but I did notice when climbing long steep hills that ther was some water coming out of the radiator overflow pipe, i thought this would probaly due to having too much coolant / expansion from being hot as it didnt seem to be boiling. The only thing I can think of is that the waterpump isn't circulating coolant through the engine properly and that is why the otter switch has not making contact. But I would have thought if this was the case,the bike would have over heated??? Has anybody else had this problem? yes if coloant was not circulating properly it wouldnt of ran for long before seizing also i cant see how it maintained temprature for 2 hours use unless it was along a road and had plenty cool air drawn through ,, it definatly sounds like the thermo switch if the fan works when the 2 connectors are bridged ,, you can test the switch with a continuity tester if you place it in a pan of water and boil it up ,it should connect when near boiling if that works see if you can do the same test with the switch wired to the connectors boil it up in a kettle or on a camping stove (obviously be carefull a hand would be good ) you will need to extend the wires ,it could be possible to do this with a heat gun on the switch but be carefull not to burn the wires/connectors and you will need the bike running if this works then refit and fill system allowing any air to be removed then run the bike up it should work,, a lot of people tend to fit Gas Gas switches to shercos due to sherco ones been poor Edited May 14, 2012 by zerorev3rev4 Quote Link to comment Share on other sites More sharing options...
copemech Posted May 15, 2012 Report Share Posted May 15, 2012 That does seem rather unusual what you describe, as I would figure a bit more overheat symptoms. Thet will naturally push out a bit of fluid with expansion if the rad is topped off. You bacically need to cover the tops of the cores plus a bit which leaves room for expansion of the coolant. You can allways pull the three screws on the pump cover just to insure the impeller is turning if you cannot detect flow in the rad. Yet normally it is just a thermo switch at worst. You may test the switch as stated. When sitting running(no airflow stationary) the fan would normally come on in around 5 min or so depending upon the temps. Keep us posted! Quote Link to comment Share on other sites More sharing options...
jhueym Posted May 15, 2012 Author Report Share Posted May 15, 2012 I tested the switch which came off the bike originally by putting in a cup with a bit of hot water in it, that particual switch buzzed out so seemed to be working but I did not test the new one which is on the bike now. I will maybe try one of the gas gas ones as suggested. I pulled the hose off the left hand side of the radiator, started the bike for a few secs and some water spewed out, this confirmed that the pump is circulating but maybe not circulating well enough, I then thought that some of the blades could have come off the impellor in the pump so i removed the cover and they were fine, I kicked it over a few times and the impellor rotated. Is there anything else i am missing? This is my first liquid cooled bike so I am not that clued on that side of them. Not going to get a chance to work on the bike for a few weeks but will let you know what happens. I will get a few bits ordered for now. Thanks for your advice guys. Quote Link to comment Share on other sites More sharing options...
copemech Posted May 16, 2012 Report Share Posted May 16, 2012 I don't really think you are missing much, as things are fairly simple here. Only other thing I can think of may be an intermittant fan that is hard to start up. The motor does require DC voltage which means the rectifier must work properly so ck the earth point on it as well. Yet as you did state the fan worked when thermo switch jumped and you have had no real over heat symptoms such as pinking, I still wonder? Quote Link to comment Share on other sites More sharing options...
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