Legend - Loss Of Cooland

Just recently, my 2000yr Legend has started loosing coolant, especially after a fas blast. The coolant is being pushed out into the expansion tank - once its full it goes everywhere.

As an aside - I have not heard my radiator fan come on recently. So I shorted out the wires on the cooland switch (in the thermostat housing) and the fan burst into life - so the fan switch is suspect. I tested it with a ohm meter while suspended in boiling water - nothing - Open Circuit. So I replaced it and on my next ride out, after about 100miles and a fast blast home on the motorway, the red light came on AND the fan burst into life.

This proved:
a) A fast blast pushed coolant out
b) The red lamp sensor is working
c) The fan sensor is now working as well

Out of interest, I suspended my new fan switch in boiling water expecting to see the resistance change - but I got the same result as with the original switch - open circuit. Could it have failed already? Or, what am I doing wrong? I'm using a cheap digital multimer on 2000kohms range (it can read my skin resistance on this range). The book says it should read more than 1Mohm when cold, and less than 0.5ohm at 99deg.
I just get an open circuit on both the old and new units - and yet I heard the fan running on the new unit!!

Sitting here, very perplexed!

Andy S

 

Further developments today...
Old Fan Switch - I put a heat gun against it - & guess what? - it works!!
Trouble is, I have no idea what temperature it flipped at. Its stamped 100 deg - but it did not flip in boiling water (neither did the new one) - so the above test from the manual is useless - proves nothing - & made me buy a new switch into the bargain.
So, one thing has cahnged, the £1.74 'O' ring has been replaced.
Next - I took the thermostat housing apart & tested the thermostat - that worked fine, as it opens at around 88deg, well below boiling point. I changed to 'O' ring too (less critical).
Its a bu**er to close the thermostat housing, though - took two of us - one to compress the spring and the other to insert the bolts.
As the thermostat housing is made of plastic - I found the hose outlets distorted - maybe that was my problem - hoses not sealing properly.
So, with my trusty heat gun and a Jubilee clip, I made them round again.
Touch wood - today I tried a static test. With the fuel tank in place of the seat and a long fuel pipe connected, I ran her up to temperature, whilst holding the top radiator hose, which stayed cold initially. As the engine got hotter, so the top hose suddenly got hot as the thermostat opened - & the finally the fan came on without the red light coming on - & no water leaks anywhere.
Maybe it was just the Fan Switch 'O' ring that had got tired all along.?

Thanx for listening - I think we are OK now!