Faulty thermo fan not starting

[johnnyYTED]

  today riding back from Grey Gum my ST 's temp started to rise and when we got into Windsor and the slow traffic it got HOT, the thermofan didnt kick in..
can anyone suggest where I can start lQQking to find out why. I ask this for anything obvious  before I start pulling it apart, to possibly save time and $$$
thanx for any input in advance...

[Brock]

It may be the thermal switch has faile (top left rear of the radiator). test by removing the lead, and placing on a nearby earth, fan should then kick in. If still not work, it could be the relay (not sure where it is, or if there is one) or the fan itself.

How hot did the temp gauge indicate, needs to be at around 2/3 on the 1100

[alans1100]

The fan sensor is on the LH side of the radiator and the fan usually switches on when the gauge is about half of the normal range. You could have a faulty sensor or even a loose wire e.g.

Generally the fan shouldn't come on while your on the move as there should be ample air flow unless you're in stop/start traffic. Only advising on what mine does the for times I run into the city with pillion and towing trailer.

[ST2UP]

Put a by-pass toggle switch on my 1100 so I could bring the thermo in when stop in traffic etc.....worked well 

[johnnyYTED]

  thanx Brock for those hints,,   sitting at the lights it climbed to the top of the white,, thankfully they change and I got airflow agian and it dropped a little,for the last 5 yrs it has run about halfway along the white section...I stopped in on family until it cooled down and rode home when the temp was going down as the sun was setting and it stayed a little above halfway.. I had a good run home without any lights going red so I'm hoping nothing got tooo hot,
 ST2UP  a toggle sounds like a good idea  esp in Sydney traffic..
I'll spemd Sunday pulling of the plastics etc and check it out..

[saaz]

Also check that the radiator is full. When the overflow hose cracks at the neck of the radiator, the coolant level can drop enough so that the thermo switch does not know what the temperature is.  The overflow coolant tank might look too full in this case.  Just trim the hose and put back on.  Also, if the radiator cap has cracks in the sealing rubbers the radiator will not be pressurised enough, and overheating can result.  The thermostat may also be stuck shut.  These are the most common problems with the ST11 cooling system, mainly just due to age.

[johnnyYTED]

  today I tinkered with the fan,, followed advice and the fan works when I earth out the switch wire so I'm guessing its the switch itself. Will go for a ride and check if its getting hot stilll before I get a new one,, maybe the gremlins left and it will work...
 Thanx to all for the replies...   

[Brock]

We know stuff we does

[johnnyYTED]

   Thanx ppl , I now have a fan override on police switch #4 so I can turn the thermofan on whenever..
 I also found the owerflow hose had a crack so I fixed that also...thnx saaz     lQQks like a good excuse to go for a ride and test out the temp...hopefully my STeed wont get

[alchemist]

  Thanx ppl , I now have a fan override on police switch #4 so I can turn the thermofan on whenever..
 I also found the owerflow hose had a crack so I fixed that also...thnx saaz     lQQks like a good excuse to go for a ride and test out the temp...hopefully my STeed wont get

Hi Johnny,

Any chance you can please advise on how to tap into switch #4 to run onto your thermo? Looking at doing this myself.  Where did you have to pick up the wire from?

Thanks

[johnnyYTED]

Hi Johnny,

Any chance you can please advise on how to tap into switch #4 to run onto your thermo? Looking at doing this myself.  Where did you have to pick up the wire from?

[/quote]
 
 I got in in the tail ends.tomorrow I'll take some pics and see which pin# x2 took 1  to the Thermo temp switch and soldered it in, switch 4 when pushed in presto it worked.... with igntion.  a friend used a lecky cheka thingy to find the r = to #4 right ones I'll take pics 2moro and post them. And check my discription,,, memory 4gets sumfings...

[alchemist]

Thanks Johnny, all good... I just had a play around and found the orange and blue/black wires at the back, earthed one side and ran the opposite wire back to the thermo female plug on the radiator, all manual switched now.  Not the greatest at auto leccy stuff but stoked I managed working this one out with Brock's diagram.  Switch 4 is the one I tapped into.

[johnnyYTED]

 Dave glad u got it sorted.

here are pics of the police wiring in tail ST1100   I connected green9pin>>pin#7 wire to frame and pin#2 soldered  into thermostat switch wire.. It turns the fan on when the pol switch#4  is pushed in.Hope it helps..

wire colour shown in pics.


  credit to Brock for the wiring diag...