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super 400 · Posted: Fri Apr 03, 2009 3:27 pm Post subject: Radiator Fan

Just wondering i've never heard the fan come on, does anybody know how hot it has to be for it to turn on, just wondering if the thermal switch is still working.

admin · Posted: Sat Apr 04, 2009 11:01 am Post subject:

I've never heard mine come on either.
But I think my switch is dodgy, also my TEMP light doesnt come on when I turn the key, (could be blown light or indicate a fault).

Even in really hot weather, even stationary with the engine ticking over after a 100 mile ride. No fan cut in. - but they are very open engines, and have cooling fins too.

However because the cb400sf doesn't have a temp gauge, (the faired model might?) normally they have just a light, its a bit difficult to tell just how hot its getting.

TESTING THE FAN.
To check your fan is capable of working, just turn the ignition on and earth that wire on the rad temp switch to the chassis, the fan WILL work if its good.

Now its quite possible the temp sensor in the rad is faulty, its quite easy and cheap to make a manual switch to activate the fan, whilst still keeping the fan connected normally (so if the fan IS working properlly, it will work if it needs to)

HOW TO MAKE THE MANUAL OPERATION SWITCH.

The wire coming from the temp switch on the rad, splice into it, and connect a wire to the splice, put a switch on the new wire, then earth the wire to the chassis.
. By turning the switch ON, you are completing the circuit and this will operate the fan. When you think its getting too hot.
. But at the same time it only works with the ignition ON, so you wont discharge the battery, if some idiot turns it on.
. Also When the switch is set to OFF the fan will still operate as Honda intended

THE PROPER FIX.
After carrying out the test, and want to spend the money, you will need to drain the radiator, and then buy a switch from honda for £50-£60, fit this, and refill with coolant £10 ish. And if you get a dealer to do it, allow max 30 mins time to do the job (£50 an hour) = £25 labour.
_________________
Chris.
Honda CB400 super four.
Honda CBR900rr Fireblade.

super 400 · Posted: Wed Apr 22, 2009 1:26 pm Post subject:

cheers for the response, i checked to see if the fan works and it does, am starting to think it just doesn't get hot enough.

One other question i have is about an oil change, I have the new oil filter but am wondering how much oil i need i read somewhere that i requires something like 3.8 liters for a full change? also which oil would you recommend? thanks

solutions · Newbie Joined: 29 Mar 2009 Posts: 5

if ur changing just the oil it should be 2.7ltr and if you are changing oil with oil filter it is 2.9ltr