Hi,

As per the title, how far up the scale on an NC35 is normal before the cooling fan somes on please?

Thanks!

EDIT: In my case, a little over half-way then the fan starts. Thanks to all who contributed here and helped me close out the problem quickly and easily!

Usually about 120 if I'm not mistaken.

Since the thermoswitched and the temperature sender for the clocks can vary, where abouts the fan comes on may also vary.

It's very near the end of the scale though. if the fan isn't on when the needle is at the top of the scale it's not gonna so kill it just as the needle enters the red before you break engine ^_^

The cooling system is basic and easy enough to check, while a thermometer helps its not essential.

Cooling system specs:

Thermostat FULLY open @ 95°c (Min 8mm lift), starts to open @ 80°c - 84°c

Fan Switch:

Cooling fan cut-in temperature: 95-105°c (located on radiator)
Temp sender resistance: (located on thermostat housing)
@
60°c 94 -117ohms
118°c 16-19 ohms
122°c 14.4 - 17.3 ohms

A cooling system flush is wise on any old / neglected NCxx.

1. Flush rad(s) and block with pleanty of water, consider a chemical treatment if rust is present.
2. check for bent rad fins and straighten where appropriate and remove any dirt / gunge by soaking radiators.
3. check water pump, thermostat, cooling fan switch and temp sender are working. (generally they either do or don't, resistance values are just useful guide.
4. refil with fresh coolant and bleed for air.
5. done

viper_biker wrote:Usually about 120 if I'm not mistaken.

So where is 120 indicated on the scale please? There are no numbers marked?

Thanks.

NC35! wrote:

viper_biker wrote:Usually about 120 if I'm not mistaken.

So where is 120 indicated on the scale please? There are no numbers marked?

Thanks.

As I said they may vary a few degrees between your sender and dial but as a rule of thumb the fan will be on when the needle is at the top of the scale.. if it's not on by then something is wrong.

Have you replaced the temp sender or just re-connected it back up?

http://www.youtube.com/watch?v=LT990wyb2dA" onclick="window.open(this.href);return false;

Man what a road!

i was wondering this too, when i got the bike i put samco hoses on a new fan as the old didnt work, i also cleaned the rads up but i dont think iv ever heard it going, the temp alwasys stays arround the 90 area, iv never enen seen it pointing strait up, is this normal or is my cooling system just working very well?

Neosophist wrote:

NC35! wrote:

viper_biker wrote:Usually about 120 if I'm not mistaken.

So where is 120 indicated on the scale please? There are no numbers marked?

Thanks.

As I said they may vary a few degrees between your sender and dial but as a rule of thumb the fan will be on when the needle is at the top of the scale.. if it's not on by then something is wrong.

Have you replaced the temp sender or just re-connected it back up?

Hi,

When I was fiddling around earlier, the engine had gotten very hot to the point where the needle was between the white bar and the red bit - very close indeed to overheating. Thankfully I noticed before it went red, but it occurred to me the fan should have come on by now.

I pulled the connector off the fan switch thing which is screwed in to the lower radiator and shorted it to earth, the fan came on and spun away quite happily so I'm happy all the wiring and electrical parts are okay - I'm not so sure about the actual switch itself though. I guess I need to boil it up and test it out.

Thanks.

PS - Agree, nice road :D

Might want to check there is connectivity between earth and radiator.

There should be as the body of the fan is earthed and bolted to the rad but it is possible if there was some bodgery going on that it isn't. Very easy and quick to test in comparison to the fan switch!

Druid

fastdruid wrote:Might want to check there is connectivity between earth and radiator.

There should be as the body of the fan is earthed and bolted to the rad but it is possible if there was some bodgery going on that it isn't. Very easy and quick to test in comparison to the fan switch!

Druid

Basically, I need to check for continuity between battery neg and, for example, the bolthead which holds the radiator and fan together?

Thanks