Radiator fan running constantly

[sebjones92]

Anyone suggest any obvious problems with having a radiator fan running permanently on a vtr1000 motor? It's installed in a buggy, so has an oversized rad and fan (about 40cm x 40cm) or 16"x16"! I'm having trouble getting it to turn on, have tried bypassing sensors to close the circuit and see where the fault is but can't seem to solve it, instead of tracing back every cable to see where the fault is I figure I can simply hook it straight into the ignition system so it is running constantly. To me it's better safe than sorry? Just checking there's no harm in the engine 'not reaching running temp' and doing some damage? Engine gets driven pretty hard as you can imagine being on a buggy, not ever 'sitting at 100' for hours on a motorway.

Cheers

[KermitLeFrog]

If it has a working thermostat I can't see any problems.

[Stratman]

The engine is supposed to run between certain temperatures, that's why a fan and thermostat are fitted. If you are ragging a too cold engine - do YOU think that's a good idea? I wouldn't rely on someone telling me that it didn't matter but would take a morning to check the wiring and that the fans do come on when a certain temperature is reached. On my bike, the fans hardly ever cut in.

[sirch345]

I'm guessing you're not running a temperature gauge, one of those would be a good start. You could then see what is happening.

Changing the total volume of the coolant capacity, as in a bigger rad and may be longer hoses would mean the coolant taking longer than normal to reach normal working temperature. You could just need a new thermostat.

A Stratman says, you want the engine running at the correct normal working temperature, otherwise excess wear will take place,

Chris.

[alanfjones1411]

I would check the thermostat out in pot of boiling water to see if it would open

[KermitLeFrog]

Have you guys read the OP?

[Cadbury64]

That's a fine point Kermit!

If the thermostat is working then the engine will stay at a good running temperature with the fan constantly on.

The radiator fan power feed should be live whenever the ignition is on, the temperature switch on the radiator simply completes the ground side of the circuit. If the fan is constantly on then you should only need to trace the wiring from the motor to the switch, as there would be a short to ground there somewhere, unless the switch itself is faulty.

[tony.mon]

If you're going to go manual switching, suggest you just fit a switch with a light indicator next to the temp display. Then you can manually turn it off when starting in cold temps, and flick it on again once up to temp.
But you can easily fit a length of hose anywhere on the post- thermostat side (return) with a sensor in, feeding the fan motor.

[sebjones92]

so on a standard vtr the temperature switch on the radiator itself is what completes the circuit for the fan motor? Or the thermostat? I have replaced the thermostat and no change, tried closing the circuit from the green sensor which connects to the thermostat (assuming its another temp sensor?)

every other time Ive driven the buggy before the engine change the fan is pretty much constantly running after 5mins or so and continues for a few mins after shutting down the engine, which is why I didn't think running it constantly would be a big issue.

Maybe i could hook up a live feed to the fan assembly and run it through the rad temp sensor instead of direct to the motor. I understand you saying it would be worth me tracing back the wiring on a bike, but the way this thing is wired up isn't that simply, really awkward and tight spaces, you need to remove half the gear to get to any of the wiring.

[sebjones92]

which of the two sensors on the thermostat feed the dash temperature gauge? The green connection or the small probe below? As far as I can tell they are both temp sensors?

cheers

[Cadbury64]

The green unit connects to the ECM and I assume drives some change in ignition timing. The unit below this is the thermo unit which connects to the temp gauge, should be a green/blue cable connected to this.

The fan on the VTR is switched on around 100C by a temperature switch mounted in the LHS radiator. The switch completes the circuit to ground through the radiator itself. If you are using a different radiator then presumably you no longer have this switch. The thermostat plays no part in the fan operation and is a purely mechanical device that when cold restricts fluid flow to the pump/engine block, and when warm (80C or so) allows coolant to flow to the radiator(s).

[sebjones92]

That's everything I needed to know Cadbury, for now!

Thank you