Hi and merry christmas.
The fan comes on straight away ona cold start. Is this normal?
I've been having heater probs and wonder ifthis could be the cause or do all discos have a fan that's permanently on?

If the fan is 'not' supposed to be on all the time, what could be causing it to be always on and how do I remedy it?

 

Have you checked your coolant leavel, maybe too low to heat up the truck and also the temp sensor may not be able to read thye temp. Or the temp sender is failing or shorted.

 

Checked the coolant level which was ok and then bled any air out (there wasn't much) but noticed the fan comes on as soon as the engine starts and I was wondering if a previous owner could have bypassed the thermo (like they used to do in the old days with a hairpin). If so, how would it be undone?

Oh, another observation, the brass nut at the top of the radiator had no thread on bolt or hole, is this normal? It simply pushed in or pulled out.

I have a long journey from my area (Peak District) to Leicester and then from there to Conwy castle tomorrow night so hoping all will go well. My pal has let me borrow his 40ft yacht in Conwy marina which is at the foot of the beautiful Conwy castle so should have a cool new years eve throwing a party on his boat and watching the fireworks from the castle as long as the Disco runs cooly LOL.

 

Is your a/c on? The fans come on with the a/c immediately. Another thought is it might be a coolant temp switch. Again, not sure on diesels, but gas one's we have a coolant temp sending unit for the gauge and a switch for high heat that triggers the fans. Might be a bad connection or sensor.

 

It is perfectly normal for the clutch fan to come on when you first start the truck. All of the fluid settles to the bottom of the viscous clutch housing and until it is distrubuted by the fan turning it will be locked up. Just the nature of the beast.
It should only happen when it has set overnight or all day at work. If it is really hot out and you turn the truck off the heat build-up under the hood can lock the bi-metalic spring on the front of the fan too.

 

Tdi has a viscous fan - yes it will turn when the engine is first started. With the engine off and cold you should be able to spin the fan by hand. With the engine off and hot the fan should be locked tight by the viscous coupling. If the coupling is locked while the engine is cold then there's something wrong with the viscous unit and it'll need replacing.

 

I thought he meant the electric fans...

 

I thought he was talking about the heater fan in the cab.

 

I was referring to the radiator fan in this thread, however in another thread I was referring to my heater blowing hot and cold even though coolant is full.

A further development is after a 100 mile trip, it's running too hot. Not checked water level yet.

I'm sure all these things are related. Hope it's not the engine. Could it be?

 

I doubt it is the engine. I would replace the thermostat. It is cheap and a good place to start.