On a zed, am i correct in thinking there are two fans? An electric one and a viscous one?

Should/do either of them cut out above a certain RPM. My car has a dodgy sensor that needs looking at (o2 sensor im sure of it) but when holding it at revs the other day as it was climbing past 2800rpm I think it was fan noise dropped massivly as if one had stopped, letting the revs drop down the fan noise came back. Is that normal?

I am not 100% sure but i think you will find the second fan is for the air con rad , thats if you mean the one behind the rad

yes on a OEM car (IE not modded) there are indeed two fans, one is coupled to the engine direct (viscous one) and one attached too the radiator of the Aircon (electric one), you can test the electric one by unplugging the square connector on the front water pipe (not the smaller one which is your temperature sender going to the display on the dash) with the ignition on, it should pop into life. but yes you should notice that when the fan comes on, the engine revs slightly more due to it drawing more from the battery, even more noticeable engine rev with the A/C pump engaged.

Edited September 23, 201015 yr by vodkashots

That's not what I was meaning really. If I rev the car the fan is appears to run up to a certain revs but then passed 2800 rpm the noise from the fan Disappears. What I'm asking is does one of the fans stop after a certain engine speed is ?

i dont belive it does my understanding of the viscouse fan is it designed to pull air more than if it was just stuck to the block spinning at the same rpm of the engine. hence the clutch part of it. i think they spin faster than engine rpm at idle then slow off to engine rpm when it starts to rev but it shouldnt ever stop if the engine is running.

i dont belive it does my understanding of the viscouse fan is it designed to pull air more than if it was just stuck to the block spinning at the same rpm of the engine. hence the clutch part of it. i think they spin faster than engine rpm at idle then slow off to engine rpm when it starts to rev but it shouldnt ever stop if the engine is running.

 

how could it spin faster than engine rpm? the idea of a vicose fan is it works by the engine temperature the hotter the shaft from the water pump gets the tighter the clutch grips the shaft thus bringing the fan into use once it's cooled it down enough then the fan releases then runs either slower or not at all till temp rises so it is possible that at higher revs the fan has done it's cooling then backed off but if the temperature rose back up it would cut back in

Need a new viscose fan clutch, its worn out bud, so when it gets over a certain amount of revs its not gripping properly.

ah sorry i misunderstood. thought, there was a gearing to it. then the gearing disengaged or changed once it was upto a speed.

Its done by temperature and RPM it has a bi metallic strip in it but they wear out, could well be the problem when its cold see how easy it spins by hand. From memory a good one will only spin about quarter of a turn. My old one went round a good few times lol.

Ahh fair enough not a big issue then. Just a case of changing he viscous fan for. Better one? How big of a job is that?

Ahh fair enough not a big issue then. Just a case of changing he viscous fan for. Better one? How big of a job is that?

 

easy, but 4 bolts holding the fan on, remove the fan its self, the tackle the clutch. easy switch tbh

Its not a bad job bud!!

aww...I thought this thread was going to be about people that really like Engine bays

aww...I thought this thread was going to be about people that really like Engine bays

 

Me too. Thought there'd be loads of shiny engine bay pics to ogle!!

I've got one shiny engine bay!!!! LOOK!!!!!!SHINY!!!!