The thread title says it all really, on idle and when driving the engine fan seems to spin up extremely fast and the car sounds like a jet engine. After listening to Tom's car on idle I'm beginning to think maybe I have a problem here.

 

I took a quick video of it after the car had been idling for a few minutes which I'll upload to YouTube shortly.

 

Just wondering if any of you have seen this before?

 

Thanks

Do you have an electric fan instead of the viscous one?

Viscous afaik, here's a video

Viscous coupling locked? Can you spin it freely with the engine switched off?

Spins with the engine off, can feel some resistance in it though not like a fan should feel.

Spins with the engine off, can feel some resistance in it though not like a fan should feel.

It should have some resistance, feels like its spinning in syrup, but should be easy to move.

Spinning in syrup is a pretty good way to describe it yeah.

These fans are belt driven right? So I'm super confused why it's spinning so quick while idling just below 1k rpm.

They will always be spinning to some degree, just depends on temperature conditions.

When cold, they will revolve, but only due to light internal drag, (can be stopped by a heavily gloved hand, be careful mind) when hot however, after the thermally controlled internal valve opens and releases a silicone oil it's a totally different animal.

The fan will fully engage and draw air at a noticeably stronger rate, (very audible) please do not try and stop it under these conditions.

A viscous coupled fan will operate when cold at first start up. Once the fluid inside the coupling has moved it should start to operate

normally and spin down (and get quieter) about a minute or so after a cold start on idle.

 

The coupling works as follows:

 

Based on a bimetal sensor located at the front of the viscous fan the sensor expands or contracts, depending on the air

temperature flowing through the radiator.

 

At Cold Temperatures the bimetal sensor contracts closing the valve, so the silicone fluid remains in the reservoir chamber.

At this stage, the viscous fan coupling is disengaged and turns at around 20% of the rotation speed of the engine.

 

 

At operating Temperatures the bimetal sensor expands, rotating the valve and allowing the silicone fluid to move through

the entire chamber to the outer edges. This generates enough torque to drive the cooling fan blades at engine operating

speeds and remain at a consistent temperature. At this stage, the viscous fan coupling is engaged and turns at around

80% of the rotation speed of the engine.

 

 

Source: BG Automotive

Edited December 22, 20177 yr by AndrewG

That’s a solid answer there Andrew. You even included the source, well done for taking the time over that.

That's awesome thank you so much for the information. When I was testing the fan yesterday spinning by hand it was on a warm engine, I'll go out on lunch and check to see how it's moving with a cold engine. If there is no movement at all I think it might be time for a new fan clutch.

That’s a solid answer there Andrew. You even included the source, well done for taking the time over that.

 

Agreed

Andrew is the most informative and helpful member in the club.IMHO

The information is always presented in a calm and logical manner without bias and without any alternative agenda.

Where would be the best place to buy a new one?

Where would be the best place to buy a new one?

 

The part number for a TT is 21082-40P10. A very expensive part in the UK (also try Mike@MJP):

 

http://www.allcarpartsfast.co.uk/nissan/nissan-2108240p10-coupling-assy-f/

 

The cheapest (I think) from the U.S. is Z1:

 

https://www.z1motorsports.com/water-pump-fan-and-thermostat/nissan/300zx-fan-clutch-oem-p-1709.html

Thanks Andrew

Thanks for the links, massive difference in price there ha.

Will buy one in January and this will hopefully solve it.

I probably have a used one for £20 if any good?

I probably have a used one for £20 if any good?

 

If it's TT spec then yes please mate that would be much appreciated.

If it's TT spec then yes please mate that would be much appreciated.

They are the same. I'll message you in a week's time when I get my hands on it.

That’s a solid answer there Andrew. You even included the source, well done for taking the time over that.

 

Yup - ditto.... Great explanation Andrew; thank you for that....:thumbup:

They are the same. I'll message you in a week's time when I get my hands on it.

 

No they're not Ali....!

 

NA and TT couplings are slightly different mate. I'm not sure how internally, but the TT version has a little yellow dot on it, to differentiate it from the NA version...:wink:

No they're not Ali....!

 

NA and TT couplings are slightly different mate. I'm not sure how internally, but the TT version has a little yellow dot on it, to differentiate it from the NA version...:wink:

Anyone confirm how so? Activate at a different temperature? because they will 'bolt in' both.

Anyone confirm how so? Activate at a different temperature? because they will 'bolt in' both.

 

NA version.....

 

https://conceptzperformance.com/nissan-infiniti-nissan-oem-21082-40p00-radiator-cooling-fan-clutch-non-turbo-na-nissan-300zx-90-96-z32_p_5810.php

 

TT version.....

 

https://conceptzperformance.com/nissan-infiniti-nissan-oem-21082-40p10-radiator-fan-clutch-twin-turbo-tt-nissan-300zx-90-96-z32_p_957.php

 

Apart from US$5 and a yellow dot, I don't know mate..... Maybe Andrew, Jeff or Jimmer will know...!

Quick research: NA spins the fan less at 50-60%. TT is heavy duty for 80-90% speed of engine. They also have different fan blade angles. Good to know.

I feel like I'm an expert on the viscous fan just from this thread ?

Thanks for the info guys.

Is your spare TT or NA?

I feel like I'm an expert on the viscous fan just from this thread [emoji23]

Thanks for the info guys.

Is your spare TT or NA?

It's an NA mate