Seized Fan Clutch

[TimW]

Hi Guys,

Yesterday I took the 260 for a long, long drive ending with the fan clutch ceasing.

I’ve dismantled the fan clutch, cleaned out the gunk with carb cleaner, got it turning freely although with a slight drag and filled with 20/50 oil (will get some silicone oil and do again if worth keeping this clutch) and reassembled.

I’m not sure of the best way to test if it’s working properly. I’ve done the newspaper test at idle and the fan slows down marginally, but doesn’t stop spinning. When spinning the blade by hand with the engine stopped and cold it spins one blade short of a full revolution.My understanding is that at XXXX? rpm the clutch should disengage and this can be heard by a change in sound, i.e. the blade slightly slowing. Can someone point me in the right direction please? I’m not sure on how many times it should spin freely with the engine stopped and the RPM at which the clutch disengages.

Many thanks

Tim

 

[jonbills]

I don't think it's 'real' clutch, it's a viscous coupling - so when cold it spins slowly compared to the engine speed (and you can stop it with a rolled up newspaper) and as it heats up it becomes stiffer, so ultimately it is effectively locked to the rotation speed of the water pump and if you stick your newspaper in it i'll chop it up.

But that is my generalised view of viscous fans - the Datsun one may be different or more complicated.

 

[Huw]

I would look at replacement, Mr F at MJP should sort you out. However, RockAutos also sell them for about $30 plus import cost etc
https://www.rockauto.com/en/catalog...88000,cooling+system,radiator+fan+clutch,6812

Also it really should be filled with a silicon oil and they cut out at around 2500rpm when the engine is up to temp. It has a bimetallic strip on the front (the coil looking thingie) that shunts the oil flow around inside to reduce its spin. I can scan the s130 service manual if you like I think the unit is similar in operation.

Huw

 

[AliK]

Ceased Fan Clutch

Nice find Huw! What's the difference between the standard duty and the four seasons!?

From the FSM ....

 

[TimW]

I don't think it's 'real' clutch, it's a viscous coupling - so when cold it spins slowly compared to the engine speed (and you can stop it with a rolled up newspaper) and as it heats up it becomes stiffer, so ultimately it is effectively locked to the rotation speed of the water pump and if you stick your newspaper in it i'll chop it up.

But that is my generalised view of viscous fans - the Datsun one may be different or more complicated.

Great, thanks JB. Tried again when cold and unable to stop fan with news paper.

I would look at replacement, Mr F at MJP should sort you out. However, RockAutos also sell them for about $30 plus import cost etc
https://www.rockauto.com/en/catalog...88000,cooling+system,radiator+fan+clutch,6812

Also it really should be filled with a silicon oil and they cut out at around 2500rpm when the engine is up to temp. It has a bimetallic strip on the front (the coil looking thingie) that shunts the oil flow around inside to reduce its spin. I can scan the s130 service manual if you like I think the unit is similar in operation.

Huw

Brilliant, thanks Huw. I'm not noticing any difference when I rev and hold past 2,500rpm, say to 3,000 / 3,500. Couple this with JB's info ie fan not stopping when cold, seems my clutch is ca-putt.

Thanks for the link, I'll contact Mr.F.

Yes, if you could scan the info that would be great, much appreciated

 

[TimW]

Cheers Ali, thanks a lot mate

So.. hope I'm not being daft here, the max rotation/speed of the fan is 2,500rpm.

 

[Huw]

Ali beat me to it, the info in my service manual is the same.

Cheers

Huw

 

[TimW]

Cool, thanks Huw.

I'm not noticing any difference when I rev and hold past 2,500rpm, say to 3,000 / 3,500. Couple this with JB's info ie fan not stopping when cold, seems my clutch is ca-putt.

Durh.. to clarify, what I meant to say is that the fan rotates at engine speed at doesn't seem to settle down to 2,500 rpm when I hold the rpm at 3,500. Fan speed seems to climb with RPM past 2,500 and beyond

 

[Huw]

No problem. New Tem-coupling time Tim, wouldn't want that failing on you when driving about.

 

[AliK]

Ceased Fan Clutch

Cheers Ali, thanks a lot mate



So.. hope I'm not being daft here, the max rotation/speed of the fan is 2,500rpm.

Pleasure mate! Huw was being slow

Actually this is a topic close to my heart - I can't stop my fan at cold / idle either although I can slow it down a few RPMs. I think Tim and I may be losing a couple of BHP to spinning air. I wonder if it'll reduce my oil consumption

Edit: the reason I also started thinking of this is that I'm about to replace my leaking water pump and may as well do the job once and replace the clutch at the same time - Tim have you thought of replacing the water pump too?

 

[AliK]

Anyone know why are the rock auto ones half the price of the ones listed on MSA (z store) site!? Is the quality really that much better!?

 

[TimW]

It has been a while since my last post on subject, but I'm a little further forward

(much going on... finished en-suite.. lots of brownie points.. currently installing a new kitchen.. aye, it’s part of my master plan in readying my garage workshop/free domestic time. haha.)

Installed new fan clutch plus new water pump as suggested.

But.... temperature climbs to say 2/3rds of dial after a good thrashing or in congested traffic. Idle for a period of time and temp goes back down to 50/50, slap bang in centre of dial as it’s always been. During normal drive (i.e non stop/start) temp dial stays at slightly above 50/50, which is marginally above the bang on 50/50 it was before fan replacement. Start from cold, idle for XXX mins and beyond and temp gauge does not go beyond 50/50.

Temp seems higher than before. Normal non congested drive... turn engine off when dial is at 50/50.. leave for couple of mins... turn ignition on and temp gauge climbs to 2/3rds regardless of it being at 50/50 when engine was stopped. It takes about 10/15 mins too cool down to 50/50 with engine stopped, thus I assume engine is running hotter than it used to

This is a new phenomenon; the car has always been bang on 50/50 on dial since owned, regardless of traffic conditions, that is until installation of new fan clutch.

Thinking;

Hmm.. At a guess.. The old fan clutch had ceased so it could have been turning at higher revs on idle at 900rpm and/or through rev range prior to its ceasure, thus giving extra cooling and masking a problem.

Either faulty replacement fan clutch OR..

Timing too far advanced; - Changed from 36 degrees at 3k RPM to 32 - No difference
Running too lean; - Reset the carbs with extra half turn to make richer – No difference
Loose Fan Belt; - Checked and set at 10mm deflection – No difference

Thinking;

Put back in the old fan clutch which I had dismantled and un-ceased and see if temp still climbs. Can’t think of anything else.. smh..

The replacement fan clutch looks decidedly less substantial than the original.

Any thoughts please Chaps, I’m at a loss as to what to do or check next other than look for an OEM fan clutch?

Cheers

Tim

 

[jonbills]

I think it's normal ish for temp to rise after you switch off, but should cool quickly when started again.
I'd guess either thermostat not opening properly or rad blocked up.

 

[Moriarty]

Apologies for being a little pedantic but the correct term is seized not ceased
I know it may not matter to some but maybe one day someone will search for "seized fan" and consequently not find this thread....

 

[Rob Gaskin]

My first reaction - I don't think the fan clutch will be the problem. I may be wrong but I have never worried too much about them as long as the fan spins well. These fans are very efficient.

I think your 'change' may be due to something else. Have you put enough coolant back in?

Do you have an air-lock?

 

[TimW]

Apologies for being a little pedantic but the correct term is seized not ceased
I know it may not matter to some but maybe one day someone will search for "seized fan" and consequently not find this thread....

No worries.. I stand corrected.. Not sure, will check if I can change thread title somewhere.

I think it's normal ish for temp to rise after you switch off, but should cool quickly when started again.
I'd guess either thermostat not opening properly or rad blocked up.

Thanks JB.. Forgotten about the thermostat.. durh!.. Will take it out and go for a spin.

My first reaction - I don't think the fan clutch will be the problem. I may be wrong but I have never worried too much about them as long as the fan spins well. These fans are very efficient.

I think your 'change' may be due to something else. Have you put enough coolant back in?

Do you have an air-lock?

Thanks Rob..

The only thing is that nothing else was changed prior to pump and fan installation. Temperature was fine.

Yes, should be enough coolant. I'd changed the coolant a few months back, what came out this time went back in plus a little more. How would I know if I had an air lock?

 

[Rob Gaskin]

I've edited the Thread title.

Is the heater valve open i.e. water circulating?

 

[Huw]

Its sounds like thermostat like Jon stated or crud in the rad. Have you replaced it lately and do you have the correct one?
http://zclub.net/forum/showthread.php?p=271538&highlight=thermostat#post271538.

Its unlikely to be the fan.