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Around 2014 I replaced all belt at the front. In order to do that, I removed the fan. It can be taken out from the top. It is fiddly but it can be done. I think I loosend the bolts that hold the radiator pack in place to gain a bit more access.
Btw., the viscous clutch couldn't care at all about if the ignition was on or not There is no electrical connection to it. The only thing is, ignition off means engine is off and no risk of touching some moving blades...
I'd either get a new one (cost something like £150 or so from SNG) or a good used one. And while you're at it, maybe see if the new black fan fit the new unit better... Just a suggestion.
Thumbs up!
Hi Daim
Cheers!
And you're right! that Thermostat is for the AUX Fan!
What would cause a Viscous Fan to 'Lock Up' as they usually go the other way and Spin round.
NOTE TO SELF!
Do NOT, NOT, NOT, Try and turn the Fan Blades by hand on the Engine!
You know what happened last time, I nearly broke the Chain Tensioner and thought that I'd got a dropped Valve!
I did replace both the fan and clutch a year ago and I think I did have to separate the fan from the clutch first. And I'm afraid you need to rotate the fan in order to access all the nuts/bolts - maybe slacken the belt a little bit first.
If I had to do it now I would go with an electric fan. The mechanical fan/clutch makes quite some noise/roar for a few minutes after a cold start and also after stopping for a while e.g. at a traffic light.
As I've got to pull it all to bits, I was wondering if I ought to invest in one of those Silent Electric Fans, that fit inside the Shroud like you've got on your Car.
Did you finish doing your evaluation?
Please could you give me the make and model again, so I can do the maths and weigh up the options.
I wrote up a post on it. At the office. Its still sitting there unposted after work picked up something fierce. I'll post it when I get in today.
What would cause a Viscous Fan to 'Lock Up' as they usually go the other way and Spin round.
I've never examined a failed unit to determine exactly how the seizing-up occurs. Nor, frankly, had the inclination to do so. I always just sorta assumed that wear of the moving parts becomes significant enoughh that said parts are no longer properly held in position. When this occurs they bind-up and eventually seize.
There's nothing you can do to prevent fan clutch failure.....be it the seize-up type of failure or the loosey-goosey type of failure. When it happens, it happens.
Someone will come along with a better explanation
Here's an exploded view of a typical fan clutch, in case you were curious
AlL my cars with viscous clutch fans seized up. Free spinning is new for me.
Most commonly - that I know of - is rusting of the bimetal strip which engages/disengages the clutch. One side of the strip goes and the result is that the clutch is permanently engaged.
I did replace both the fan and clutch a year ago and I think I did have to separate the fan from the clutch first. And I'm afraid you need to rotate the fan in order to access all the nuts/bolts - maybe slacken the belt a little bit first.
If I had to do it now I would go with an electric fan. The mechanical fan/clutch makes quite some noise/roar for a few minutes after a cold start and also after stopping for a while e.g. at a traffic light.
Hi Jp
This time I did slack the belt off first, in order to turn it without turning the engine and I also put on Twin Electric Fans but they were so darn noisy that I took those off and went back to Mechanical.
Then the Fan Clutch Seized up!
Which means a Total Strip down back to Square one and beyond, although I think that Jig Jag may have come up with the Perfect Solution.
AlL my cars with viscous clutch fans seized up. Free spinning is new for me.
Most commonly - that I know of - is rusting of the bimetal strip which engages/disengages the clutch. One side of the strip goes and the result is that the clutch is permanently engaged.
I managed to get the Fan off but for some strange reason this time I decided to leave it attached to the Fan Clutch and then take it out in one piece.
This turned out to be a massive mistake, as the gap wasn't big enough to get it out of the Car, without releasing the Fan Shroud at the Top. (which I did)
As the gap between the Fan Shroud and the Rad was still too small, I took the Top Panel off but still no dice without undoing the bottom of the Fan Shroud.
Except I cannot undo those bolts unless I remove the Spoiler Under tray.
I managed to get the Fan off but for some strange reason this time I decided to leave it attached to the Fan Clutch and then take it out in one piece.
That's not strange. That's the typical method
This turned out to be a massive mistake, as the gap wasn't big enough to get it out of the Car, without releasing the Fan Shroud at the Top. (which I did)
As the gap between the Fan Shroud and the Rad was still too small, I took the Top Panel off but still no dice without undoing the bottom of the Fan Shroud.
Except I cannot undo those bolts unless I remove the Spoiler Under tray.
So, what are you waiting for? I believe I mentioned it might be necessary to remove the fan shroud attachments. I wasn't referring to just the easy-to-reach ones on top!
The Nightmare continues..........
Whenever you work on one of these V12s you simply have to resign yourself to removing lots of 'stuff' to reach whatever it is you need to repair. Any attempts at short cuts in this regard will only make things worse, trust me. The car will fight you. And the job becomes a nightmare, yes.
I managed to get the Fan off but for some strange reason this time I decided to leave it attached to the Fan Clutch and then take it out in one piece.
This turned out to be a massive mistake, as the gap wasn't big enough to get it out of the Car, without releasing the Fan Shroud at the Top. (which I did)
As the gap between the Fan Shroud and the Rad was still too small, I took the Top Panel off but still no dice without undoing the bottom of the Fan Shroud.
Except I cannot undo those bolts unless I remove the Spoiler Under tray.
The Nightmare continues..........
You could remove bracket that holds the fan. It is only held in place by 4 nuts/screws. As said, I managed to remove mine before...
At the same time, check the bearing for the fan bracket. Mine is dead or better was dead. It is a pita to get a new one. I seem to have at least by my knowledge, the last original bearing available... Probably more to come yet but that is an important bearing. If the car stood 17 years, it is worth checking them. Mine were dead after 78.000 miles, which is nothing for a bearing as sealed as this is.
Fan clutches seizing up is not particularly unusual.
Not a terribly difficult fix; you've been thru worse.
In a nutshell....
Remove four nuts holding the clutch to engine. Fiddly task; loosen one nut a few turns and go to the next; loosen a few turns and go to the next; repeat, repeat until the clutch can be shifted forward enough to actually remove the nuts.
Remove fan and clutch from the car as an assembly and take to the workbench.
Remove old clutch from the fan; install new clutch; reassemble.
Replace fan itself if in any doubt as to age or condition.
As I recall you'll have to remove the fan shroud attachments/fasteners so the shroud can be shifted aside a bit to allow working room and allow the fan and clutch assembly to be wriggled out.
Have extra nuts on hand. I can almost promise you'll drop a few into the abyss of the engine bay, never to be seen again.
It isn't the most pleasant job but you'll get through it!
Cheers
DD
I just did this as replacing all the belts it is much easier if you take the fan and fan clutch assembly out of the way...
a Tip after dropping two nuts and retrieving them from under the XJS:
use the Wiggle of the fan to Pinch the nut in place until you can slip them on the stud and then turn them to get them started on the thread....
after I figured out to use the fan to pinch the nuts (like a third hand) in place everything went faster... (it is a claming moment leaning over the fender and engine to get this done ... remember breath easy stay calm drink beer)
the first nut will take the longest and each one in turn goes quicker, the last taking like 30 seconds... (to get them started that is)
do not forget the lock washers... even thought the design precludes a failure that would damage any thing... ( there is NO was all four nuts could back off equally all at the same time with out you hearing some kind of ruckus...)
Last edited by Jonathan-W; 08-07-2017 at 10:46 AM.
After some weeks of continuous Rain and bad Weather, the Sun was finally Shining at last and so we went for a Test Drive.
Which didn't end well as the Fan Clutch seized up, which meant that we had to limp home.
So today was the day I removed it to see what was wrong, as it could have been something simple.
Like one of the nuts coming loose and then touching the Fan Boss, which could have made it lock up.
Just out of interest I wanted to know if I had enough tools in the Car to do this job.
Since I started to cut down on all the tools I carried around in the 'Cubby Box'
What's in the Box?
My new Socket Set should come in useful
'Sods Law' decrees that the Spanner I need is missing, so I had to make one to undo the nuts on the Fan.
But first I needed to raise the Bonnet/Hood up into the Air for better access.
Which meant unbolting the Bonnet/Hood Struts, a relatively easy job that only took a few minutes.
First I had to remove the Bonnet/Hood Struts for easier access
Then I lifted the Bonnet/Hood up into the Air and tied it off.
Bonnet/Hood up in the Air to give easier access
Undoing the Fan Boss Nuts was a bit of a Nightmare, as I expected it would be
I had to remove the Top Panel as well as the Shroud to get the Fan out
It was a bit of a struggle but I finally got there in the end
Empty space where the Fan Shroud used to be
Fan Shroud and Fan out at last, where I found that the Fan Clutch had locked up rock solid.
The Fan Clutch was locked up Rock Solid, so that the Fan wouldn't turn.
Out at last!
So now I've got to find a New Fan and then put it all back together.
If removing the Fan was hard, removing the Fan Shroud was harder but I got there in the end
The Fan Shroud was a PIA to remove, as I had to undo the lower fixing bolts which meant removing the under tray which I had only refitted a few Weeks ago
Now all I've got to do is to get a new Fan Clutch, unless I go Electric with a similar set up to Jig Jag.
the solution to a noisy Fan...
1st the blade design... (look for a wonky unevenly spaced blade on the FAN) (this reduces Noise)
2nd on Electric fans... no not go with relays... ( very all or nothing) go with a variable fan speed controller...
Derale 16795 PWM Electric Fan Controller Push-In Probe
that is what I would have done if I did have a spare fan clutch on the shelf that cost me about $15... mine is ok and I have the spare in the wings...
(though I would like the torque it would free up..)
Last edited by Jonathan-W; 08-08-2017 at 10:32 AM.
08-07-2017, 01:42 AM
There is no electrical connection to it. The only thing is, ignition off means engine is off and no risk of touching some moving blades...
I believe I mentioned it might be necessary to remove the fan shroud attachments. I wasn't referring to just the easy-to-reach ones on top!
