Un-doing the viscous fan nut…..arghhhh!
Moto One asking about removing his alternator reminded me of the fun & games I had when I replaced the radiator on my ’03 model (BMW M62 engine) recently. Everything was perfectly straightforward and went very smoothly except for the removal of the viscous fan. Obviously I knew that the nut had a left-hand thread and I managed to get hold of a thin spanner (32mm across flats) easily & cheaply from my local car parts place. The problem was how to stop the water pump pulley from rotating while I slackened off the nut.
From reading the BMW forums it appeared that many people got away with simply ‘shocking’ the nut without even having to hold the pulley. I had no such luck. In fact I was surprised how little torque you could place on the nut before the belt slipped.
Next I tried making up a holding tool for the pulley as described by the guy in this post : http://www.bimmerboard.com/forums/posts/119957
Unfortunately this ‘single hole’ tool didn’t work for me – the viscous fan nut still refused to budge and the tool kept slipping off the pulley bolt heads.
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Next, I looked up details of the official BMW tool 11 5 050 which appears to be a ‘twin hole’ tool :
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so I made my own and, well, it just bent like a banana and the nut still refused to budge :
![Image]()
Obviously the bar needed hardening.
In the end I gave up and shelled out for the official Land Rover service tool (part no. LRT-12-215) which is a ‘triple hole’ tool.
I’ve placed an iPhone next to it in the photo below to give an idea of scale – it’s huge :
![Image]()
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Not surprisingly the fan nut came loose with one tap when the pulley was being held rigidly by this monster!
I got a new OEM radiator (i.e. manufactured by Behr, as was the original one that I removed) for £162 and the pulley holding tool cost a hefty £57 incl. postage, so the total job cost around £220 which I didn’t think was so bad overall. (LR dealers charge over £350 just for the radiator, without fitting)
I used the tool again when I replaced the tensioner idler pulley set for the ancillary drive belt so, despite its cost, I think it’s a handy thing to have around the workshop.
I wondered if anyone else had had more success than I at removing the viscous fan nut without having to resort to the expense of buying a special tool? In fact I seem to remember someone on this forum mentioning that he managed to change his radiator without even removing the fan?
Phil
Moto One asking about removing his alternator reminded me of the fun & games I had when I replaced the radiator on my ’03 model (BMW M62 engine) recently. Everything was perfectly straightforward and went very smoothly except for the removal of the viscous fan. Obviously I knew that the nut had a left-hand thread and I managed to get hold of a thin spanner (32mm across flats) easily & cheaply from my local car parts place. The problem was how to stop the water pump pulley from rotating while I slackened off the nut.
From reading the BMW forums it appeared that many people got away with simply ‘shocking’ the nut without even having to hold the pulley. I had no such luck. In fact I was surprised how little torque you could place on the nut before the belt slipped.
Next I tried making up a holding tool for the pulley as described by the guy in this post : http://www.bimmerboard.com/forums/posts/119957
Unfortunately this ‘single hole’ tool didn’t work for me – the viscous fan nut still refused to budge and the tool kept slipping off the pulley bolt heads.
Next, I looked up details of the official BMW tool 11 5 050 which appears to be a ‘twin hole’ tool :
so I made my own and, well, it just bent like a banana and the nut still refused to budge :
Obviously the bar needed hardening.
In the end I gave up and shelled out for the official Land Rover service tool (part no. LRT-12-215) which is a ‘triple hole’ tool.
I’ve placed an iPhone next to it in the photo below to give an idea of scale – it’s huge :
Not surprisingly the fan nut came loose with one tap when the pulley was being held rigidly by this monster!
I got a new OEM radiator (i.e. manufactured by Behr, as was the original one that I removed) for £162 and the pulley holding tool cost a hefty £57 incl. postage, so the total job cost around £220 which I didn’t think was so bad overall. (LR dealers charge over £350 just for the radiator, without fitting)
I used the tool again when I replaced the tensioner idler pulley set for the ancillary drive belt so, despite its cost, I think it’s a handy thing to have around the workshop.
I wondered if anyone else had had more success than I at removing the viscous fan nut without having to resort to the expense of buying a special tool? In fact I seem to remember someone on this forum mentioning that he managed to change his radiator without even removing the fan?
Phil
