Tips for Viscous fan removal

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virtualme123

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I've got to replace my radiator and hoped I wouldn't have to remove the fan, but looks like I do. Now I have the diesel 2.5 and the information is a left hand thread. Just for sanity sake I should undo that in a clockwise direction?*

I have tried but can't see what I can hold onto to stop it turning, any tips?


Many thanks!
 
Viscous fans ALWAYS undo in the direction they rotate. Leave the belt on, put a spanner on nut and give it a sharp blow with a medium hammer.
 
Thanks for the reply. If I happen to not be able to get it off with the sharpe whack, what can I grab hold of to stop it rotating when I hit it?

Cheers!
 
virtualme123 said:
Thanks for the reply. If I happen to not be able to get it off with the sharpe whack, what can I grab hold of to stop it rotating when I hit it?

Cheers!
Click to expand...

Sharp clip never fails if done properly. There are tools available to hold it with. But maybe a bit expensive for a one off use. It is very rare that they will undo with hand pressure even when held.
 
Thanks again for all your advice, I did actually manage to use a pipe latching device with an extension on the end, then with the spanner on a couple of large whacks did it! What a happy moment that was :)

Now paroniod about overheating but first test run was temperature midway and level, my only worry is after the test sitting idol the temperature was over halfway. I'll keep an eye on it but anything I should check? Top hoses get hot and don't think there is air...

Thanks
 
Anyone else wanting to do this on a diesel you will need a 32mm spanner or a cheaper option is to get on eBay I bought the correct viscous tool for less than £6 and then once the fan was removed sold both the tool and fan on eBay.

Virtualme123 don’t worry about cooling; the temperature will rise much quicker with the fan removed. I have wired up the air-con fans to a thermostatic switch, it’s only ever kicked in once when I was on my way to Alton Towers and I was stuck in traffic for a while.
 
So just went in another test drive and thrashed it a bit, trouble is temperature started to go up and was close to red so stopped to cool down. Before I changed the radiator I hadn't had any of the usual overheating issues, do you think the previous owner did put a 100% coolant mix in? I just put 50/50...

Thanks
 
virtualme123 said:
So just went in another test drive and thrashed it a bit, trouble is temperature started to go up and was close to red so stopped to cool down. Before I changed the radiator I hadn't had any of the usual overheating issues, do you think the previous owner did put a 100% coolant mix in? I just put 50/50...

Thanks
Click to expand...

Coolant mix will make no difference to how hot the engine gets. All a more concentrated mix does is raise the boiling point a little and prevent freezing at a lower temp. What exactly have you done. You either have an airlock or you have fitted a raditor without the tank top baffle.
 
Last edited:
So have everything connected as before so assume that includes the baffle, if an air lock how do I find it and remove it?

Thanks
 
virtualme123 said:
So have everything connected as before so assume that includes the baffle, if an air lock how do I find it and remove it?

Thanks
Click to expand...

The cooling system is strange, in that hot water enters the top of the rad and cooled water also exits the top of the rad. There is a baffle halfway along the top tank. This directs hot coolant down the R/H side of the radiator looking from the front, to be cooled then up the L/H side to exit at the top. If the baffle is missing hot coolant can go directly to the outlet without going through the rad to be cooled. Trick is before you fitted rad to put a marble in one side and try to get it to roll across to the other outlet. If it does the baffle is missing or has been damaged. If it does not and is stopped half way the baffle is present. Some cheap pattern rads do not have this baffle. With engine cold remove the header tank cap. Make sure small hose from top L/H side of rad is clear of any coolant and not obstructed at either end. With engine running squeeze hoses to burp system. Top up as required. You really should have done this whilst slowly filling when you changed the rad.
 
Thanks for the detailed reply, I think I did squeeze the hoses while filling but haven't checked the baffle thing. If the baffle is missing is that a fault though and I can send it back? Surely they can't work without the baffle...


Thanks
 
virtualme123 said:
Thanks for the detailed reply, I think I did squeeze the hoses while filling but haven't checked the baffle thing. If the baffle is missing is that a fault though and I can send it back? Surely they can't work without the baffle...


Thanks
Click to expand...


No it won't work properly without the baffle. Why did you change it in the first place, was your old one leaking? If you still have the old rad try the marble trick on that just to prove the point. Also is the viscous fan locking up properly when the engine is hot? If it's just freewheeling that could also cause your problem. Stick a rolled news paper in it with engine up to temp you should not be able to stop it. If you can it's knackered.
 
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Hi Wammers, finally got round to testing it again, had vehicle running nicely at 60 and temp was stable mid way, but stopping the needle started to rise. Got back home and on tick over put the rolled paper in and it stopped... so as you say must be fan. I did have to take it off to get radiator on, do you think I broke it then or just wear?


Thanks
 
virtualme123 said:
Hi Wammers, finally got round to testing it again, had vehicle running nicely at 60 and temp was stable mid way, but stopping the needle started to rise. Got back home and on tick over put the rolled paper in and it stopped... so as you say must be fan. I did have to take it off to get radiator on, do you think I broke it then or just wear?


Thanks
Click to expand...

I don't know how you'd break a viscous fan. It's just full of a fluid that thickens as it heats so causes the fan to turn. I wouldn't blame yourself. Anyway, what does it matter, either way you're going to have to change it.

:D
 
Whilst you're in there, have you checked your water pump? The original BMW ones had plastic vanes that broke up and caused issues. There are replacement metal vaned ones. In fact that only leaves a stat and you've basically got a new cooling system.
 
Thanks for replies guys, I'll replaced the fan first and see how things look after that... ond thing after another at the moment...
 
Chances are it's the viscous fan. If the baffle is missing in the radiator then the radiator would be hot at the top and cold at the bottom so that you can check by feeling the radiator all over when temperature is up. If it is the vanes on the water pump then it would heat up very quickly and the radiator would be cold as no water would be circulating. To bleed the air out of the cooling system, just run the engine for 15 minutes or so with the heater on hot but at a low fan speed and with the radiator cap (expansion bottle ) top removed
 
Datatek said:
If your car has aircon, I can give you a mod to use the aircon condensor fans for cooling, no need then for the viscous on the diesel. PM me if you are interested.:)
Click to expand...


Datatek is correct - and I've been using this method with no problems. Plus the engine warms up faster and it gives much better access once the fan and cowling have been removed.

Plus.... sell the fan and cowl on eBay and make your morning of hard work pay for your afternoon in the sun with a beer ;-)
 
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