Viscous Fan Delete Modification

[Dino D]

Cheers mate, I know she runs slightly cool and drops when coasting down long hills with the viscous on so its most prob the thermostat, so she will get some TLC once the season is over.

Tap on the image to expand works on my iPhone.

A job I've got to do on mine so ordered a water pump, fan blade assembly, belts and pulleys. I have a new non oem viscous which I bought years ago in ignorance not knowing if it will be up to task but can stop my old one at by grabbing the fan blades with protective glove at cold.

Don't forget the thermostat and the housing (the 2.8 has a plastic one which cracks, I know). The M may already have the aluminium housing. In that case I think you need fresh gasket for the housing when changing the stat.

 

[Nodzed]

In my experience it didn't work that way - two couplings failed (both genuine) and in both cases they didn't lock, instead they never locked up at all so the fan did nothing. Because mybaux fan was wired incorrectly in America it never kicked in so it started getting hot. On another occasion the viscous fan lost blades and nearly pierced the radiator.

Even it were locked to blow all the time I'm not sure it can cause a low reading on the dash - the dash gets it temp reading from the sensor in the head - the coolant to the head is controlled by the thermostat which remains closed if the coolant was not hot enough (can't remember what the temp is).

I remember reading that in normal temps it's not possible for the fan reduce the coolant temp so far that the thermostat won't open.

Maybe the thermostat is stuck open hence getting cool readings with the viscous in place?

Yes I agree there is an issue with my stat, but the aux fan is a different issue, but I have difficulty agreeing on the viscous, all manufactures designed their viscous to lock up if the oil is lost (blades breaking is a totally different issue) a viscous blowing at full engine speed (locked up) (and something it would never do in normal operating conditions and would make such a noise at revs you wouldn't hear the engine) can lower temp to below thermostat opening (or near), your gauge will be up and down like a yo yo. Fords were a real pain for this in the late 80s early 90s, their viscous fans failed for for a past time, I had several let go and always failed to safe.

 

[Nodzed]

Tap on the image to expand works on my iPhone.

A job I've got to do on mine so ordered a water pump, fan blade assembly, belts and pulleys. I have a new non oem viscous which I bought years ago in ignorance not knowing if it will be up to task but can stop my old one at by grabbing the fan blades with protective glove at cold.

Yes the fan works as a slipping system, the hotter the engine the harder (faster ) the fan turns so you should be able to stop it but I wouldn't recommend it as you can damage the blades and viscous.

 

[Dino D]

I don't think mine lost oil, they just stopped locking up.

I've got the last one still in the garage somewhere - would and oil leak be obvious i.e. oil over it? It was pretty clean when I took it out. It was just not locking up. Was around a year old from BMW.

 

[Althulas]

Too true should have used a news paper first, I knew the risk of damaging the blades but the ///M not being run at present while I'm in exile and under cover due to knackered roof another to the spends list

 

[Nodzed]

I don't think mine lost oil, they just stopped locking up.

I've got the last one still in the garage somewhere - would and oil leak be obvious i.e. oil over it? It was pretty clean when I took it out. It was just not locking up. Was around a year old from BMW.

That's strange mate unless BMW don't design theirs that way but I have never heard of a viscous going limp so to speak!

Anyway my point was in the beginning, the BMW engineers know more about cars than me so viscous back on and leave well alone and stop messing with German engineering.

 

[roadvoyager1]

Had a look at my auxiliary fan guard. It fully covers the fan blades so I think I am safe on that one.

IMHO for normal use on a 2.8 in the UK the auxiliary fan is adequate. For extreme running more cooling may be required. For example, if cruising alpine passes in the height of summer refitting the viscous coupled fan would be a good idea.

 

[Lee]

Let me confuse things further. Most of the time you guys saw me doing doughnuts I weren't running a vicious fan and my M was used to her full potential

 

[Nodzed]

Had a look at my auxiliary fan guard. It fully covers the fan blades so I think I am safe on that one.View attachment 39590

View attachment 39591

IMHO for normal use on a 2.8 in the UK the auxiliary fan is adequate. For extreme running more cooling may be required. For example, if cruising alpine passes in the height of summer refitting the viscous coupled fan would be a good idea.

Well that's a much better design than the one on my ///M as you can see the guard ends at the lower PS cooling pipe, strange why it should be different.

 

[Nodzed]

Let me confuse things further. Most of the time you guys saw me doing doughnuts I weren't running a vicious fan and my M was used to her full potential

@Lee I haven't had any issues before and I have driven her hard on times, but it was a very long steep twisty road and on full chat all the way up, but she didn't like it, and to be fair I had no problems for the rest of the day either. What I got most concerned about was how long it took to come back down once I'd noticed and eased off. So better safe than sorry until I can do a cooling system service