M54 engine viscous fan. Not sure if I have an issue.

the Nefyn cat said:
Bear in mind that a car sat ticking over will never heat up as much as when it's being driven, so any amount of sitting running for 90 mins won't bring out any problems.
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I know but with something like this there is no other way to test it (that I know). I can't drive down the road sitting on the engine and keeping an eye on it! For a start I would burn my bum. :D
 
I've got one of those Creator 310s that gives live readings as you go, pretty sure it does engine temperature, but I'm miles from home so can't be sure. Might be better than leaving it ticking over for hours, never does an engine any good.

Just noticed that you could have asked for one as a birthday present from some nearest-and-dearest, bit late I know. Still, that's the power of the edit button.
 
the Nefyn cat said:
I've got one of those Creator 310s that gives live readings as you go, pretty sure it does engine temperature, but I'm miles from home so can't be sure. Might be better than leaving it ticking over for hours, never does an engine any good.

Just noticed that you could have asked for one as a birthday present from some nearest-and-dearest, bit late I know. Still, that's the power of the edit button.
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I have a creator 410 but have only plugged it into the round OBD in the engine bay. Maybe I should try the SCART socket? I will need to cut a few cable ties, as it is now buried up under the dash. ;)
 
The OBD11 (under dash) socket reads a whole lot more, and this being a Z3 you'll be needing it. There's also something in the rules of cars about the sockets' location, don't know if it applies to rebodies. It only takes one jobsworth type to get uppity about it......:whistle:
 
the Nefyn cat said:
The OBD11 (under dash) socket reads a whole lot more, and this being a Z3 you'll be needing it. There's also something in the rules of cars about the sockets' location, don't know if it applies to rebodies. It only takes one jobsworth type to get uppity about it......:whistle:
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My Z3 has a little blanking plate under the dash where the ODBII 'could' go but, being a late pre-facelift, it didn't have the actual ODBII socket there at all. AFAIK the socket only came under the dash in post facelift cars. Pond's is likely a facelift but I wouldn't expect many Jobsworths to know, or care, which Z3s should or shouldn't have an under-dash connector.
 
The round 20-pin connector is BMWs own diagnostic connector. Everything that BMW techs communicate with is via this connector. The SAE standard 16-pin OBDII connector is a legislated requirement specifically to diagnose emissions related issues. This connector, communication method and diagnostic features are common for all manufacturers and was mandated in the USA in 1995, with Europe coming late to the party in 2000. OBDII is very powerful for diagnosing emissions related problems - typically involving engine and transmission - a lot of very smart people have created robust diagnostics that are common across all passenger vehicles.
Most manufacturers gradually moved their own diagnostics to the standard port to prevent duplication and used the OBDII standard for all diagnostic features.
 
I definitely have a cooling issue, putting the viscous fan saga aside.

The car takes an age to reach full operating temperature when driving (25 miles today at ambient of 14c).
I am thinking the stat is 'letting by'. Does this make sense on an M54 engine?
 
Pond said:
I definitely have a cooling issue, putting the viscous fan saga aside.

The car takes an age to reach full operating temperature when driving (25 miles today at ambient of 14c).
I am thinking the stat is 'letting by'. Does this make sense on an M54 engine?
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I don't have or know that engine but engine staying way below working temp, in any engine, points to thermostat stuck open.
 
All sorted after weeks of chasing the cooling issue. My thermostat was leaking!
I have learned a great deal about the M54B30 cooling system recently so will post a new thread as it may be of use to some.
 
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Sorry to pop this one back to the top.

@Pond Your viscous fan adventures. Looking back in this thread it looks like you fitted a new one then you went back to the old one - new one came in too soon or something?

How noisy are these viscous fans supposed to be? I don't hear mine when the engine is cold - it's just free wheeling. But when the engine is hot I can hear it when driving slow but not worryingly loud - but today when backing into the confines of my garage I notice how loud it is. Fan louder than the engine if you know what I mean. Doesn't sound right to me.

Genuine one from BMW is £200 quid or thereabout. Cheapo one off of fleebay 30 quid ish.

Just don't want to change it if it's gonna make things worse.
 
A noisy viscous fan clutch typically indicates a stuck clutch or worn internal bearings. When it seizes, it forces the cooling fan to spin constantly at maximum engine speed—producing a loud, jet-engine roar. The fan must be replaced immediately to prevent catastrophic blade failure or damage to the water pump.

Quick Diagnosis Steps
To confirm your fan clutch is the culprit, check the following:
  • Cold Start Roar: Start your vehicle cold and rev the engine. If the fan instantly roars and blows hard air, the clutch is seized.
  • The "Spin-Down" Test: Turn off a fully warmed-up engine. A healthy fan will stop rotating almost immediately (within 1-4 seconds). If it spins freely for a long time, it is slipping; if it screeches or grinds, the bearings are shot.
  • Viscous Drag Test: With the engine completely off and cold, gently try to spin the fan by hand. It should have some resistance but turn smoothly. If it's incredibly stiff or won't turn at all, the clutch is locked up

Why It Fails
  • Silicone Fluid Degradation: The internal silicone fluid thickens and locks up, or leaks out completely.
  • Worn Bearings: Internal pulley bearings degrade, causing harsh growling, squealing, or grinding metallic noises.
Often, viscous fan clutches cannot be rebuilt and require a full replacement. To determine the best way to move forward:
  • What is the year, make, and model of your vehicle?
  • Is the fan roaring continuously, or are you hearing squealing/grinding?
Knowing these details will help outline the exact replacement steps and if you should also inspect the water pump or drive belts for damage!

View: https://www.youtube.com/watch?v=gJQs-6yt1E0&t=6
 
Thanks - As I said, the fan free wheels when cold. No noise - no roar. When the engine is hot, idling in this heat, the fan does eventually engage and I hear it. The engine does not overheat no matter how long I leave it idling. So the fan is working. It passes all those tests.

The fan 'works' it works fine doing what it should. Engages/disengages etc.

It's just the amount of noise when it's engaged. It just seems too noisy. So, my question, how noisy are they supposed to be?
 
Duncodin said:
It's just the amount of noise when it's engaged. It just seems too noisy. So, my question, how noisy are they supposed to be?
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When you say 'noisy', are you talking about the 'roar' of the air, or a mechanical noise?
I eventually fitted a new one (as I bought one) and it can 'roar' occasionally even when the engine is cool. That, I presume, is the fluid starting move around. Obviously it does nothing, as the thermostat is closed, but it will still roar a bit then settle down.

At tickover the fan running full pelt is only spinning at idle revs (800rpm ish) but it can still roar.

I read somewhere that the viscous fan only runs up to 2700rpm, if the engine is running faster the fan won't. This is so that the fan doesn't rip itself apart if you redline the engine apparently.

As said above, if you can hear the fan, it's working, so don't worry.
 
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