I have had a cooling issue with my car for a while, which I initially thought was the viscous clutch on the fan. It was and it wasn't!
The clutch was not operating correctly, but the main culprit was a leaking thermostat which was over-cooling the engine.
I have changed the viscous clutch for a new one, then changed it back to the old one and finally fitted a new thermostat today. All is now working as it should.
During this 'fiasco' I have asked for much advice on various BMW forums and have been offered various knowledge of the M54B30 cooling system.
After now getting my cooling system 100% working as it should, I have learned the following.
NB: the temperatures I am quoting are +10c on the readings from my scanner, as they were clearly wrong. I am confident that the temps quoted are pretty accurate (from a mixture of my gauges and oil temps).
So here are my findings......
The thermostat on an M54B30 is electrically operated. It is metered, ie it opens and closes at varying amounts to control the coolant temperature to a small band. The band is between around 92c and 90c. The thermostat is also mechanical. This is just a 'failsafe' for if the electrical system goes wrong. The mechanical opening temperature is 97c.
The A/C electric fan acts as an auxillary, emergency, fan only if the viscous can't cope or is faulty. This cuts in at 105c and shuts off at 95c.
I was told many things recently about the M54 cooling system, some of which I think are wrong, so I thought I should share them....
"The M54 runs really hot; around 97c and higher". This is wrong. The engine will only run that hot if you let it. It was not designed to.
"Just delete the viscous fan and rely on the electric, it doesn't do anything useful". This is also bad advice. As I have found out, the electric fan is an 'emergency only' auxillary, designed to cool the engine when it gets to it's operating upper limits. And it doesn't cool it low enough, so the engine is always running 'hot'!
I have also learned that the BMW coolant temperature gauge is a 'guide' only. The gauge works in 'blocks', so the coolant temperature can swing 10c or more and the gauge won't move. This, presumably, was done to stop people panicking if the engine gets quite warm on a hot day. Which is fine, as long as your coolant system is operating correctly! I don't have BMW gauges anymore, so mine give a true indication (as long as they are accurate).
I hope this helps some people.
The clutch was not operating correctly, but the main culprit was a leaking thermostat which was over-cooling the engine.
I have changed the viscous clutch for a new one, then changed it back to the old one and finally fitted a new thermostat today. All is now working as it should.
During this 'fiasco' I have asked for much advice on various BMW forums and have been offered various knowledge of the M54B30 cooling system.
After now getting my cooling system 100% working as it should, I have learned the following.
NB: the temperatures I am quoting are +10c on the readings from my scanner, as they were clearly wrong. I am confident that the temps quoted are pretty accurate (from a mixture of my gauges and oil temps).
So here are my findings......
The thermostat on an M54B30 is electrically operated. It is metered, ie it opens and closes at varying amounts to control the coolant temperature to a small band. The band is between around 92c and 90c. The thermostat is also mechanical. This is just a 'failsafe' for if the electrical system goes wrong. The mechanical opening temperature is 97c.
The A/C electric fan acts as an auxillary, emergency, fan only if the viscous can't cope or is faulty. This cuts in at 105c and shuts off at 95c.
I was told many things recently about the M54 cooling system, some of which I think are wrong, so I thought I should share them....
"The M54 runs really hot; around 97c and higher". This is wrong. The engine will only run that hot if you let it. It was not designed to.
"Just delete the viscous fan and rely on the electric, it doesn't do anything useful". This is also bad advice. As I have found out, the electric fan is an 'emergency only' auxillary, designed to cool the engine when it gets to it's operating upper limits. And it doesn't cool it low enough, so the engine is always running 'hot'!
I have also learned that the BMW coolant temperature gauge is a 'guide' only. The gauge works in 'blocks', so the coolant temperature can swing 10c or more and the gauge won't move. This, presumably, was done to stop people panicking if the engine gets quite warm on a hot day. Which is fine, as long as your coolant system is operating correctly! I don't have BMW gauges anymore, so mine give a true indication (as long as they are accurate).
I hope this helps some people.
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