My car appears to be haunted. Help.
Discussion
Right that got your attention so time to explain a rather bizzare fault what has developed with my motor car.
Said vehicle is a 1995 318 iS coupe with a pretty basic specification - in fact none of the optional (back then) widgetry seems to have been specifed other than electric windows and sunroof; whihc were possibly even standard on the coupe anyway.
On to the fault. This manifests itself as a constant, quiet knocking noise from somewhere behind the main air vent in the centre of the dashboard. Almost like a finger flicking the back of the panel. It could be a worn tappet, or the timing chain, or any number of things.
But it isn't; which has left me baffled. The noise is not caused by the engine. It happens when the car is not running. It is also not caused by any mechanical part as the car does not have to be moving.
To cause the noise all one must do is put the key in and turn it to position II. I thought it may be the heater fan, but it happens when this is completely off.
The noise is intermittent. Some days it isn't there, on others it is. When the car is in motion the raised rev noise usually covers it. It can only be heard at idle or with the engine stopped but the ignition live. I think it is still there; just inaudible.
It has been going on for several months now and has no effect at all on the running of the car. When I found out that it was not the engine I ignored it, but remained baffled. I can't imagine it's a relay shuttling as they barely make any noise.
I don't believe in ghosts; so does anyone have any ideas?
Said vehicle is a 1995 318 iS coupe with a pretty basic specification - in fact none of the optional (back then) widgetry seems to have been specifed other than electric windows and sunroof; whihc were possibly even standard on the coupe anyway.
On to the fault. This manifests itself as a constant, quiet knocking noise from somewhere behind the main air vent in the centre of the dashboard. Almost like a finger flicking the back of the panel. It could be a worn tappet, or the timing chain, or any number of things.
But it isn't; which has left me baffled. The noise is not caused by the engine. It happens when the car is not running. It is also not caused by any mechanical part as the car does not have to be moving.
To cause the noise all one must do is put the key in and turn it to position II. I thought it may be the heater fan, but it happens when this is completely off.
The noise is intermittent. Some days it isn't there, on others it is. When the car is in motion the raised rev noise usually covers it. It can only be heard at idle or with the engine stopped but the ignition live. I think it is still there; just inaudible.
It has been going on for several months now and has no effect at all on the running of the car. When I found out that it was not the engine I ignored it, but remained baffled. I can't imagine it's a relay shuttling as they barely make any noise.
I don't believe in ghosts; so does anyone have any ideas?
king nightmare. Ended up being quite a good pet. 
A quick search revealed these possibilities:
'in front of the passenger above the blower fan, behind the dash, is a vent that opens or closes depending on if you are running in recirc or not. after shutting off the car it usually will move a few minutes later.'
'Wild guess here as there may not be enough detail, but check and see if the AC blower motor is still moving air when the car is turned off.
If I recall correctly, if the Final Stage Blower Motor Resistor fails, the blower motor runs at erratic speeds and can even run when the car is turned off?'
'The culprit is the small sensor blower for active ventilation of tempreture sensor in the HVAC unit. It's located right behind the left grid on the HVAC panel. Humming/buzzing noise of this blower is a well documented problem for BMW 5 and 7 series owners. But they get it really bad (loud) The possible solution is to lubricate the shaft of the impeller which can be removed from the base. '
http://www.bimmerfest.com/forums/showthread.php?t=...
'It is the blower motor "squirrel cage" rubbing on the housing. The only thing that holds in the blower motor and fan is 1 rubber lined metal strap. When you decelerate it causes the assembly to move just enough in the mount to slightly rub the surrounding plastic. Very annoying but really not a problem. It is kind of a PITA to get to fix so just crank up the stereo a bit. If you choose to fix it, you must remove the windshild wiper blades, cowl cover and blower motor fan housing cover. Just spin the fan and see what it is rubbing on and make the appropriate adjustments. Hope this helps!'
'in front of the passenger above the blower fan, behind the dash, is a vent that opens or closes depending on if you are running in recirc or not. after shutting off the car it usually will move a few minutes later.'
'Wild guess here as there may not be enough detail, but check and see if the AC blower motor is still moving air when the car is turned off.
If I recall correctly, if the Final Stage Blower Motor Resistor fails, the blower motor runs at erratic speeds and can even run when the car is turned off?'
'The culprit is the small sensor blower for active ventilation of tempreture sensor in the HVAC unit. It's located right behind the left grid on the HVAC panel. Humming/buzzing noise of this blower is a well documented problem for BMW 5 and 7 series owners. But they get it really bad (loud) The possible solution is to lubricate the shaft of the impeller which can be removed from the base. '
http://www.bimmerfest.com/forums/showthread.php?t=...
'It is the blower motor "squirrel cage" rubbing on the housing. The only thing that holds in the blower motor and fan is 1 rubber lined metal strap. When you decelerate it causes the assembly to move just enough in the mount to slightly rub the surrounding plastic. Very annoying but really not a problem. It is kind of a PITA to get to fix so just crank up the stereo a bit. If you choose to fix it, you must remove the windshild wiper blades, cowl cover and blower motor fan housing cover. Just spin the fan and see what it is rubbing on and make the appropriate adjustments. Hope this helps!'
Google [bot] said:
A quick search revealed these possibilities:
'in front of the passenger above the blower fan, behind the dash, is a vent that opens or closes depending on if you are running in recirc or not. after shutting off the car it usually will move a few minutes later.'
'Wild guess here as there may not be enough detail, but check and see if the AC blower motor is still moving air when the car is turned off.
If I recall correctly, if the Final Stage Blower Motor Resistor fails, the blower motor runs at erratic speeds and can even run when the car is turned off?'
'The culprit is the small sensor blower for active ventilation of tempreture sensor in the HVAC unit. It's located right behind the left grid on the HVAC panel. Humming/buzzing noise of this blower is a well documented problem for BMW 5 and 7 series owners. But they get it really bad (loud) The possible solution is to lubricate the shaft of the impeller which can be removed from the base. '
http://www.bimmerfest.com/forums/showthread.php?t=...
'It is the blower motor "squirrel cage" rubbing on the housing. The only thing that holds in the blower motor and fan is 1 rubber lined metal strap. When you decelerate it causes the assembly to move just enough in the mount to slightly rub the surrounding plastic. Very annoying but really not a problem. It is kind of a PITA to get to fix so just crank up the stereo a bit. If you choose to fix it, you must remove the windshild wiper blades, cowl cover and blower motor fan housing cover. Just spin the fan and see what it is rubbing on and make the appropriate adjustments. Hope this helps!'
Thanks, but as stated the noise is there with the blower fan switched off. If it isn't moving then it can't make a noise. The stuff about air conditioning doesn't apply either as the car doesn't have it fitted.'in front of the passenger above the blower fan, behind the dash, is a vent that opens or closes depending on if you are running in recirc or not. after shutting off the car it usually will move a few minutes later.'
'Wild guess here as there may not be enough detail, but check and see if the AC blower motor is still moving air when the car is turned off.
If I recall correctly, if the Final Stage Blower Motor Resistor fails, the blower motor runs at erratic speeds and can even run when the car is turned off?'
'The culprit is the small sensor blower for active ventilation of tempreture sensor in the HVAC unit. It's located right behind the left grid on the HVAC panel. Humming/buzzing noise of this blower is a well documented problem for BMW 5 and 7 series owners. But they get it really bad (loud) The possible solution is to lubricate the shaft of the impeller which can be removed from the base. '
http://www.bimmerfest.com/forums/showthread.php?t=...
'It is the blower motor "squirrel cage" rubbing on the housing. The only thing that holds in the blower motor and fan is 1 rubber lined metal strap. When you decelerate it causes the assembly to move just enough in the mount to slightly rub the surrounding plastic. Very annoying but really not a problem. It is kind of a PITA to get to fix so just crank up the stereo a bit. If you choose to fix it, you must remove the windshild wiper blades, cowl cover and blower motor fan housing cover. Just spin the fan and see what it is rubbing on and make the appropriate adjustments. Hope this helps!'
I really am baffled by this.
Its to do with the heating system and a problem with the fan or recirc electrics (nothing to do with the fan speed switch).
I've heard this noise before on E36 models and it normaly stops after a few seconds, its something to do with opening/closing the recirc/open air flow.
You need to go on e36 specific forum there will be plenty of people there who can tell you how to fix.
I've heard this noise before on E36 models and it normaly stops after a few seconds, its something to do with opening/closing the recirc/open air flow.
You need to go on e36 specific forum there will be plenty of people there who can tell you how to fix.
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