E36 325i jet engine whining sound, intermittent

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LCP

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Was driving back from a biz trip in Ipoh to Penang last evening, more than 70% of the way was raining. About maybe 10-20km from Juru toll, I noticed this funny and loud whining sound that come and goes, all the while I was keeping the speed and rpm steady at about 110km/h and 3000rpm... did not feel any difference to engine performance, can still accelerate and decelerate normally, no warning lights. The sound is a bit like a jet engine, also a bit like a supercharger whine (last I checked there wasn't any supercharger under the hood :) ). Sounded like from the front. It came and went away, a few times over a few minutes, very similar to the performance/rhythm of the fan clutch as the coolant temperature rise and fall, maybe more like the coolant flow stopping and starting as regulated by the thermostat. And after coming and going for a few times, it went away completely, but by then the traffic had slowed to about 90km/h. Then the traffic went into a stop-start jam because of roadworks, none of the sound came back, all the way through Juru toll, Penang bridge and into George Town, till today. All the while there was no difference in coolant temperature reading either, rock steady in the middle as usual. So, what gives? Anyone experienced this before? Is it a sign of the viscous coupling fan clutch about to go up to the big fan clutch in the sky? Or is it something more serious like my Vanos going kaboom? Or maybe some dead rat getting shredded? Or any chance that the ballz of the car (rear diff lah) about to be fried soon (although I still think that the sound came from front)? Anyway, upon reaching home, I opened up the bonnet to check, with car engine idling, no funny stains visible, no funny sounds either. An no dead rat too. The fan still has the characteristic whoosh sound when revved above 2000rpm.
 
Could it also be the fuel pump? I still have more than half a tank of fuel then.
 
Oh yes, forgot to mention that I also switched off the aircon when the sound came on, and with the aircon off, the on and off whining sound was still there... but then the bearings on the aircon compressor is always turning, only difference is there's no load when the aircon compressor is not running. Could it be bearings failure on some other pulleys... The belt on the M50 engine sure loops around lotsa pulleys.

If it is the aircon compressor bearings, what's the remedy like, replace the whole compressor or just the bearings?
 
may I ask something...

did you look at the back of ur car..?? got Jet engine flame coming out or not?

Dude..go check for leak hoses or not.
 
I'm sure as heck, no flame from the afterburner... :D

The sound is mechanical whine, not from hoses... Anyway, everything else related to hoses still works... power steering, air con, brakes, cooling system...
 
LCP;202089 said:
If it is the aircon compressor bearings, what's the remedy like, replace the whole compressor or just the bearings?

Just replace the compressor bearing.
 
Water may splash to your belt and bearing exspecially during rainning.
 
If its mechanical sounds..then I suggest you tighten all those bolts and nuts first. if not, sure some parts will blown out while:D driving....klik..klik...klak..klak...kaboom...then you be voooosh!!!:D:rolleyes:
 
In my case, it was the alternator bearing housing that gave way. Symptoms are to what you have just described. Perhaps after a longer period of time, where the whining sound is more apparent and show up more frequently, you will be cock sure of it. In the meantime, just relax :)
 
ALBundy;202153 said:
In my case, it was the alternator bearing housing that gave way. Symptoms are to what you have just described. Perhaps after a longer period of time, where the whining sound is more apparent and show up more frequently, you will be cock sure of it. In the meantime, just relax :)


If it is alternator bearing, during morning start up, most likely you will hear that whinning sound again. If i remmber correctly, to recondition your alternator which change all bearings, carbon brush, etc cost abt RM2xx.
 
Will monitor the sound, when it appears again, will try to nail down the cause. I think it will appear more frequently as things get worn out...

E3six, water splashing on belt may cause funny intermittent sound too, will take a look at the belt, if there has been slippage, the belt will show signs of wearing out.
 
Went to Chu Seng Auto just now to have the sound diagnosed, but the sound refused to come out, in fact, never, since it happened on Wednesday. Visual check on the alternator, compressor, fan and pulleys revealed no anomaly. Advise given is to continue using the car till the sound comes on again... hopefully that won't leave me stranded in some god-forsaken place...
 
Am driving E46 325i and had similar symptoms. The culprit was the fan belt bearing (RM100). But for peace of mind, I also changed the fan belt tensioner (RM145).

It's relatively easy to change, I suggest going to the workshop and get them to extract the fan belt bearing first. The just test it to see whether it spins "smoothly". If it's rough and jerky, change it...
 
For now the fan is still spinning freely and smoothly when the engine is switched off and cold. And hard to spin if the engine is switched off after reaching operating temperature for some time. Normal. And, still, the sound haven't come back yet... took the car for a 70km highway round-trip cruise yesterday, no problem...
 
LCP,

actually, the bearings and belt tensioner is not directly connected to the fan at all. The entire cooling system is a combination of pulley's all connected via the fan belt. The bearing and and tensioner are 2 parts of several other components that drive the belt which indirectly "moves" the fan. I suggest going down to your local workshop and just get them to extract and have a look at the adjusting pulley's. It should not be more than a 5 min job.

Check this site out....http://www.realoem.com/bmw/partgrp.do?model=CB32&mospid=47444&hg=11&fg=18
 
hi bro,i may be wrong but if u travell at 110 km/h when the sound came,it could be ur vanos.if i'm not wrong vanos kicks in at speed 110 and above.
 
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