Andy Roe

OK, here's another video from this morning. Set the fan to 0 and temp to full cold. Notice the difference in the high pitch noise when I disconnect the rear blower and that the noise changes with the change in engine revs. I can hear it in the car too.


I've booked it in with the shop next week for them to find out what the problem is!

Harry Apps

May be related to the electrical load on the alternator when powering the fan. Suggest you try the same tests but also use the headlights (on/off) to increase the load to see if the tone varies.

Andy Roe

Yes, this is what I'm wondering too and that it's possibly a lazy alternator. I'll try with the headlights and report back.

HalV

These are my thoughts, too! Let us know what they find.

dannyg

Hi Guys,

Has there been an update to this?

I have a problem where the air coming from the vents seems to vary based on my engine speed!

Thanks
Dan

Andy Roe

My mechanic couldn't see anything wrong with it in the end. Before it started I had changed the complete alt/pulley assembly and he thinks it's because it's a mix of 993 and 964 parts that is causing the whine. I'm not 100% sure I agree with him though.

Dan - Does your car have the rear blower assembly removed? I wonder if that could cause the symptoms you mention, but it would maybe only do that if you wanted hot air. Does it also do it when you have the temp on min?

dannyg

Hi, I don't believe that it had anything removed as it's a low mileage road car.
I am unsure of whether it changes on different temperature settings as I drive the car very little and have not had change to play around with it much!

Thanks
D

Andy Roe

Time for an update on this. It's got a lot worse - especially so just have starting the car when the engine is cold. Time to take it back to the mechanic..

FeralComprehension

Apologies in advance for the obvious suggestion but have you all tried to find it with a mechanic's stethoscope? It definitely sounds mechanical vs. electrical to me (based on the most recent video) so I'd probe around all the usual suspects- alternator, engine cooling fan housing, PS pump, ac clutch, distributor...

Agree it's a worrying noise!

Goughary

I wouldn't take that to a mechanic just yet Andy. You have the tools to take the belts off. So take the belts off and start the car. See if the whine is gone. Then check to make sure the fan isn't rubbing anything. And the belt tension sensor isn't dragging on a belt. Then if all is well and when you turn the fan by hand, you don't noticeably feel a bad bearing. Put the fan and alternator belts back on. Leave the ac belt off. Start the car. See if the noise is back. If yes, bad bearing likely in the alternator and if no, add the ac belt. If it comes back then it's your bearing in the ac compressor clutch. If that turns out to be the case, take the clutch off, press out the old bearing and press in a new one. Don't forget to peen it in place as per original and you are all set.

All of that can be done without a tech and without spending much, if anything at all.

Also look down under the crank pulley for something dragging on a belt.

Goughary

Also. Pull the cover off the top of the fan housing and listen to the back of your alternator. From the earlier videos, sounded to me like the noise was still there when you unplugged the heater motor, but that with the heater motor on, the sound was more able to come through that side...leading me to believe the rear of yur alternator may be the prob.

I would do some exploration. Then if it's the alternator I would pull the voltage regulator and make sure there isn't missing brush in there...if one of the brushes disintegrated, you would get a whine like this...out of the back of the alternator.

Anyway, all this can be done w basic tools...

If flights get cheeper, I'll fly over and give you a hand...been a long time since I've had a good bolognese...

Andy Roe

Thanks for the feedback guys. I'm toying with the idea of taking it apart tomorrow. I had the alternator and fan assembly replaced in it's entireity after the last alternator shaft broke which I why I'm thinking of just leaving it with the guys who did that work. It doesn't sound like it's coming from the air con compressor but I could be wrong though. The odd thing is whilst the whine is pretty much always there, this new noise seems to go once the car has warmed up - maybe the bearings expand a bit and stop making a the noise? I also get the odd squeak when just starting it too - not a belt slipping squeak, but it's there sometimes for a split second or so if I blip the throttle

Andy Roe

OK, I did some work on the car this morning.

Firstly, I took off the aircon belt and both the whine and mechanical noise was still there. So all good with that.

Secondly, I took off the alternator belt and left the fan belt in place. No mechanical noise and no whine.

Thirdly, replaced the alternator belt and whine returned (good), but also no mechanical noise.

I think my next step will be to replace the voltage regulator as Robert suggests as I agree that is likely the culprit for the whine as I also have the ABS light stay on until the revs go over 2K rpm sometimes after starting which would also indicate that. I'll order a new one and try to replace that next weekend.

I'm a bit stumped for the mechanical noise although I'm inclined to think it's the alternator. When I have a bit more time (kids allowing!) I'm going to take off the alternator belt and try several cold starts over a few days to see if the mechanical noise comes back. If it doesn't then I think that will show it's the alternator. If it does, I'll try the same but also with the fan belt removed.

Could a failed bush in the voltage regulator also produce the mechanical noise if it some how got out of place? Just wondering if the 2 could be connected.

Goughary

Andy, how much does a voltage regulator cost in Italy? They used to be inexpensive here and have gotten to be pretty costly. Still cheaper than a rebuilt unit. But when I needed one, I just went with a rebuilt alternator for 250 dollars with mine as a core. I seem to remember not so long ago the voltage regulator alone was 50...which isn't the case here anymore.

Andy Roe

The regulator is about 70€, so not exactly cheap but not bad. I think a new core is are around 500€ now. I had the alternator replaced in 2013 with the hub and fan (the shaft sheared and caused the fan to disintegrate) but my invoice doesn't show the regulator as a separate part so its possible they transfered the one off of my old alternator onto the new core.