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-   Porsche 911 Technical Forum (http://forums.pelicanparts.com/porsche-911-technical-forum/)
-   -   Engine "Woo Woo" Noise (http://forums.pelicanparts.com/porsche-911-technical-forum/862694-engine-woo-woo-noise.html)

frannyB 04-30-2015 11:27 AM
Can you disconnect your fan belt and run - just for a moment - to eliminate the fan and alternator?

Franny

DRACO A5OG 04-30-2015 11:42 AM
Remove the fan belt and check. Do not run for a long time, just enough for a listen.

I have my buddy's Good Dizzy, will be checking against my rebuild. His is tight and 0.10MM play only and the proper drag upon spinning.

NICE 69 S 04-30-2015 11:49 AM
MY VW made that sound when it sucked a piece of paper into the fan. If the sound goes away with the fan belt removed, look for something that may have gotten sucked up by the fan and is under the shroud.
Bob B

OsoMoore 04-30-2015 11:52 AM
Quote:
Originally Posted by NICE 69 S (Post 8602406)
MY VW made that sound when it sucked a piece of paper into the fan. If the sound goes away with the fan belt removed, look for something that may have gotten sucked up by the fan and is under the shroud.
Bob B
I'll try the fan belt when I get home tonight (unless raining).

McLovin 04-30-2015 11:56 AM
Sounds like "wooo wooo"?

Might it be this?

<iframe width="420" height="315" src="https://www.youtube.com/embed/JZD-ADArwXo" frameborder="0" allowfullscreen></iframe>

tirwin 04-30-2015 02:02 PM
Hey, OsoMoore,

Did the dizzy fix your arcing?

I must've missed the update.

Porsche 2 04-30-2015 03:28 PM
Long shot, Belt tension?

OsoMoore 05-01-2015 06:06 AM
Quote:
Originally Posted by tirwin (Post 8602607)
Hey, OsoMoore,

Did the dizzy fix your arcing?

I must've missed the update.
Yes tirwin, some combination of my dizzy cleanup, green wire fix, and new coil. Details here! http://forums.pelicanparts.com/porsche-911-technical-forum/856863-bouncing-tach-when-cold-zap-noises-7.html#post8595884
I really appreciate the input from all y'all on that challenge. (Drat, too much time spent in Texas.)


So I was going to pull the belt last night, but the wife wanted to go for a drive and a movie, and who am I to say no? Hopefully Saturday morning I will have time to wash the car and check this too. I think I also need to up the idle a little bit. She's at about 700 and sometimes coughs because of it.

nene 05-01-2015 06:44 AM
My 86 makes the sam sound and always wondered what it was. I will try removing the belt and report with my findinds.

gliding_serpent 05-01-2015 07:49 AM
Damn, you beat me to it!!!


Quote:
Sounds like "wooo wooo"?<br>
<br>
Might it be this?<br>
<br>
<iframe width="420" height="315" src="https://www.youtube.com/embed/JZD-ADArwXo" frameborder="0" allowfullscreen=""></iframe>

Jose_JGC 05-01-2015 12:29 PM
Another vote for the fan belt too tight here. Or a faulty alternator bearing.
Last time I installed my alternator I had the belt a bit too tight and there was a Woo Woo sound like yours.
Jose

wwest 05-16-2015 09:37 AM
Quote:
Originally Posted by OsoMoore (Post 8596988)
My distributor is back together and engine is running great (thanks wwest, timmy2, tirwin, and the rest of the PP ignition geniuses).

However there is an odd noise that has been emanating from the engine throughout the adventure, and has not dissipated along with the arcing fix. It is a hollow "woo woo woo" noise, similar to the sound of blowing across the top of a glass soda bottle. It only appears once the engine has warmed up. Sometimes it stops, but soon returns. With the engine lid closed, you cannot hear it very well unless you are listening for it.

Maybe a vacuum leak of some kind?

<iframe width="560" height="315" src="https://www.youtube.com/embed/8vEMytRoQOI" frameborder="0" allowfullscreen></iframe>
Playing forward..

There does seem to be a failing bearing noise in he audio background..

Avanti 05-16-2015 10:17 AM
I'm with CCM911, could be alternator related, bearings and even the diodes working (or not) can make similar noises.

Run the engine with the fan belt removed to see if the noise goes away. Also with the engine off, spin the fan with one hand and your other on the housing to feel for a rough bearing.

OsoMoore 05-24-2015 05:20 AM
Whilst awaiting a CDI swap, I have taken out the alternator. Spinning on a table, there are no bad noises and things seem OK. I'm planning to put it back in and adjust the belt when I get the new CDI box.

OsoMoore 05-25-2015 10:39 AM
Change of heart! Took apart the alternator partly. Removed the long bolts but haven't gotten the rest off yet (going shopping with the wife for her birthday now).

One of the brushes is significantly shorter. I'll post a picture. Does anyone sell an alternator rebuild kit, or a new brush kit? Doesn't seem that hard to work on seeing as it is just a clean-refresh effort and nothing is actually broken.

eastbay 05-25-2015 10:47 AM
I used these guys to source all the parts for my alternator rebuild

- Alternator & Starter Parts Wholesale

DRACO A5OG 05-25-2015 11:57 AM
I think the hard part is soldering/welding the brushes on with hot enough soldering tool.

wwest 05-25-2015 12:27 PM
You can purchase slip ring brush/holder assembly, no soldering required.

But given the HEAT level of the pulley you noted earlier I would be very suspicious of the front bearing. Where you able to find the # of years/miles your alternator has been in service?

Complete rebuild kits, new slip rings, brushes, regulator, bearings, are available for under $40.

wwest 05-25-2015 12:34 PM
And be sure and look closely, examine, the stator wiring support/insulators.

OsoMoore 05-26-2015 05:09 AM
Quote:
Originally Posted by wwest (Post 8636931)
You can purchase slip ring brush/holder assembly, no soldering required.

But given the HEAT level of the pulley you noted earlier I would be very suspicious of the front bearing. Where you able to find the # of years/miles your alternator has been in service?

Complete rebuild kits, new slip rings, brushes, regulator, bearings, are available for under $40.
Ok, I'll see if I can nab such a kit. Would you happen to have a link? I'll start looking around. Right now I ran into an annoying issue during dis-assembly. I can't quite get a wrench onto this stupid bolt:
http://forums.pelicanparts.com/uploa...1432645644.jpg

Also, here is a picture of the current length of my brushes. The long one is 1/4 inch, the short one is 1/8 of an inch.
http://forums.pelicanparts.com/uploa...1432645682.jpg

I can check my records when i get home. It is a Valero alternator that has somewhere between 40 and 60K on it, assuming it at least replaced during the rebuild 15 years ago. I'll have to pull out the Big Book to be sure.

I see lots of kits here: Bosch - Alternator & Starter Parts Wholesale
But I don't know which one is right.


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