Chirping Sound in engine

[Tyeo]

For some time now, I have detected a "chirping" sound in my engine - like a little bird. It doesn't affect the performance or anything but it's very annoying. At first, I thought it was the fan blades coming into contact with the fan housing but I got those parts changed and made sure that there was a bit of clearance. As the noise only appears when the engine is running, it obviously comes from one of the "pulleys" or belts. I can't seem to pin-point where it's coming from and I'm sure a good squirt of WD-40 will do the trick. Any suggestions are welcomed as the noise is driving me nuts !!!

[curiousone940]

Just a shot in the dark,,,,I'd take a look at the alternator bearings myself

[Meka]

I had the same noise. At first I thought it was the alternator or a pulley. It turned out to be the distributer.

[Tyeo]

Thanks guys for the feeback but why would the distributor be making that chirping sound and what did you do to eradicate the noise ? I'm hoping it won't be too involved or costly to rectify the problem.

[sammyg2]

Engine? Intake?
Lots O'blanks to fill in, but I do know that if you have carburetors they can make that noise if not synced just right, BTDT.

If not from the carbs, take a bar of hand soap (not lava or any kind with abrasives in it) and carefully touch it to the tapered sides of the belt where it wedges into the pulleys. Use whatever tool is required to be safe, obviously make darn sure that you take the necessary precautions to keep your hands, clothing, etc out of the rotating parts.
DO NOT use WD-40 on the belt unless you have a spare belt ready to install. WD-40 sux.

The soap will act like a belt dressing and will not damage the rubber. Old garage trick I learned many moons ago.
I discussed this with an application engineer from Gates rubber company about 15 years ago, he laughed and asked how I knew their trade secret. He also stated strongly that we should never, ever use belt dressing or petroleum based lubricants or solvents on the belts even though it would be good for his business because they would sell more belts if everyone did that.
The soap will eliminate the noise right away if the noise is coming from the belt. It may come back later, but that would mean you need a new belt. At least you would know what needs to be fixed.

Also, when the engine off, look at the pulleys. They should be shiny on the sides, but not in the bottom of the grooves. If the belt is riding in the bottom of the groove instead of on the sides, either the belt is really worn out, or the wrong size, or the pulley is worn.
The sides of the pulley should be straight (not parallel, just straight), if they are cupped at all that indicates unaceptable wear from a slipping belt and it should be replaced. In otherwords, the sides of the groove should look like a V, not a U.

You can prolly tell I spent way too much time as a young reliability engineer trying to solve some PITA V-belt issues at a refinery.
Ended up changing most of htem to Gates poly-chain ribbed belts, the electricity savings paid for the design change in two years, and the maintenance savings was more than double that. Oops, got sidetracked again.

[Beethoven]

Difficult to diagnose without knowing what kind of car you drive. My money would be on the alternator.

[pa911]

Fan blade touching housing?

[Tyeo]

Hey Sammyg2,

I suspect that you may have hit the nail on the head and will try your suggestion. The reason I say this is because my mechanic (in trying to eradicate the noise) sprayed some WD-40 on one of the belts (I know, I know...WD-40 sucks!) and the noise did disappear but came back subsequently. Another thing, the chirping noise only "appears" after the car is driven for a while - it doesn't happen on fresh start-ups. BTW, it's a 1988 3.2 Carrera - sorry for missing that out. The thing is - my belts look in pretty good condition - they're not that old.

[Zeke]

Originally posted by pa911
Fan blade touching housing?

[Tyeo]

No, it's not the fan blade touching the housing - the first thing I discounted. Any other ideas ?

[coloradoporsche]

Had the same problem. Replaced alternator thinking it was the bearing. Turned out to be the distributor. Oiled the distributor and never heard it again.

[Tyeo]

Sorry for my ignorance but how does one "oil the distributor" ? Can I just remove the cap and (easy on the rebuke) spray some WD-40 ?

[gost]

This thread might answer your question. distributor lube...
Good luck

By the way the link is page 2 of the thread, check out page one for the full scoop!

[ianc]

I had a chirp like this, but it actually turned out to be that the fan belt was too loose and it was slipping. Tightened it and haven't heard it since.

ianc

[Sameer]

Heard the same noise, changed the compressor and the bird flew away to another Porsche

[Tyeo]

OK. I'm down to a few possibilities :-
1. A belt that might do with some soapin' ;
2. worn pulley/s
3. oiling of distributor ;
3. changing aircon compressor.

I like the last option the least as it appears to be the most expensive. Besides, my aircon compressor ain't that old either. Will give feedback after I try the soap and oiling of distributor. Cheers and thanks for all the responses.

[4to8m8]

I have the same little bird hiding somewhere in my motor. I suspect the alt and belt since they were recently taken apart by yours truly. Funny this thread has just materialized as I just noticed the chirping yesterday.

[Tyeo]

Hi Reverend Ray - Annoying isn't it ? Do let me know if and when you have identified the culprit and eradicated the problem. Thanks.

[4to8m8]

Tyeo - Rule out the Compressor. My belt is not attached and our chirp sounds the same. Will let you know if I isolate anything.

[kach22i]

Pulled head stud?