high pitch whistling on the driver side of the engine

[slashnick]

i was driving with the top off recently and heard a fairly quiet, high pitch whistling sound. didnt think much of it until i realized it was comming from the engine.

i got somewhere that i could pop the hood and listened for it. sounds like it is comming from the drivers side of the engine, possibly behind the alternator somewhere. its hard to tell over engine noise and such. it almost sounds like there is a small leak somewhere and air is being forced out and causing a whistling. it is constant, not wavering, and doesnt really seem to get louder as the engine revs. any ideas of why it is?

-matt

 

[Ken]

If you don't have a mechanics stethoscope, you can use a long-handled screwdriver to try and pinpoint the noise origin. A piece of vacuum line also works quite well at isolating the sound.

An alternatior that is about to head south sometimes makes the type of noise you describe, or the belt tensioner, or any pulley, could make a similar noise as well.

_ken

 

[jmccloud]

Locating a noise

Even a 4' long piece of 1/2" or so dia. garden hose (one -clean- end stuck in your ear) will really help locate the source of the sound. Works for tuning side draft carbs too if you're careful with the sensing end location.
The long screwdriver trick is likely better for mechanically sourced noise. The garden hose is good for pressure or vacuum leaks.
Good luck
PS Either way, don't get caught in the rotating parts.

 

[Ken]

Re: Locating a noise

PS Either way, don't get caught in the rotating parts.

Oh yeah! Sometimes it's the simple things that I forget to include in my responses; if you're going to get close to any running engine in order to try to locate a mystery sound or other unusual task, be sure to stay clear of moving parts. And if you have long hair it's best to push it up under a hat or tie it back so that it won't get caught in the machine; that could make you the "Ghost in the Machine." :L

_ken

 

[Bob 89]

I would search around the power brake vacuum boster. Have you noticed any difference in braking?

Bob White

 

[slashnick]

no difference in braking.

i havent checked it with the methods mentioned. but thanks for the ideas and i will definetly check it out soon.

-matt

 

[Eric]

I'm with Ken on this one!

The fact that the sound isn't affected by revs kinda nixxes the TSB on the intake manifold and gasket but here's a thought. Many newer alternators make a noise similar to the one you describe when they are on the verge of death. This happened to my Monte Carlo and I thought it was coming from under my upper plenum, had the stethoscope in there poking around for a week and had determined it was a vac line under the plenum. I bought a new gasket in prep for taking off the plenum and before I got a chance the alternator died. After I replaced the alternator, no more noise.

Good luck!

 

[slashnick]

i got 14.3 volts with everything on. whats normal?

-matt

 

[Ken]

Absolute maximum voltage should not exceed 16v, minimum voltage should not drop below 13v.

Also, for your general information comes this from Dubois Marketing (manufacturers of "The Iceberg Housing"):

As is commonly known in the Alternator Rebuilding business, there appears to be a problem with Delco Remy’s CS-130 alternator. In particular the failure of the rectifier and rear bearing. The current practice in the aftermarket is to come up with a rectifier that can operate under the extreme temperatures generated by the function of the rectifier, converting the AC current into DC current. Little attention has been paid to the fact that the problem with the CS-130 Alternator isn’t in the strength of it’s semiconductors but, the lack of adequate heat dissipation. The number one killer of electronic circuits and bearings is HEAT! If you can keep the heat from building up through proper heat dissipation, you’ve solved the problem.

And this from Ken Smith's Auto Parts Tech Tips:

Many a remanufacturer has heard the complaint from customers, "it was no good out of the box", or "it won't charge". This is especially true for CS-130 (Delco) series alternators if someone forgets to thoroughly check out the battery and all cables/connections between the alternator and battery. The CS-130 alternator's voltage regulator has what is called "Low Voltage" protection. This means that the voltage regulator looks at the state of charge of the vehicle's battery and if that charge is 12 volts or less, it will not allow the alternator to turn on. This protects the alternator from working too hard to charge a low battery. After all, the alternator is not designed to be a battery charger. This is why so many people think they are getting alternators that are bad when in fact there is nothing wrong with them except for the fact that the vehicles battery was discharged, or there was a voltage drop between the battery and alternator due to bad connections or deteriorated cables. So be sure to fully recharge your battery and clean your connections prior to installing a new alternator. Those few minutes of time will save you hours of work down the line.

_ken