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Hi, I have a 68 Olds Cutlass s with the 350 4 barrel. Recently the car has developed a buzzing noise associated with the charging system, I think. I replaced my voltage regulator and it helped a little but now the buzz begins below 30mph and stops under 10 mph. It goes away under acceleration. Im stumped. Any ideas? The noise seems to be coming from the v regulator itself.
Well if all else fails and it only happens at speed, you can get the car to 30 on a 2 post or single post lift (still using a stethoscope to find the source of the noise). That is how dealerships isolate and fix harmonic driveline vibrations that can't otherwise be isolated through a road test. It should have been obvious but I will ask anyway: The car does not have a U15 safety sentinal speedometer does it?
Last edited by Loaded68W34; Mar 18, 2022 at 02:52 PM.
Well if all else fails and it only happens at speed, you can get the car to 30 on a 2 post or single post lift (still using a stethoscope to find the source of the noise). That is how dealerships isolate and fix harmonic driveline vibrations that can't otherwise be isolated through a road test. It should have been obvious but I will ask anyway: The car does not have a U15 safety sentinal speedometer does it?
Just to add: When this happe3ns, the GEN light flickers on and its intensity is proportional to the sound of the buzzer, so I am sure it is a charging issue.
What is the voltage on the battery terminals with the engine running @ idle with no electrical equipment running in the car - all lights off, radio off, etc.? You should be delivering (reading) a voltage at the battery terminals of >14.0 volts, optimally ~14.6V and it should be nearly steady with very, very limited wavering.
There are no mice, cats and critters living in or under the dash - so, we can most likely rule out animals. The measured voltage is fine. Suggestion/Question. If, by chance, you've done any electrical upgrades, improvements, moving wires about etc. under the dash, on the firewall, etc. check your electrical connections for plugs which are not soundly connected. There are no "buzzers" located in the dash or under the dash. The only "buzzer" is the door buzzer if you open the driver door w/ the key in the IGN (I think the '68 has the door buzzer feature). I'd check electrical connections first.
BTW, and I'm assuming this to be correct since you did not state otherwise, the ONLY light which flickers on & whose intensity is proportional to the sound of the buzzer is the GEN light - no other lights manifest this issue? There are the peculiar occasions when a lamp begins to falter you "may" begin to hear it slowly begin to reach its death &/or the lamp contact point has become corroded. There's a very slight off-chance the ground terminal for the instruments is not secured tightly, but I'd suspect you'd see all the instruments lamps demonstrate the same issue. It does appear isolated to the GEN lamp circuit apparently.
Clean your ground cables - remove the wires, clean each of the wire terminals/ends and the metal at each point of attachment. Solid grounds are extremely important and are replete with electrical issues. It can't be stated enough, if no one has cleaned the grounds on a 50 year vehicle, now is the time to clean them.
Does it constantly buzz or does it ONLY buzz as per your previous statements regarding begins below 30mph and stops under 10 mph? I'm suspecting it's buzzing continuously.
What is the Part Number of the VR you currently have installed? Have you validated the Part Number is the correct Part Number employing usual sources of information (as opposed to taking the word of a automotive parts store employee who may have provided an incorrect VR Part Number)?
Rock Auto is most generally correct on Part Numbers and applications. Here is a listing of VR's for your vehicle. Validate cross references for your currently installed VR.
Sounds like you have a mechanical voltage regulator as those have contact points that open and close as part of the regulation action. So maybe there is an issue with the alternator, and that is causing the points to chatter?
There is a troubleshooting procedure for verifying voltage regulator and alternator operation in many repair manuals, such as the CSM.
Sounds like you have a mechanical voltage regulator as those have contact points that open and close as part of the regulation action. So maybe there is an issue with the alternator, and that is causing the points to chatter?
I was (next) suspecting same. It "would" be a benefit to validate the Part Number of the currently installed VR to further elucidate if the Alt. is compatible with the VR, especially if the Alt. is an aftermarket hybrid or some unknown frankenstonian lineage.
Have you ensured that the locations on the firewall where the voltage regulator bolts up are clean and bright metal before you bolt it in place? Poor grounds are frequently the source of buzzing in a mechanical regulator. Also, consider getting an electronic regulator like Wells VR715. If appearance is important, you can swap the cover to one with the Delco logo stamped into it.
X 2 on the Solid State VR, clean grounds, good overall system connections, and a healthy alternator.
I had a problem on my 68 years ago where the gen light would stay on after turning the ignition off. It would eventually go out minutes later and you could hear a twang from the mechanical VR. Not a comforting situation.
I could force it to release by applying a load such as the headlights or just tapping the starter. You could hear the Mechanical VR let go with a twang and disconnect, gen light off.
Occasionally I would get system light flicker and the buzzing sound at idle.
This was a time when good Delco parts were drying up and the chineasium junk was beginning to flood the market. Chineasium was the only thing available at least from new stock at that time. I went through 3 new VRs same results.
Disgusted and needing to solve this, I found an old-school Alternator/Generator shop. The guy tested my alternator and all 4 VRs as a system, the original and 3 new. He concluded all 4 VRs were weak/erratic. He mentioned the quality was **** compared to Delco of the past. He showed me how he tested them on an O-scope. When he hooked up the SS VR the sine wave was 100% smooth no chop throughout the alternator rpm range. Charge voltage was steady. There is a dampening circuit in the SS VR not found in the mechanical VRs
I installed that SS VR, gotta be close to 25-30 years ago. The problem never recurred.
