Alternator belt squeal

[georgeramos]

I have never gotten the belt NOT to squeal for 10 to 15 seconds after startup since swapping to a 95 amp alternator on my 1608. I have modified, re made and swapped out several different brackets and am quite sure the alignment of the belt is straight. Is it possible that sagging motor mounts can cause an issue. I also have to re weld one of the “fender washers” at the top of the shock mount which broke off last fall after driving with Konis for a season so could that lend itself to a slight mis alignment of the belt?

Thanks all

[18Fiatsandcounting]

There are basically only 2 reasons a belt would squeal: 1) The belt is loose (either through inadequate tightening or glazing/damage of the belt surface or oil or the like on the belt), or 2) one of the pulleys that the belt rides on is driving something with way too much resistance, such as a stuck alternator, water pump, etc.

From your brief description, it sounds to me like the belt isn't tight enough. Or, and this is a long shot, your battery is way dead and your alternator really, really has to work upon startup in a desperate attempt to charge the battery, and this is causing the belt to slip around the alternator pulley.

-Bryan

[DieselSpider]

There is a reason why they went from single to double pulley and then to serpentine multi-rib belts when the higher amperage alternators came out and that is slippage and belt squeal.

Alignment and issues with damaged pullies or old hard belts aside, with a single v-belt of that size its just going to wear out faster and start squealing over time and going to need tightening more often along with going to require more tension on the belt when you tighten it. Motor mounts and shock absorber bolts are not going to impact it unless they cause the belt to rub against something.

[aj81spider]

I can't tell you why it squeals and I'll be following this thread with interest. However you can be comforted in knowing that you are not alone. I have the 95 amp alternator as well (on a 1974 1800). I put it in and the belt squealed - especially right after starting. Sometimes I could goose the accelerator a little and that would make it stop.

Eventually I took it to an "expert" shop who told me the alternator was bad (ironically because I tightened the belt too much trying to get rid of the squeal). I bought another and it also squeals. I measured the alignment and the new alternator was set back a slight bit (between 1/4 and 1/2 inch). I modified the mounts and pushed the alternator forward. To the best of my ability to measure it appears aligned. The squeal got better, but it still squeals when I start the car.

It's not an issue of the belt wearing faster - the belt squeals when brand new (I've tried several different styles and brands of belt).

It's on my list of things to do - except I'm not sure what else to do.

Sorry not to be more help, but I feel better knowing that it's not just me!

[DieselSpider]

A 95 amp alternator when boosting the battery after cranking is going to take more horse power than a single narrow v-belt may provide so its going to slip at times especially when the belt and pulley are still cold.

Sometimes you can overcome this by upgrading to whats called a high capacity belt however they usually are designed to provide maximum grip once they warm up so still may squeal when cold.

Something like this in the correct size for your application might help:
https://shop.advanceautoparts.com/p/gat ... rive+belts

When upgrading alternators from the more common 32 to 50 amp units back in the day to the larger 75+ amp alternators we usually went double pulley whenever possible to prevent slippage when cold or when under heavy electrical loads. The other choice when double pulley was not possible was to add an idler pulley to force the belt to wrap more fully around the alternator pulley however then you needed a longer v-belt with a smooth back that was designed to work with an idler pulley.

Upgrading from a 32 amp to a larger alternator was something I did when putting a snow plow with an electric powered hydraulic pump on a pickup truck since when plowing lots where you would be making a lot of adjustments to the plow angle and needed to raise and lower it a lot you could end up draining the battery low enough that you could not restart the engine after you stopped for gas.

[18Fiatsandcounting]

I know this isn't going to help solve the belt squeal issues, but just for grins: One horsepower is roughly equivalent to 750 watts. So a 95 amp alternator that is operating at maximum capacity is putting out about 1330 watts (95 amps X 14 volts). In other words, generating 95 amps at 14 volts takes between 1.5 and 2 HP, assuming the alternator is 100% efficient at converting mechanical motion into electrical energy. If the alternator is only about half efficient, it could be sucking about 3 HP from the engine. Not hard to imagine the possibility of belt slippage at 1000 rpm or more.

Which leads to the poor man's method of easily adding a couple of HP to an engine: Install a cutout switch to disengage the alternator winding when you need that extra "kick". Not that I'm recommending this, of course...

OK, now back to your regularly scheduled programming.

-Bryan

[ORFORD2004]

You can also use belt dresser in spray can.

[georgeramos]

Thank you for the replies, I have tried belt dressing and have had the car at an electrical shop (a while ago)who said the alternator was working. I am noticing an intermittent starting issue where the starter doesn't turn as if the battery is dead but after a few turns of the key it "catches" and starts like normal. I was thinking starter solenoid but maybe it is related to the alternator after all...

[DieselSpider]

Starter solenoid or ignition switch wearing out. The 10 or so amp load from the solenoid puts a bit of stress on the ignition switch and as it gets weaker it then puts more stress and heat on the solenoid. Many like to put a relay fed off a dedicated fused line from the battery between the ignition switch and the starter to remove that heavy load from the ignition switch.

If you do not have the high capacity belt which is designed to have more grip such as the Gates belt I previously provided the link to then belt dressing may only provide temporary relief if any at all.

This is not a new issue when installing higher capacity alternators on a single v-belt system that was originally designed to support a much smaller alternator. Try the high capacity belt (they are only about $15) and see if that helps reduce the squealing at startup. Also be sure that your not getting any oil slung on the belt from the main or cam bearings or coolant from the radiator, water pump etc.

Some folks who detail their engines with silicone type treatments even it they are using wipes and not sprays may find that those products are migrating to the belts and contributing to having worse slippage and squealing than they would otherwise be experiencing.

[georgeramos]

Thanks Diesel, I will try that belt! I will report back if it changes the situation. I added a fuse panel and relays for the lights but can't recall if I added one for the starter,if not i will do so.

[spider2081]

georgeramos

I don't know what year your car is: If the ignition switch has a 6 cavity connector sometimes the connector is part of the intermittent "start" issues. Spiders with automatic transmissions use a relay between the "start" contacts of the ignition switch and the starter solenoid. It prevented the car from starting when the transmissions was not in "park". I have never seen one of these ignition switches cause the dreaded spider"click" in start. I am a great fan of the relay between the ignition switch and the starter solenoid.
Solenoids have a "pull in" current and a "hold" current. the initial "pull in current is well above the 10 amps mentioned. But using the 10 amps as an example: if the ignition switch "start" contacts have 0.4 ohms resistance and the solenoid draws 10 amps the the voltage developed across the contacts is 4 volts. That leaves 8 volts to pull in the starter solenoid. Many starter solenoids become intermittent below 10 volts. So all the connections and contacts between the battery and the starter solenoid are pretty important.

[18Fiatsandcounting]

Solenoids have a "pull in" current and a "hold" current. the initial "pull in current is well above the 10 amps mentioned. But using the 10 amps as an example: if the ignition switch "start" contacts have 0.4 ohms resistance and the solenoid draws 10 amps the the voltage developed across the contacts is 4 volts.

Yikes, and since power equals the square of the voltage divided by the resistance, that would be (4 x 4) / 0.4 or 40 watts.

40 watts concentrated in the small area of the switch contact points is pretty significant, so you can see why things would head south quickly. Think of putting all the heat from a 40 watt light bulb into a very small area over a period of time.

-Bryan

[georgeramos]

My car is a 71. All this mess started when I went to the "upgrade" 95 amp alternator so I am quite tempted to buy a stock alternator and go back to that. I think that would stop the very loud squeal upon startup. My teenage son cringes every time and looks at me with total disgust

[18Fiatsandcounting]

My teenage son cringes every time and looks at me with total disgust

That's likely to happen no matter what you did! Teenage daughters would just do the eye roll...

-Bryan

[georgeramos]

Has anyone ever just swapped to 2 belt pullies for the 95amp alt, water pump and crankshaft? Are these pullies available, parts from later cars?