Alternator squeal after engine start

[burn_your_money]

It's true, AC is the first thing to go in the scrap pile. However, I had belt problems then I did the voltage drop test and fixed the problems. If you saw how loose and crappy looking my belt was you would be amazed that it didn't squeal.

At any rate, a voltage drop test is easy to do and is good for your car.

[92EcoDiesel Jetta]

It's true, AC is the first thing to go in the scrap pile. However, I had belt problems then I did the voltage drop test and fixed the problems. If you saw how loose and crappy looking my belt was you would be amazed that it didn't squeal.

At any rate, a voltage drop test is easy to do and is good for your car.

I am not familiar with an AC less 1.6 diesel. I am guessing the alternator tensioner design on yours is different than mine. The problem with the tensioner design on a 1.6 diesel with AC is that there is less and less belt to pulley contact with more and more tensioner adjustment, exacerbating the problem. Changing the belt to one with more grip and less tendency to stretch (a lawnmower belt) fixed the squeal, which was due to the OEM spec belt not able to handle the load placed on it. I don't think I have bad wiring. I know what a voltage drop test is and will check my power wiring out for the sake of it

[92EcoDiesel Jetta]

Thinking more about your theory that voltage drop is causing my alternator belt to squeal. The only way I see that can be is if the voltage drop is between the battery terminal and the battery, which would place the glow plug load more so on the alternator than on the battery, increasing the alternator's work load. My battery terminal and battery post is nice and clean, so I don't think that is the problem.

[burn_your_money]

It could also be your alternator to engine block connection, the engine ground wires or the positive wires from the alternator to the battery.

I'm not saying it definitely is your only problem, but it could be a contributing factor and since many others have this problem, it may help them out.

I'm familiar with the poor design that VW did on the AC systems. However I can't see the belts squealing on the lot way back in the day.

[DieselBalz]

Is there a part number for this lawn mower belt?

[92EcoDiesel Jetta]

It could also be your alternator to engine block connection, the engine ground wires or the positive wires from the alternator to the battery.

I'm not saying it definitely is your only problem, but it could be a contributing factor and since many others have this problem, it may help them out.

I'm familiar with the poor design that VW did on the AC systems. However I can't see the belts squealing on the lot way back in the day.

Way back in the day? You mean when the car was new off the lot? I suspect belts were of better quality/ materials and a different design back then. I think they were regular belts with no teeth or cogs for cooling, which means more surface area contact, a better grip and they'd last longer. I think those teeth or cogs is a way to use less rubber in the belt (cheaper to manufacture) and does not do anything really useful. Nowadays manufacturers don't care about quality, only the bottom $ line.
I can't believe the brand new Goodyear Gatorback alt belt stretched out and became useless in a little over 3 weeks.
So far the lawnmower belt has not needed an adjustment and has not squealed at all with approx 300 miles on them.
Dieselbalz, I listed the p/n of the lawnmower belt I used earlier.

[R.O.R-2.0]

Is there a part number for this lawn mower belt?

the part number is for an a/c equipped vehicle.. FWIW..

us without A/C, were gonna have to find out what belt fits on our own.

[DieselBalz]

Missed that Gates 6827, for those scoring at home.

[92EcoDiesel Jetta]

Updating this thread with new info. With a photo tach, I measured the RPM of the Gates 6827 lawnmower alternator belt (alt with AC) and at idle it is 708 RPM. Since my idle is around 1000 rpm (yes a little on the high side), so, at 65 mph, which is around 3000 RPM in 5th, the lawnmower belt is at 2124 RPM. According to a lawnmower repair place, some belted lawnmower engines run at 3500 rpm, and I am running it at way below that so the belt may be fine in the long run. So far I have not had to adjust the belt tension and it has not squealed at all.

[R.O.R-2.0]

Updating this thread with new info. With a photo tach, I measured the RPM of the Gates 6827 lawnmower alternator belt (alt with AC) and at idle it is 708 RPM. Since my idle is around 1000 rpm (yes a little on the high side), so, at 65 mph, which is around 3000 RPM in 5th, the lawnmower belt is at 2124 RPM. According to a lawnmower repair place, some belted lawnmower engines run at 3500 rpm, and I am running it at way below that so the belt may be fine in the long run. So far I have not had to adjust the belt tension and it has not squealed at all.

will the lawnmower belts fly apart if you turn them too many RPMs?

my diesel regularly sees 5000+ rpms..

[92EcoDiesel Jetta]

Updating this thread with new info. With a photo tach, I measured the RPM of the Gates 6827 lawnmower alternator belt (alt with AC) and at idle it is 708 RPM. Since my idle is around 1000 rpm (yes a little on the high side), so, at 65 mph, which is around 3000 RPM in 5th, the lawnmower belt is at 2124 RPM. According to a lawnmower repair place, some belted lawnmower engines run at 3500 rpm, and I am running it at way below that so the belt may be fine in the long run. So far I have not had to adjust the belt tension and it has not squealed at all.

will the lawnmower belts fly apart if you turn them too many RPMs?

my diesel regularly sees 5000+ rpms..

I will be calling Gates and will ask that question amonst others.

[larry104]

FYI. I learned (from talking to engineers at belt manufacturers) that automotive V-belts are not designed to have a roller pressed against the flat part of the belt as you are doing, whereas the lawnmower belts are. If you have no problems, then great. If you do, you may want to consider going to a lawnmower belt.

Well, so far I'm proving the belt engineers dead wrong. I've got over 7K miles on this setup and no slip. The Dayco automotive belt looks like the day I installed it. FWIW, I tried a wider automotive belt with the stock tensioner. The belt kept slipping and failed in a couple of weeks.