My 82 300SD has been making belt noises upon acceleration in the mornings or when it has been sitting for a while, and also decided to "scream" for a bit in the Tim Horton's drivethrough two days ago (kind of embarrasing for the wife).

I looked at my belts to look for one needing replacement, but really had no idea what to look for, or which belt to look at.

Some starting points would be good - thanks.

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79 300SD - $50 out of pocket purchase
03 Dodge Ram 3500 CTD
2003 VW Jetta TDI

Has the AC been converted to 134? I found that caused the AC belt to squeal on a Buick I used to own. Pressures were higher putting a greater load on the compressor and belt.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Check for any loose belt, try to inspect inside of all, you may notice a glaze somewhere. When I had an occasional shreeek!, I replaced the alternator, problem solved, the bearing finally gave up.

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83 SD

84 CD

The AC has been "changed to the new fluid", as the PO told me.

The belts looked fine to me for what I could see....the thing for me is that it seems to do it only on first acceleration, then it's fine.

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79 300SD - $50 out of pocket purchase
03 Dodge Ram 3500 CTD
2003 VW Jetta TDI

Take a wax candle and carefully touch both edges of a single moving belt. Then drive it for a couple of days and see if the noise disappears.

If not, do a second belt. Same test.

If not, the third belt is the likely culprit.

The a/c belt should be easy to condemn or not. If it only makes the noise with the compressor engaged, then you've found the problem.

Otherwise, my money is on the PS belt.

When you change them, get the Continentals..........which are metric and are designed for the vehicle.

Thanks, I'll try that.

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79 300SD - $50 out of pocket purchase
03 Dodge Ram 3500 CTD
2003 VW Jetta TDI

on the 82, the alternator belts are notorious for this exact thing. you have to have a matched set of perfect condition belts or they will squeak, no way to tighten them enough. however, since you have to pull all the other belts off to change them, thoroughly inspect the others and just change them all... that is a guaranteed way to fix a belt squeak.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Whcih leads me to a question (not trying to hyjack here): What, other than simply a backup if the first one breaks, is the purpose of having 2 belts on the alternator?

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1989 300E 144K

I assume they were intended to carry more load without the belts having to be very tight. BTW, the only time mine have ever made noise was once when they were very loose. Of course, I replace mine anytime they look like they are thinking about beginning to wear. Make sure you get the proper metric belts (this site, the dealer, etc.) the McParts store belts are not really the correct size.

Just push down on it with your finger, they are only supposed to deflect a bit.

These cars have double belts so they have to be pretty lose to make noise. Well unless its the power steering or AC, but those are pretty odvious. PS would make noise when you turned the wheel, AC when you kicked on the compressor.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Craig is right. Two pulleys increase the amount of surface area between the pully and the belts. Diesel's, such as are MB's, pull a lot of current out of the battery upon start up. There is a huge current drain from the glow plugs and then because our compression ratio is higher, the starter pulls more current. That is also why we have bigger batteries then the gassers. Therefore the alternator has a much bigger load in recharging the battery after start up.

TimK

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EPA 609 & 608 HVAC Certified
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83' 300D Turbo - 300K + Miles
00' 1.9L TDI Beetle
85' 6.5L Turbo, GV-OD, GMC Suburban,
67' 2.5L Diesel NA - Land Rover Series IIA

Here's what you do if it's so cold your diesel fuel gels. Smear some on some toast and stay inside until it warms up outside.

Then why do the non-turbo's have only one?

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

So if I push down on them and they have lots of tension, and otherwise look fine, they're probably good? Especially if it is an intermittent thing?

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79 300SD - $50 out of pocket purchase
03 Dodge Ram 3500 CTD
2003 VW Jetta TDI

Did they get wet? If you drive through a puddle or something they will make noise.


Belts should be silent, if they squeal something isn't right.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Good question, did the NAs originally have smaller alternators? Maybe it was just an "upgrade" on the later cars?