Noob with serpentine belt problem - PeachParts Mercedes-Benz Forum

maybe368 · #1 05-23-2016, 02:42 PM

Hi All! Noobie here with a problem on an '86 300 SDL. I did a search but haven't found any real help. I replaced the ac compressor and a new gatorback serpentine belt and now, when the ac is on it squeals and I lose power steering. I can see the pulley on the pump slow down, like it is hard to turn . The pump is a fresh reman unit. I suspect the idler pulley, but there are other tension components that I know nothing about. Before I throw parts at it, what do you guys think? Thanks in advance...Mark

Maxbumpo · #2 05-23-2016, 03:34 PM

I think you have routed the serp. belt wrong. BTDT. If you have the owner's manual, I think it has a picture.

maybe368 · #3 05-23-2016, 04:26 PM

Quote:

Originally Posted by Maxbumpo

I think you have routed the serp. belt wrong. BTDT. If you have the owner's manual, I think it has a picture.

Thanks for the quick answer, but it is on correctly, I just double checked. It wouldn't be my normal luck to have it be that easy. Any other ideas?...Thanks Mark

86-300sdl · #4 05-23-2016, 05:00 PM

Sounds like the belt may be a tad too long. You may also want to check the condition of the idler pulley spring. If its tired it may not give the grip (belt) you need.

In the past I purchased a belt from the dealer that was for a different water pump pulley set up. Initially looked good but I could deflect it downward about 1.5" i.e. push on the belt between the fan & power steering pump pulleys. Dealer said woops...and got the correct belt for me. I also picked up a new shock and spring for the tensioner.

maybe368 · #5 05-23-2016, 05:33 PM

Quote:

Originally Posted by 86-300sdl

Sounds like the belt may be a tad too long. You may also want to check the condition of the idler pulley spring. If its tired it may not give the grip (belt) you need.

In the past I purchased a belt from the dealer that was for a different water pump pulley set up. Initially looked good but I could deflect it downward about 1.5" i.e. push on the belt between the fan & power steering pump pulleys. Dealer said woops...and got the correct belt for me. I also picked up a new shock and spring for the tensioner.

I double checked the belt, it is a Goodyear Gatorback 4060845, which is 84.5". If it is the correct belt, replacing the spring, shock and pulley should correct the tension" I was ready to do that anyway, but I decided to check with the experts first. The car has 345k miles on the clock, so it wouldn't surprise me if it is all worn, thanks...Mark

jay_bob · #6 05-23-2016, 05:56 PM

Important tips for the belt tensioner system:
- be sure to transfer the huge washer over to your new tensioner lever and be careful threading that big bolt, if you strip it then it's timing cover replacement time.
- be sure to get the dust covers for the lever and pulley, they are critical to keeping the hearings from failing from road dirt.

maybe368 · #7 05-23-2016, 06:18 PM

Quote:

Originally Posted by jay_bob

Important tips for the belt tensioner system:
- be sure to transfer the huge washer over to your new tensioner lever and be careful threading that big bolt, if you strip it then it's timing cover replacement time.
- be sure to get the dust covers for the lever and pulley, they are critical to keeping the hearings from failing from road dirt.

Thanks for the advice, I'll be sure to do that. I went ahead and ordered the spring, shock dampener and pulley, I hope that does the trick. I really have only driven this car a couple of miles. I went from ton of things wrong with it to just a couple. It's a sweet car, can't wait to drive it...Mark

BillGrissom · #8 05-25-2016, 12:02 AM

Spray water on the belt and see if the squeal goes away. Look for a Gates youtube about it. If quiets it, usually means pulley misalignment, rather than bad bearings.

compu_85 · #9 05-25-2016, 12:52 PM

Double check your belt routing. I actually made the same mistake when I installed a gatorback belt on my SDL!

Make sure the belt wraps around the bottom of the crank, and just touches the top and bottom of the water pump / fan pulley.

-J

Maxbumpo · #10 05-25-2016, 12:53 PM

If you've still got the old belt, install that and see if the problem clears.

vstech · #11 05-25-2016, 03:44 PM

Quote:

Originally Posted by Maxbumpo

If you've still got the old belt, install that and see if the problem clears.

On some cars, the 91 300D belt is needed... smaller water pump pulley.

maybe368 · #12 05-25-2016, 05:32 PM

Quote:

Originally Posted by vstech

On some cars, the 91 300D belt is needed... smaller water pump pulley.

Interesting, do you happen to know how to tell if the pulley is the smaller one? I also rechecked the belt and it is on right, thanks a million guys...Mark

compu_85 · #13 05-26-2016, 08:22 AM

The chart I posted above has the belt lengths. Your car uses the middle entry... 2145mm.

I believe this is the same as a GM 3800 V6.

-J

Maxbumpo · #14 05-26-2016, 08:53 AM

Another possibility: the new compressor has wrong size pulley?

Jeremy5848 · #15 05-26-2016, 11:45 AM

In addition to the two protective caps, also make sure the seal in the rear of the pivot is present. The seal is plastic and doesn't look like what you'd expect to see after reading the word "seal" but it's part of keeping dirt out of the space between the lever and the pivot bolt, which is just a big plain bearing. See this link and note the caps (#47 and #65) and the seal (#29).

Jeremy