Need to do something about squeaky idler on 603 - PeachParts Mercedes-Benz Forum

cmac2012 · #1 09-27-2019, 06:01 PM

I've known this for some time, clearly I'm an idiot for putting it off. This on my '86 SDL. Occurs to me I should probably get a new belt while I'm at it. And a new spring. I don't get how it could be that far off.

Squiggle Dog · #2 09-27-2019, 06:24 PM

When that happened on my roommate's car, it turned out the bolt holding the tensioner had loosened and was ready to fall out.

Mxfrank · #3 09-27-2019, 06:45 PM

The bolt is huge, and usually locktited. What usually happens I are two things: 1 the rocker bearing develops free play and 2 the idler pulley wears conically. I wouldn’t waste money on a spring, but replacing the rocker, idler and shock is good preventive maintenance.

cmac2012 · #4 09-27-2019, 07:55 PM

I just put in a new MB shock. The spring looks old, I've not replaced it, either this time or the previous shock replacement, about a year ago. I put in a new idler a year ago also. I'll get into it tonight.

Diseasel300 · #5 09-27-2019, 09:10 PM

Replace the pivot and the pulley. You don't want to mess with a wrecked radiator (WHEN not IF it lets go) and you certainly don't want to mess with a broken timing cover if it gets all tangled up. Parts are cheap to fix this problem. Stop driving until you fix it. Seriously.

83w126 · #6 09-27-2019, 10:57 PM

Quote:

Originally Posted by Mxfrank

I wouldn’t waste money on a spring,

I would, its definitely not unusual for them to break, and you are at minimum stuck for several days if you don't have a spare, and at worst looking for a new head if it happened where you couldn't immediately pull over.

Mxfrank · #7 09-28-2019, 08:57 AM

The spring isn't causing the misalignment. More than half a million miles of Mercedes driving, and I've never had one fail. YMMV, but I don't think it's a concern. Squirt some oil on it and it will last forever. The tensioner bearing is the usual cause of misalignment, and the only way to fix it is to replace the tensioner.

cmac2012 · #8 09-29-2019, 05:34 AM

This is strange stuff. None of the bolts/nuts are loose. The tensioner and idler are about a year old. It appears that the mount that tensioner is attached to is askew. I'm going to take the radiator out for this one. Need to have a good look. Now I just need to somehow get the fan off. Tried that before w/o luck.

Diseasel300 · #9 09-29-2019, 10:45 AM

If the tensioner pivot failed in only a year it could only be a handful of problems: cheap pivot (buy an Ina), failed tensioner shock (will toast the pivot bearing quick), failed pulley bearing (again, buy Ina), failure to transfer the spacer washer from the old pivot to the new one.

You can remove the tensioner assembly without removing the radiator or the fan. Take the pulley off, then stick an allen bit (I think it's 12mm?) into the pivot bolt and use a wrench to turn it out. It'll be tight, but it'll just clear the fan. Make sure that spacer washer is behind the pivot bearing, if it's missing or not seated it will cause failure of the bearing in the pivot.

cmac2012 · #10 10-01-2019, 07:44 PM

I was incorrect about nuts/bolts not loose. The bolt for the tensioner bearing was loose, that word is loose. Holy chit, came close to disaster. I suspect the issue is the washer you refer to. I don't recall transferring anything. I didn't have the sense to hang onto the old part. Will go to the Mercedes dealer soon to see if on their schematic the space washer has a part number. Might be a relatively common item. Otherwise, I could perhaps fab one.

The part is a Meyle. You can see the name and part no. in the photo. The main reason for the photo is to refer to the shaft. I'm guessing the washer would bear on the larger flat spot below the little bump out shoulder part. I think the part is still plenty good. If I can get the right washer will be much better than the situation I had yesterday.

*EDIT* Just called the dealer, they gave me a part number of A6019901740. I can't find specs for it but I did find a pic that looks like it would behave as I think it would.

Measurements are:

Shaft: .702; 18mm
Shoulder: .787; 20mm
Flat spot: 1.067; 27mm

Cast shoulder of body is .085 (2.2mm) above flat ring.

I took the radiator and fan out. I wanted a good look. Now that I have a handle on some of this it will be easier to do it in future w/o removing it. I think I'll get a special tool with an 8mm Allen wrench on a long arm as seen in this vid. Just being able to easily take the fan out would be nice. Taking the radiator out is a PITA, especially with an auto trans.

https://www.youtube.com/watch?v=UwPf_sSTL7s&t=133s

O'Reilly's has a Gates brand serpentine belt I was thinking of buying. Their rating is decent. I think instead I'll order a Continental and tensioner spring from Pelican. Easy enough to put on later.

Father Of Giants · #11 10-01-2019, 08:41 PM

Get the genuine Mercedes , I went through two INA's in a year.

cmac2012 · #12 10-01-2019, 09:41 PM

There must be something else wrong. This Meyle part was exposed to a hard life and the bearing is just fine on it. The install was bad. Some knucklehead…

Diseasel300 · #13 10-01-2019, 10:00 PM

I ran a Meyle on the SDL. Ran for the whole time I owned it without a problem. Bearing was starting to get sloppy when I pulled it. INA is widely considered to be a better brand, considering it costs about the same as the Meyle and the difficulty of replacing that pivot, I'd shell out for the better part (the 350SD runs an INA). If the bearing is ok on the pivot, the lack of the spacer washer is the likely issue. The washer tends to stick to the pivot and can easily be assumed a tossable part (it isn't).

cmac2012 · #14 10-02-2019, 02:05 AM

I fabbed one I found at NAPA. Slightly too large in diameter. I thought it was too thick so I made it a bit skinnier. Then on install I wondered if should have left it thicker.

All back together, looks great, started it up and after a few minutes heard a small chirp, I'm thinking CRAP! and then I discover the noise is likely this action:

https://youtu.be/bIn7GcGcCl8

Looks like the scuffing it sideways on the idler hurt it worse than I thought. After shutting it off you could see the last rib, the part that's rolling here, starting to separate from the belt.

I might just buy that O'Reilly's Gates brand belt for about $30 after all. I can put it on early tomorrow morning.

cmac2012 · #15 10-03-2019, 02:24 AM

Putting the belt on with the radiator and fan out was pretty easy with the old one, today I had to do it the challenging way. I bought the O'Reilly's offering to put on my car, utterly disregarding the stigma of putting a part from such a store on my fine specimen of German engineering.

Was having trouble moving the belt about so I sought some item I could make into a tool and found the handle for one of those shorty paint rollers, you know, maybe 3 inches long. Whacked the plastic off, ground off the rest, gave it the vice and hammer action and it worked out nicely. Tool visible in vid, pat pending. A lot of R&D went into making this tool.

In addition to the enhanced peace of mind my car sounds nicer now as well. Glad I took care of this even if I put it off for too long.

https://youtu.be/9zI55p3yPHc