belt service

[dds28]

Hi everyone,

I am about to replace the serpentine belt. Any recommended replacement of other parts while I am replacing the belt? Idler, tensioner,..? First time doing this myself. Do I need to remove the fan to replace the belt? I just finished all the replacements of the cam oiler tubes to the older metal ones, valve cover gaskets, timing chain guides, and spark plug wires. Thanks to Gerry, Dave, and other member's instructions on their posts of the related procedures.

David

 

[gsxr]

David, what year is your car? 1992 has a manual tensioner with 8-rib belt, 1993-up has automatic tensioner with 6-rib belt. Very different procedure for each.

No need to remove the fan either way though!

 

[gerryvz]

Hi everyone,

I am about to replace the serpentine belt. Any recommended replacement of other parts while I am replacing the belt? Idler, tensioner,..? First time doing this myself. Do I need to remove the fan to replace the belt? I just finished all the replacements of the cam oiler tubes to the older metal ones, valve cover gaskets, timing chain guides, and spark plug wires. Thanks to Gerry, Dave, and other member's instructions on their posts of the related procedures.

David

I only have direct experience with the later cars (1993 and up), with the modified and better tensioner. You can easily remove the belt without removing the fan, just by activating the tensioner to remove the tension on the belt. This will give you enough slack where you can unhook it from one of the pulleys, and then remove it from the engine.

HOW-TO: Replacing M119 Serpentine Belt (with automatic tensioner) | "HOW-TO" Tutorial Articles

A few weeks ago, I noticed while working under-hood on my E500, that my serpentine belt had a fair number of cracks throughout the rubber ribs that contact the pulleys on the front of the engine. I was a bit surprised, having just replaced this same belt exactly two years ago, but the Texas...

www.500eboard.co

I actually just ordered a spare tensioner, and it will be here tomorrow. If yours has not failed, I would re-use it, but if you are a long-term owner I would consider having a spare in your parts stock. Or just order one and replace it. I think I paid around $95 for it, discounted, from my local MB dealership.

For the idler, once the belt is removed I would spin it and see if there is any noise from the bearing/pulley, or if it is OK. If OK, and no noise, then I would leave it. If you hear the "whoosh" of bad bearings, replace it. Also give it a visual inspection, as they can become cracked from stress. If all looks and sounds OK, then you are probably OK to keep using it.

 

[gsxr]

Ditto what Gerry said. As FYI on the automatic tensioners, only buy OE/Genuine from the dealer for both tensioner and pulley. Aftermarket items do not appear to be OEM and I've even seen a Trucktec pulley in an INA box (!). Not worth the risk.

For the 1992 manual tensioner, OE is also recommended, along with setting the adjustment on the 'loose' side to avoid stressing the rubber bushing.

 

[dds28]

Dave,

I have a 95 e420. Sorry forgot to mention.

 

[Joncf]

I actually replaced my tensioner last month, as I saw an extremely slight oscillation of tension at idle when looking at it. I have the later style one. When removing the pulley nut.. I’ve found that it’s easiest using an offset box wrench to break it loose, WHILE holding the end of the shaft in place with the appropriate E-10 Torx socket inserted through it. This way, you won’t have to fight the tensioner rotating left as you loosen the nut. After, when tightening down the nut with the new tensioner installed, there is no issue since the tensioner has no movement in that direction. There is also a bushing around the uppermost mounting bolt, which is the longer bolt of the three holding it on.

I suppose you could alternatively remove the tensioner with the pulley still installed, and then use an impact to “zip” the nut off.

These tensioners really do last a long time, as mine was original. It’s a nice design, in that you could remove JUST the pulley in about two minutes to press in new bearings, without replacing the entire tensioner if need be. This isn’t the case on the later M112/M113 engines, where the pulley isn’t removable.

 

[gerryvz]

Here are some views of the late-model (1993 and up) belt tensioner. I just picked it up today from MB Annapolis.

Such a superior design as compared to the earlier ones.

 

[gsxr]

Nice! Do you know what company manufactures this? I don't recognize the logo:

 

[Joncf]

Nice! Do you know what company manufactures this? I don't recognize the logo:

View attachment 157671

Although I don’t know the answer to that question, that’s an old stock part (2001). I’m fairly certain the manufacturer is different for the current ones being produced. The new ones don’t have that symbol, and the cast writing is in a different font, along with other very minor machining differences. I could be wrong.. that company just might not mark their logo on their products anymore.. so it’s difficult to say.

Interestingly, and unsurprisingly to me, the current Febi Bilstein equivalent part looks to be the EXACT same part as the Genuine OE one. They are identical in every way, including the size, font and location of the “Made in Germany” mark, as well as the casting signatures. The only difference is the absence of the “MB Star” on the FB part and the presence of their own logo. There isn’t a huge difference in price, but then again it’s the exact same part. Also, Uncle Kent tends to like Febi Bilstein products..

Genuine OE:



Febi Bilstein:

 

[gsxr]

Good catch about the 2001 casting date, although that is not necessarily when it was manufactured - hard to say. The label date is Jan-2018.

I also bought a Febi Bilstein tensioner but it does not look exactly the same as Genuine. Febi had none of the OE part numbers embossed, no evidence of the Star logo ground off, no manufacturer logo, nada. I only like Febi when they are reboxing OEM and in this case, it was not. I need to find the Febi (misplaced in my shop, aaaargh) and take some photos next to OE when I get the Genuine part.

As noted above, be careful if you buy the INA pulley - if Trucktec in the box, I'd return it.

 

[Joncf]

Good catch about the 2001 casting date, although that is not necessarily when it was manufactured - hard to say. The label date is Jan-2018.

I also bought a Febi Bilstein tensioner but it does not look exactly the same as Genuine. Febi had none of the OE part numbers embossed, no evidence of the Star logo ground off, no manufacturer logo, nada. I only like Febi when they are reboxing OEM and in this case, it was not. I need to find the Febi (misplaced in my shop, aaaargh) and take some photos next to OE when I get the Genuine part.

As noted above, be careful if you buy the INA pulley - if Trucktec in the box, I'd return it.

Interesting. My car is a ‘93, and the casting date on my original tensioner was “92,” so I assumed it was correct. Do you know if your Febi tensioner looked anything like this?

 

[gsxr]

Yes! From memory, my Febi tensioner looked very similar to your photo, if not identical. That's a part produced specifically for Febi, but not OEM like the Febi-reboxed OEM SGF flex discs, for example.

 

[Joncf]

Yes! From memory, my Febi tensioner looked very similar to your photo, if not identical. That's a part produced specifically for Febi, but not OEM like the Febi-reboxed OEM SGF flex discs, for example.

Got it, thanks for the info! Hopefully it’s a decent quality part. I have faith in Febi!

 

[gerryvz]

In my view, both the timing chain tensioner, and belt tensioner, are important to critical items. I would ensure that both are German-made products. The MB belt tensioner is not hugely expensive, and in my opinion not an item to skimp on.

Febi in most cases reboxes Chinese or third-world-made products, with some exceptions. Febi is acceptable ONLY if they are reboxing European-made or MB OE products with the star ground off, or OEM products. Things like the SGF rubber flex discs would fall into this category. But there is PLENTY of Febi junk out there. So, buyer beware.

 

[gerryvz]

Although I don’t know the answer to that question, that’s an old stock part (2001). I’m fairly certain the manufacturer is different for the current ones being produced. The new ones don’t have that symbol, and the cast writing is in a different font, along with other very minor machining differences. I could be wrong.. that company just might not mark their logo on their products anymore.. so it’s difficult to say.

Interestingly, and unsurprisingly to me, the current Febi Bilstein equivalent part looks to be the EXACT same part as the Genuine OE one. They are identical in every way, including the size, font and location of the “Made in Germany” mark, as well as the casting signatures. The only difference is the absence of the “MB Star” on the FB part and the presence of their own logo. There isn’t a huge difference in price, but then again it’s the exact same part. Also, Uncle Kent tends to like Febi Bilstein products..

Genuine OE:

View attachment 157672

Febi Bilstein:

View attachment 157673

That photo of the "Genuine" part does NOT look like the genuine part that I posted photos of. Mine has the MB star and part number, and no COO imprinted on it like the Febi and "Genuine" products do (which do look identical, down to the color of the female Torx stud). Note that the genuine MB product has a Torx stud that is the same color as the rest of the tensioner housing, as well as a manufacturer's mark on it. I would explicitly verify that the "Febi" or "Genuine" tensioners pictured, are indeed made in Germany. And if not, they should be returned.

Febi is one of those manufacturers reboxers companies who liberally put "Germany" in their company name and product titles/boxes/packaging despite many of their products NOT coming from Germany. So while the company may be headquartered in Germany, that doesn't guaratee that the products are made there.

 

[gsxr]

Febi is one of those manufacturers reboxers companies who liberally put "Germany" in their company name and product titles/boxes/packaging despite many of their products NOT coming from Germany. So while the company may be headquartered in Germany, that doesn't guaratee that the products are made there.

Yes - you must be very careful with their products. I greatly dislike any company who puts 'Germany' in their name to imply the components are made there. Many times, the COO (Country Of Origin) decal is missing and you can't tell for sure.

Occasionally, the COO decal is present and informative:

 

[gerryvz]

Although I don’t know the answer to that question, that’s an old stock part (2001).

This is NOT an "old stock" part. Rather, it is the design/manufacturing date of the CASTING used to produce the part. As indicated and shown on the box, the actual manufacture date of the genuine part I got was in 2018. It is not uncommon for casting/tooling dates to be much earlier than when the actual part was produced.

 

[Joncf]

That photo of the "Genuine" part does NOT look like the genuine part that I posted photos of. Mine has the MB star and part number, and no COO imprinted on it like the Febi and "Genuine" products do (which do look identical, down to the color of the female Torx stud). Note that the genuine MB product has a Torx stud that is the same color as the rest of the tensioner housing, as well as a manufacturer's mark on it. I would explicitly verify that the "Febi" or "Genuine" tensioners pictured, are indeed made in Germany. And if not, they should be returned.

Febi is one of those manufacturers reboxers companies who liberally put "Germany" in their company name and product titles/boxes/packaging despite many of their products NOT coming from Germany. So while the company may be headquartered in Germany, that doesn't guaratee that the products are made there.

I do see the differences. The one I replaced looked identical to your new one, with the exact same markings.

I’m aware that Febi reboxes/rebrands many parts, but this specific tensioner does look to be “Made in Germany.”

As Dave says, it could be a part that Febi has commissioned production on, instead of using one already in production by another company:

That's a part produced specifically for Febi

 

[Joncf]

This is NOT an "old stock" part. Rather, it is the design/manufacturing date of the CASTING used to produce the part. As indicated and shown on the box, the actual manufacture date of the genuine part I got was in 2018. It is not uncommon for casting/tooling dates to be much earlier than when the actual part was produced.

I never considered this.. it does make sense actually.

 

[gerryvz]

I never considered this.. it does make sense actually.

It's the same thing with upper wiring harnesses for the 500E. There are two dates on every harness label. One date is the actual manufacture date; the other date is the design date (which essentially is a version number).

Also, Febi may commission manufacturing of a few parts on their own, but 90%+ of what they sell, is re-boxed from other manufacturers, and from what I have seen, about 80%+ of that is low-cost Chinese-made parts.

I do heartily recommend Febi for flex discs (as long as it is an OEM SGF in the box), and their SLS hydraulic suspension fluid (which is white-labeled from a legit manufacturer). It used to be that their timing chain tensioners were legit, but I don't know that this is still the case -- it may or may not be.