Belt Tensioner TORTURE! 92 400E

[jc300e]

Help Fellow Forum Members.
I've replaced 3 belt tensioners in 18 months. The last one was new out of the box and did not hold tension for more that 2 days of driving. All my pullies feel free rolling without any resistence. My AC compressor does not put any noticable strain on the engine when engaged to indicate that it's delivering too much reistence.

Has anyone come across a replacement tensioner that fits? Love to find an example of an engineer and fellow M119 that got fed up with the overengeineered design and designed a simple, spring tensioned component.

Thanks
JC

[glenmore]

In the case of belt tensioners for older Mercedes, the cost/benefit is definitely on the side of an OEM part. Plus, I would guess that a MBZ part would have some sort of warranty. If you bought a URO part (~$60) instead of a FEBI part (~$125) or instead of a genuine Mercedes (~$225), you get what you pay for. If changing your belt tensioner is anything like my past 91 300CE, the hassle alone is worth the extra money of an OEM part.

A quick check of a good w124 tensioner out of the box, is the point where the pulley attaches should lie between the 2 parallel lines drawn off the flats of the bushing where the tensioning rod is attached.

[duxthe1]

It is also possible to update the setup to include a belt tensioner shock. Its been a while since I've done the mod but it involves using a 190E belt shock attached to the tensioner, run behind the waterpump pulley, and attached nearby the fan pulley. Sorry I don't have more specifics, maybe somebody else can chime in with part #s and such.

[Adler]

A original part will work others may go bad as you tighten the belt. Flawed design and pity no one has come out with a solution
regards
Ad

Originally Posted by jc300e

Help Fellow Forum Members.
I've replaced 3 belt tensioners in 18 months. The last one was new out of the box and did not hold tension for more that 2 days of driving. All my pullies feel free rolling without any resistence. My AC compressor does not put any noticable strain on the engine when engaged to indicate that it's delivering too much reistence.

Has anyone come across a replacement tensioner that fits? Love to find an example of an engineer and fellow M119 that got fed up with the overengeineered design and designed a simple, spring tensioned component.

Thanks
JC

[HarryM]

I think you are overtightening the belt.

When installing a new tensioner on M119, as soon as you get the proper tension on the belt, tighten the 19mm bolt and leave it right there. Ignore anything about any marks and pointers lining up.

[jc300e]

UPDATE: In short order, went through a Febe and Laso brand tensioner... sucked it up and bought a OE tensioner... WORKS PERFECTLY. Used the exact same installation procedure as the previous aftermarket tensioners. One note - I did find that the angle of the OE tensioner upon initial installation (with the tensioner rod completely backed off) allowed the belt to be easily slipped over the pully. Tensioning and tightening was a snap!. The aftermarket tensioners, equally slacked, did not provide the same ease of installation ???? almost as if the position of the tensioner post and internal bushing was off 90 degrees or so. At any rate, I will never buy another aftermarket tensioner. THe Benz OE part is worth the extra cash.

[JohnM.]

I've personally replaced 6 tensioners in the 5 years (90,000 miles) I've owned my 300E. And guess what? I'm doing number 7 sometime next week. Yayyyyy.

[Ferdman]

John, I suspect you are using aftermarket tensioners and not a genuine MB tensioner. Realize that most/all parts bought from a MB dealer are guaranteed for 1 year. If you are buying genuine MB tensioners then take a failed one back to the MB dealer for a free replacement.

[JohnM.]

Oh, I sure as heck am. I'm not rich enough to buy genuine MBZ parts just yet. I could probably replace the tensioner blindfolded anyhow, plus it gives me something to do. I can afford to have this attitude at 25....now 5 years from now I better be able to buy 3 of everything I replace (Genuine MBZ though)....just because.

[Brian McL]

Originally Posted by JohnM.

Oh, I sure as heck am. I'm not rich enough to buy genuine MBZ parts :

You got that backwards. Only rich people can afford to buy aftermarket because they have to replace them every year!!
Whereras the OE lasts 10 times as long and therefore cost alot less....