* No year and model was given with the question but my reply applies to all the Mercedes I've worked on over the years. There may be a Mercedes model 50 years ago that had a grease fitting on the steering idler, but I haven't seen it.
* Alberto, don't pack it in grease on assembly. There's usually just enough assembly lube (not chassis grease) on the bushings for an easier press fit. Notice also that there's no grease fitting for adding grease after installation. Pay attention to the correct placement of the spacer and to the correct torque spec. This is usually where the mistakes are made. Don't just slam it tight with an impact gun.

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