406oc.co.uk

I am planning to replace elastic mounting bracket #7 (on scheme). I can use the moment and replace also #21 - it was replaced 4 years (64000km) ago with alternative brand and I suspect it is not in good condition. The question is: Is there specific symptoms if #21 is for replacement? I have small vibrations in steering wheel and think they come from #7.

I would say that's very unlikely.
You most lilely have a wheel balance or tyre irregularity issue. Try swapping your spare with all of the others in turn to prove it either way.
The most common engine mounting issue is with the right hand bracket (31) or more specifically the bush (32).

If you decide to change that, make sure you note the orienation of the original bush - it's possible to accidentally fit it incorrectly.
The rubber element of the bush has 2 sections that join the inner and outer parts. The central part won't float much on this axis, but will readily do so at right angles to it. If you install it 90 degrees out from the origanal it will transmit rather than absorb vibrations


When worn, this bush can give more vibration but definitely allows the engine to 'rock' backwards and forwards. Can lead to failure of the flexi section of the exhaust

I have replaced #32 and #12 with genuine parts but not sure whether orientation is correct. About #7 - I think there is visible tear.

I haven't owned a 406 for years, so can't advise the correct orientation, but I think you could find it on this site with a 'lower engine mount' search.

If there's visible wear and tear on #7, you probably should change it.

I still think vibration felt through the steering will turn out to be wheel / tyre related - even a rear wheel can do it.