Known issues with rear top mount?

For the last few weeks I have had the following problem.

I get a sound from the drivers side rear that sounds like the kind of noise you get when sliding on a leather sofa. It's a kind of squashing rubbery sound. It happens seemingly at random and may go away during any particular journey or not. It doesn't happen on smooth roads, only over bumps and most noticeably when pulling away from a standstill as the rear squats down.

The noise can also be made to happen when stationary by pushing down on the rear of the car.

The sound is almost definitely coming from the suspension top mount. You can pinpoint it with your hearing it is that loud. Also, you can feel a vibration through the mount but nowhere else. The part is stock Toyota, none of your fancy stuff for me.

I had the mount replaced but the noise is still there although not as frequent. One thing me and my mechanic noticed is that the part has had three revisions from Toyota. Was this a known issue rectified by them and could it be that we have been supplied an old part?

My mechanic believes that the rubber inside the mount is not bonded on thus allowing it to move about under load. Is he on the right track?

However, having read some threads on here lately could it be a wheel bearing issue? Doesn't sound like it though TBH, the sound is too high up.

Anyone?

Mate, have you driven with everything removed from the boot inc polystyrene tool holders? Believe it or not, you can fit a grown man in a supra boot! I was driving with a mate in the boot to help diagnose noises!!! lol

Deffo not the boot rubbers?

Had everything out and a man in the boot. It's definitely not the boot rubbers.

Like I said in the first post, you can pinpoint the sound with your hearing it's so loud.

Air the damper oil? if so they will need renewing.

Chris,

Do you mean air in the damper oil? Renew the oil or the damper? Sorry if that seems liek a dumb question. I'm not the most technically minded.

Also, you can feel the vibration through the top mount but feel nothing at all through the damper. Could the vibration be travelling up the bolt thing at the top of the damper and transferring into the mount?

The damper may have worn out seals, and the whole thing (reall, the PAIR) needs replacing. Sounds very much like this is your problem. Are they stock dampers (black TOKICO or yellow BILSTEIN) ones?

They are the yellow Bilsteins, Chris.

Another (possibly) dumb question. Assuming this is the problem, how do I find out for definite without buying new dampers and also, if the damper is shot would I have to replace both rears or all four?

Thank you.

Take them off and either see if they are noisy or "unsmooth" when articulated by hand, in a vice, or get them tested on a shock damper test rig. Probably easiest just to buy new and hope... You should rplace both rears as a pair, ideally all 4 of them.

How urgently should they be replaced? New dampers were on the shopping list but we had them earmarked as non-essential, something to do long-term.

Sorry Chris, more dumb questions.

Looking at the Bilstein site I note that the dampers for a Supra are gas pressure not oil. They extol the virtues of this in their FAQ section. Were the original ones (as fitted) oil pressure and would one notice any difference fitting the gas pressure dampers?

..or am I getting confused here?