V70 2002 D5 auto - vibration at idle question

[volvosam]

I have a slight but noticeable vibration at idle. The idle itself is even and the vibration goes away completely once the revs increase. The vibration is present in N and P, gets slightly worse in R and slightly better in D.
I guess that it is one or more of the engine or gearbox mounts; the top one looks OK (looks newish) and there is a receipt in the paperwork for all 7 being replaced at a Volvo specialist about 50k miles ago.
Are the any clues in the slightly better in Drive and slightly worse in Reverse to narrow down the culprit(s)?

[mcfe]

Yeah engine mounts is one thing, and if you want to get rid of the vibrations, you'd need to get quality parts. If you go OEM aka Volvo blue box, it's better, but things like Lemforder, Corteco and so forth will not fix them much, especially Corteco, please avoid them.

Also, the vibration can also be transmitted through the subframe mounts, so sometimes even when you replace ALL engine mounts, there can still be vibration(albeit for sure far less than now) that is transmitted from the old subframe mounts.

And finally, if you choose to replace only one mount, especially either top torque mount or lower torque rod, this will prove to be a mistake. As the new mount will experience more stress due to a failed opposite mount and will cause the new mount to fail in less than 2-3 thousand miles.
So always replace in pairs. Top torque mount and lower torque rod in tandem.

[volvosam]

Thanks for that suggestion. The car has been MOTd recently and I would have thought that subframe mounts bad enough to cause vibration would have been a problem on the MOT?
My guess is that it is one or more of the 7 mounts and wondered if the fact that it is slightly better in drive and slightly worse in reverse would give any clue as to where to focus attention? My instinct would say that the front lower mount would be the most loaded with the car in reverse.....or is my logic too simplistic?

[Simmy]

polly bush inserts are available for subframe bushes .see the si robb vid on YouTube for how to install them ps any engine mounts that were replaced over 50k miles ago will more than likely be ready for replacement again

[wynnj]

Originally Posted by volvosam

Thanks for that suggestion. The car has been MOTd recently and I would have thought that subframe mounts bad enough to cause vibration would have been a problem on the MOT?
My guess is that it is one or more of the 7 mounts and wondered if the fact that it is slightly better in drive and slightly worse in reverse would give any clue as to where to focus attention? My instinct would say that the front lower mount would be the most loaded with the car in reverse.....or is my logic too simplistic?

This points strongly towards the front and/or rear lower engine mounts which in the D5s are vacuum controlled. Get a vacuum tester such as https://www.dtcdecode.com/Volvo and follow this youtube video https://www.youtube.com/watch?v=30QDz4xnJms.
SiRobb (also known as Cheshire D5 on here) has a catalogue of really useful videos relating to P2 platform volvos and used to give lots of excellent advice on here as well; his expertise is sadly missed.

[mcfe]

Originally Posted by Simmy

polly bush inserts are available for subframe bushes .see the si robb vid on YouTube for how to install them ps any engine mounts that were replaced over 50k miles ago will more than likely be ready for replacement again

That is a terrible advice. Polyurethane inserts will INCREASE vibrations. What is important here is the hardness of the rubber, for which the Shore scale exists.

Poly is hard nearly as bad as just having a lump of metal instead of rubber.

[Simmy]

Originally Posted by mcfe

That is a terrible advice. Polyurethane inserts will INCREASE vibrations. What is important here is the hardness of the rubber, for which the Shore scale exists.

Poly is hard nearly as bad as just having a lump of metal instead of rubber.

these inserts are not like full poly bushes they just stop the slop in the worn existing rubber bushes and dont make vibration any worse they just take up the slack without going to the expense or total replacement subframe bushes . watch the vid to understand the process it was just an option the op could consider.

[volvosam]

To report back on this. There is a receipt in the car's history for replacement engine mounts without specifying which exactly. The only mount that looked bad was the lower nearside gearbox torque arm mount; the front bush looked OK but the rear one is shot. The others looked like they had been replaced at some point. Bit strange really to have left the easiest and cheapest one off the replacement list.
I bought a Lemforder replacement for £35 on ebay and got around to replacing it today - vibration completely fixed.
So if you have vibration at idle which varies according to whether the car is in drive, reverse or N/P then this mount could well be the culprit.