General: vacuum engine mount problem ??

[speedisgood]

Can any one help? When car revs drop to around 1000 rpm from not much higher ,say driving around a car park ,a vibration can be heard , dealer reckoned vacuum engine mounts,which have been changed and altered the sound ,but still there,sometimes worse than before, been back a couple of times now one not getting any where.No noise is noted when rev counter drops to 1000 rpm when previously driving at higher speeds,say around town.They also reckon updated software loaded too. Engine is a D5 Polester Auto .Hope you can advise

[speedisgood]

Just disconnected the vacuum pipe that leads to the mounts and noise completely gone ,not sure if tickover now more lumpy??,does any one know if permanent disconnection causes any long term damage and also if this means vacuum pump too powerful / weak???? thanks any thing I can try next ??

[R-P]

Trying to remember what the enginemounts natural status is, I think it is sucked vacuum under 1500rpm (this number varies from 1000, 1200 to 1500 depending on what documentation you read iirc).

So disconnecting it will mean it is always 'hard'. It is supposed to be softer when idling, so the engine vibrations are cushioned more.

This is if I remember correctly... it's been a while since I looked into this for other reasons.

I doubt disconnecting it will cause serious issues.

PS: sorry it took me a while to see your PM.

[speedisgood]

Thanks for that .Any ideas on why I feel the rattle when pump kicks in .It's just started being noticeable as I pull away ie move up revs at the same rpm.pump working and when I connect only one mount at a time ,no problem...both together and rattle is back ???