Vibration - failed motor mount?

[Derek Pulvino]

Joe,

As nobody else has responded...I don't think what you're exepriencing is
from a failed motor mount.  I've never heard of a catastrophic event like
that with a mount, especially at speed such as you described.

Bad mounts usually happen slowly over time, and result in increased
vibration into the car at idle, and more noticeable quantities of engine
rock on and off throttle.  That said, if I'm incorrent, and one of your
mounts is destroyed to a degree that would give you those symptoms, I'd
guess you'd be able to see the mount being torn.  I can't think of what
could have happened otherwise; maybe one of the driveshafts (ie center, or
cv), but then I'd think you'd experience the vibration on deceleration as
well.  Gas mileage should not be effected by the mounts.

As to replacing a mount, I think all you'd really need to do is support the
under side of the engine with a jack, and change one mount at a time.
Getting at, and replacing the passenger side mount will be a bit tougher
than drivers.

Derek P

Message: 11
From: "Joseph Vanzeipel" <vanz9646 at uidaho.edu>
To: "200q20v Discussion List" <200q20v at audifans.com>
Subject: Vibration - failed motor mount?
Date: Mon, 3 Jun 2002 13:56:51 -0700

Ok, well I was driving home yesterday (a 9 hour drive) from my brother's
graduation.  I was behind a slow moving pickup with motorcycles in the bed
and the oportunity to pass comes.  Of course, I take it, but when I hammer
it in 4th, the engine (and it seems the whole car) starts to shake, rattle,
and roll.  I shift into 5th after the pass and get off the gas, which causes
the vibration to go away, that is until I have to cruise at around 2500
rpms, which has a bit of a vibration.  After a few hours of this, I have
indentified a few symptoms:
- its worse at rpms below 2000 (really bad when starting from a stop)
- seems to go away under deceleration
- is there when idling (and kinda bumpy too)
- worse with heavy acceleration
- decresed MPG (from CPU indicated 23 to 20, highway driving)

At first I thought a vacuum hose broke loose and alowed dirty (and/or
unmetered) air into the intake system, because it was so sudden.  Now, I'm
pretty sure that it's an engine mount due to the symptoms above.  I've never
been in a car with a busted mount, so is this what I should expect?  About
fixing it:  how much?  I don't have a hoist or access to one, so I am going
to have to make my mechanic a little richer, but by how much?

Thanks,
Joseph Vanzeipel
200q20v - 122k


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