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Vibration at Idle in Drive - Motor Mounts? #4592142
12/02/17 02:40 PM
12/02/17 02:40 PM
Joined: Apr 2010
Posts: 215
Detroit
Kurtatron Offline OP
Kurtatron  Offline OP
Joined: Apr 2010
Posts: 215
Detroit
Hello,

I am having some frustration, and I need the collective help. I am trying to fix my friend's 2005 Mitsubishi Eclipse. It suffers from vibrations at idle speed. The entire cabin vibrates when the car is in drive, but not in neutral. When you switch from neutral to drive, the entire engine sways like 10 degrees counterclockwise (facing the front of the engine, FWD 2WD car). I replaced the easiest and worst condition mount, the front mount, but it didn't improve the vibration. The old mount was obviously bad: torn rubber, could easily remove the old rubber insert by hand etc.

But the rear mount, responsible for allowing the engine to rotate 10 degrees, is much harder to tell if it is bad. It sits by the firewall, beneath the intake manifold. A large metal plate is blocking view of the rubber insert. I took a video of the rear mount yielding to the engine sway when shifting to drive. The rubber obviously shifts position. But I can't tell if it is torn.

I am pretty certain the passenger side and driver side mounts are bad. These have torn rubber, but I don't see how these would be responsible for allowing the engine to rotate 10 degrees, because these are literally on the axis of rotation. Could these be responsible for vibration?

My question is this: what are the odds that replacing the rear mount will fix the cabin vibrations? Is this an engine tune-up issue or a mount issue? The owner took the eclipse to a mechanic prior to me and said all 4 mounts needed to be replaced. I am just trying to fix the vibration, not the engine swaying:



I'll post a link to video in a sec...

Re: Vibration at Idle in Drive - Motor Mounts? [Re: Kurtatron] #4592146
12/02/17 02:42 PM
12/02/17 02:42 PM
Joined: Jun 2003
Posts: 33,564
ME
eljefino Offline
eljefino  Offline
Joined: Jun 2003
Posts: 33,564
ME
Change 'em all. With good ones in place the so-so ones will get hammered and wrecked.

Re: Vibration at Idle in Drive - Motor Mounts? [Re: Kurtatron] #4592147
12/02/17 02:42 PM
12/02/17 02:42 PM
Joined: Aug 2008
Posts: 21,282
ON, Canada eh?
StevieC Offline
StevieC  Offline
Joined: Aug 2008
Posts: 21,282
ON, Canada eh?
Sounds like motor mounts. A good way to check is to find a reasonably steep hill. Try putting it into drive facing upwards / downwards on the hill. If it changes based on direction it's a good indicator the motor mount is a problem.

Last edited by StevieC; 12/02/17 02:42 PM.

'18 Dodge Grand Caravan GT - AMSOIL SS 5w20
'06 Santa Fe - 535,000km AMSOIL SS 0w30 / ATF
Re: Vibration at Idle in Drive - Motor Mounts? [Re: Kurtatron] #4592150
12/02/17 02:45 PM
12/02/17 02:45 PM
Joined: Apr 2010
Posts: 215
Detroit
Kurtatron Offline OP
Kurtatron  Offline OP
Joined: Apr 2010
Posts: 215
Detroit

Re: Vibration at Idle in Drive - Motor Mounts? [Re: Kurtatron] #4592169
12/02/17 03:04 PM
12/02/17 03:04 PM
Joined: Feb 2013
Posts: 11,088
Phoenix, AZ
Nick1994 Offline
Nick1994  Offline
Joined: Feb 2013
Posts: 11,088
Phoenix, AZ
Rear one will probably help.

But aftermarket motor mounts are absolutely trash. They often die after 6-12 months


2015 Hyundai Sonata 2.4L 88k Motorcraft Synthetic Blend 5w30 & OEM
2000 Toyota Camry 2.2L 231k Valvoline 5w30 & Fram Ultra
1996 Jeep Cherokee 4.0L 147k Mobil 1 HM 10w40 & Fram Ultra
Re: Vibration at Idle in Drive - Motor Mounts? [Re: Kurtatron] #4592188
12/02/17 03:23 PM
12/02/17 03:23 PM
Joined: Sep 2014
Posts: 1,486
Seattle-ish, WA
Oro_O Offline
Oro_O  Offline
Joined: Sep 2014
Posts: 1,486
Seattle-ish, WA
Originally Posted By: Kurtatron
I took a video of the rear mount yielding to the engine sway when shifting to drive. The rubber obviously shifts position. But I can't tell if it is torn.


You just did. If it's not torn, the unit should appear relatively stable.

Quote:
Could these be responsible for vibration?


Yes, they are part of the problem.

Quote:
My question is this: what are the odds that replacing the rear mount will fix the cabin vibrations?


It might reduce it slightly, or it might not. If you have four bad mounts (and it sounds like you do), fixing only three of the four is still going to leave issues. It's a system, they don't work entirely independently of one another.

Re: Vibration at Idle in Drive - Motor Mounts? [Re: Kurtatron] #4592427
12/02/17 08:35 PM
12/02/17 08:35 PM
Joined: May 2016
Posts: 718
Canada
i_hate_autofraud Offline
i_hate_autofraud  Offline
Joined: May 2016
Posts: 718
Canada

if it was a tune-up issue / misfiring, it would be worse in drive.

seem this before, even if a mount is not torn, it can still be shot.

Re: Vibration at Idle in Drive - Motor Mounts? [Re: Kurtatron] #4592489
12/02/17 09:36 PM
12/02/17 09:36 PM
Joined: Apr 2010
Posts: 215
Detroit
Kurtatron Offline OP
Kurtatron  Offline OP
Joined: Apr 2010
Posts: 215
Detroit
Ok, well I took the dive and attempted to reach the rear mount. It has been a disaster. Tool slipped from my hand, and literally chipped my tooth. Really minor Tiny chip, but still, so disappointing. So all 3 bolts that were holding the mount were rusted enough that all 3 snapped in half when I tried to undo them. So what do I do now? Any ideas?

I am so worried that I might fail. There’s no room back there to drill straight into the holes. Tomorrow I will try larger bits to drill the thing out, but does anyone have any ideas??? eek




Last edited by Kurtatron; 12/02/17 09:37 PM.
Re: Vibration at Idle in Drive - Motor Mounts? [Re: Kurtatron] #4592575
12/03/17 12:07 AM
12/03/17 12:07 AM
Joined: Feb 2013
Posts: 11,088
Phoenix, AZ
Nick1994 Offline
Nick1994  Offline
Joined: Feb 2013
Posts: 11,088
Phoenix, AZ
Can you unbolt the mounts that the motor mount bolts to? I see a bolt head.


2015 Hyundai Sonata 2.4L 88k Motorcraft Synthetic Blend 5w30 & OEM
2000 Toyota Camry 2.2L 231k Valvoline 5w30 & Fram Ultra
1996 Jeep Cherokee 4.0L 147k Mobil 1 HM 10w40 & Fram Ultra
Re: Vibration at Idle in Drive - Motor Mounts? [Re: Kurtatron] #4592579
12/03/17 12:11 AM
12/03/17 12:11 AM
Joined: Nov 2008
Posts: 9,288
Phoenix
dishdude Offline
dishdude  Offline
Joined: Nov 2008
Posts: 9,288
Phoenix
Dare I say that mount looks okay? The rubber isn't torn so no obvious visual failure.


2018 Challenger SRT 392 PUP 0w-40 Wix 57899XP
2018 GTI
Re: Vibration at Idle in Drive - Motor Mounts? [Re: Kurtatron] #4592760
12/03/17 08:16 AM
12/03/17 08:16 AM
Joined: Nov 2006
Posts: 20,574
MA, Mittelfranken.de
Trav Offline
Trav  Offline
Joined: Nov 2006
Posts: 20,574
MA, Mittelfranken.de
Support the engine underneath with a floor jack and and block of wood to take strain off the mount bolts.
Pry the mount out now the head are broken off it should be no trouble and remove the other part of the mount from the engine to improve access to the broken bolts.

Center punch the broken bolts dead nuts in the center and a small drill bit with an angle drill to drill through then enlarge the holes 1 size at a time until only the remnants of the original threads are left and pick those out with a dental pick.






























pick.


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