What causes the motor of a SC2 to vibrate at idle?

Tiny
JEFFS95
  • MEMBER
  • 2001 SATURN SC2
  • 71,000 MILES
At park or with foot on the brake and in gear the car vibrates noticabally. When accelerating from a stop and driving down the road it smooths out. But when coming to a stop again it vibrates. I noticed the top engine motor mount was not cracked, but there was almost a 1/4 of play on the front side of the rubber mount where it could shift inside the bracket when engaging the transmission from drive to reverse and then back to drive. Could this be the main cause for that vibration at idle?
I'm looking at buying this car for my son and I'm interested mainly because of the low miles and we owned a 95 SL2 with the same twin over head cam, so I'm a little familiar with the motor. Would appreciate any helpful comments.
Tuesday, August 28th, 2012 AT 5:37 AM

5 Replies

Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
If the engine is running smoothly, vibrations are mainly caused by bad engine mounts. Top engine mount is to prevent excessive torsional movenments only and the main engine and transmission mounts are the ones taking all the weight and vibrations.
The other mounts should be checked.
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Tuesday, August 28th, 2012 AT 6:11 AM
Tiny
SATURNTECH9
  • MECHANIC
  • 30,869 POSTS
Just to add to this one the most common mount to fail on that car is the upper motor mount. Especaily with the low mileage that's the only one I. Would that would have failed. If you look at the part of the mount facing the coolant tank you can see if its colasped or torn. If its the style mounting iam thinking of that would be on that car. There are two styles if you snap a pic of it I can help you a lot more on how to tell if its bad unless its really bad and then you just know its bad. Also that twin cam. Isn't exactly like the 1995 twim cam in 1999 they narrowed the head which gave it much smaller liffters. Also elimated the top timing chain guide which makes it a lot harder to tell when it needs a new timing chain by sound. Also starting in 2000 they chamged the intake manifolds on the twiln cams to. Plastic.1996 started plastic valve covers on the twin cams and very early production 1994 twin. Cams had plastic valve covers.
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Tuesday, August 28th, 2012 AT 6:47 AM
Tiny
JEFFS95
  • MEMBER
  • 13 POSTS
The top motor mount doesn't fit snug in the bracket that fits over the top of the mount. The cast of the rubber seems to be intact, but is smaller than the top metal bracket, therefore when the motor moves from torque, the rubber mount can move backwards and forwards inside the top metal bracket that fit over the top of the rubber portion of the mount. You can see a large gap between the front inside portion of the metal bracket and the rubber. The car is several miles from us and I can't take picture of it now.
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Tuesday, August 28th, 2012 AT 3:25 PM
Tiny
SATURNTECH9
  • MECHANIC
  • 30,869 POSTS
Best place to view the gap is the side facing the coolant reservoir bottle. 1 Mount you can look at it and see if it's frowning if it's frowning the mounts bad. Not mount use a 5 millimeter Allen wrench to see if you can put it in a square hole facing the reservoir. The other style mount that doesnt frown you use a ink pen disposable see if you can fit it between the part that goes on the front cover and between the mount itself. Like a bic that comes a 10 pack of pens.
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Tuesday, August 28th, 2012 AT 4:49 PM
Tiny
SATURNTECH9
  • MECHANIC
  • 30,869 POSTS
If you get that car and end up replacing the mount don't replace it with another Mount that is the 1 that frowns style when it goes bad
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Tuesday, August 28th, 2012 AT 4:51 PM

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