92 Sc400 Loud Vibration At Idle

[mower420]

Hello, for a few months now my 92 SC400 has had a horrible sounding vibration at idle (i just now have some money to try and fix it). The car runs great, and the rough idle doesnt effect anything but is pretty embarrassing at stop lights. here are the symptoms, i searched the boards and couldn't find anyone with the same problem.

-it only makes noise when stopped and in drive, i usually shift into neutral at stop lights so it won't sound so bad (but sometimes i can still hear it a little bit in neutral)

- the sound seems to be coming from the front of the engine, i want to say that its coming from around the belt tensioner assembly on the front

-there are no problems with acceleration or rough idle, everything is fine except for the annoying noise.

-the noise seems to sound "circular", like it gets louder then quieter, louder quieter, etc continuously (although sometimes it is just a constant loud buzzing vibration)

-if i tap the gas pedal and get the rpms to anything above idle the sound goes away, and it never makes any noise any time other than idling.

my first instinct is that it is the belt tensioner rubbing somehow, i probably will replace that for now since its an easy job and doesn't cost much. i've read some things about engine mounts having problems, but i dont know if these symptoms really point to that.

anyone who has had similar problems or knows what this could be would be of tremendous help! thank you.

-Lonny

[jzz30]

judging from the year the car has high mileage? if so maybe the mounts are worn. if you can duplicate the symptoms in your garage, try sliding a jack underneath your engine and trans mating area and jack it up an inch to simulate an un-smashed engine and trans mount and see if the noise goes away.

[menappi]

Why don't you have someone sit in the car while it's in drive and go listen, before you go replacing items. no need to waste money if it's not needed.

[jtdavid]

Mower, I'm having the exact same problem you describe. Did you ever resolve this issue?

[crunchtime]

Hello, for a few months now my 92 SC400 has had a horrible sounding vibration at idle (i just now have some money to try and fix it). The car runs great, and the rough idle doesnt effect anything but is pretty embarrassing at stop lights. here are the symptoms, i searched the boards and couldn't find anyone with the same problem.

-it only makes noise when stopped and in drive, i usually shift into neutral at stop lights so it won't sound so bad (but sometimes i can still hear it a little bit in neutral)

- the sound seems to be coming from the front of the engine, i want to say that its coming from around the belt tensioner assembly on the front

-there are no problems with acceleration or rough idle, everything is fine except for the annoying noise.

-the noise seems to sound "circular", like it gets louder then quieter, louder quieter, etc continuously (although sometimes it is just a constant loud buzzing vibration)

-if i tap the gas pedal and get the rpms to anything above idle the sound goes away, and it never makes any noise any time other than idling.

my first instinct is that it is the belt tensioner rubbing somehow, i probably will replace that for now since its an easy job and doesn't cost much. i've read some things about engine mounts having problems, but i dont know if these symptoms really point to that.

anyone who has had similar problems or knows what this could be would be of tremendous help! thank you.

-Lonny

is it a sqeek?