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Discussion Starter · #1 ·
I was just curious into knowing how do you know if you have a bad lower motor mount. Would it cause vibrations say when you are driving on the interstate at all speeds. I have replaced the upper motor mounts and it is not as bad. Also say when i get to like 125mph I hear something rattle on the passenger side where the motor is located at. I have had a new tie rods put on, which helped some, I've had replaced the drivers side drive axle, which didn't help at all, also replaced the sway bar bushings. So I am just curious if it is the lower motor mount is shot. Any suggestions would be appreciated.

Thanks

Greg
 

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gtp_2000 said:
...Would it cause vibrations say when you are driving on the interstate at all speeds....

...Also say when i get to like 125mph I hear something rattle on the passenger side where the motor is located at...
The lower mount is like the rock of Gibraltar unless you have some loose bolts, your probably OK.

As for the high speed vibrations, it could just be your tires are a little out of balance, they ususualy only spin balance them up to about 50 or 60mph unless you ask for a high speed balance.

The rattle could be anything at that speed, maybe the lower air-dam or plastic skirts around the inner-fender buffeting in the wind...
 

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Discussion Starter · #3 · (Edited)
OK I forgot to also mention, whenever im in reverse an give the gas I get a rub\vibration of some sorts, it only does this in reverse. That is what is making me think that it could be a bad lower motor mount. I have check underneath to see if anything is rubbing but I don't see anything that could be rubbing.

Greg
 

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The lower engine mounts arent like a rock IMO.

They go bad all the time. The fact all the oil leaking from the motor collects in the cradle where the mount is located, cant help. They do go bad all the time I can assure you. The material does weaken and let the motor move too much.
 

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I agree with Ed. These can and do go bad. Infact i believe this lead to my failures last week. Yesterday i replaced them and yeah you coudl see the motor mount was bad. 78K miles on it and the last 35-40 have been hard track miles too.

i will agree that these are strock and are the foundation of yoru engine, they can go bad.
 

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GTPMORAD said:
The lower engine mounts arent like a rock IMO.

They go bad all the time. The fact all the oil leaking from the motor collects in the cradle where the mount is located, cant help. They do go bad all the time I can assure you. The material does weaken and let the motor move too much.
YUP!!!!
 

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Discussion Starter · #8 ·
Well I have fixed part of my problem with this vibration that I was getting. The wheel hub on the drivers side was bad and it does not shake or vibrate no ways near as much now. There is still some vibration though between 45-60mph. I am just wandering if the hub on the passenger side is bad also cause I have been lately hearing a low grinding sound from the passenger side until I get over 40mph. So I am gonna get that fixed soon to see if that will get rid of all of the shake\vibrations that I am getting.

Greg
 

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gtp_2000 said:
Well I have fixed part of my problem with this vibration that I was getting. The wheel hub on the drivers side was bad and it does not shake or vibrate no ways near as much now. There is still some vibration though between 45-60mph. I am just wandering if the hub on the passenger side is bad also cause I have been lately hearing a low grinding sound from the passenger side until I get over 40mph. So I am gonna get that fixed soon to see if that will get rid of all of the shake\vibrations that I am getting.

Greg
Good news.
If they have both seen the same road conditions and milage its likely that they're both bad.

When I wrote that the motor mout is like a rock, I did NOT mean that it would never go bad... I just meant that it's unlikley, especialy with the symptoms that you mentioned.

I would keep looking into other posibilities and eliminate them all, I think you're on the right track. Replacing the motor lower motor mount would be a PITA... I would only do that when you were sure that it needed to bew done.
 

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If your oil pan gasket is leaking, plan on replacing the lower engine mount while you're in there. The oil collects by the mount like posted above and should weaken the mount considerably.

Mine was pretty bad and kept me from having the fun I should have had while the Gen V was on my car.

Merc's how-to on this is pretty detailed and should help you out. There's just a few more steps if you're doing an oil pan gasket at the same time.
 

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what would those extra steps be? as i need a pan gasket on the gt BAD!

so i want to do it this weekend.

and do i just need the pan gasket? or anything else? i plan on using some sealant on the pan to gasket surface like the TSB says to compensate for the pan being made sh^&&y. so itll seal nice.

then the gtp is next, it was replced, but the guy i bought the car from had jo bobs do it and its leaking still. (along with all the other issues)

i just cant imagine taking my car to a place that is called "Two Fat Guys"
 

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But How Can You Tell?

Lots of good input but nobody answered the question, how can you tell if the motor mount has gone bad?
I, too, am wondering if mine is bad.
 

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I have recently had the same issues with my car (2001 GT). I found the half-shafts to be worn and replaced them. During the test drive, we continued to feel a slight to moderate vibration under accelaration, and found the lower mounts to be worn, however, not so severe to require replacement.

I second the comment re: wheel and tire balance. If any of your wheels should happen to be bent, this too can cause your vibrations.

So to try and answer your question, if the vibration is felt only during acceleration (no matter how light, or heavy), it very well could be your mounts.

Hope that was of some help.
 

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I have a 2002 3.8 GP GT w/55,000 miles with the same problem but mine is at 65-70 and you feel it more under load. I have replaced hub/bearing, rotors, tires and added the GM suspension kit and alignment.

I went to a trans shop and had the trans scanned (which was fine) and they checked out the mounts. GTP 2000 you may want to go to a trans shop and get your trans scanned and have them check your mounts (if you still have the problem) I have heard there are problem with these transmissions.

To check the mounts they say to look to see if they are hardened, cracking or if they are separating from the plates.

Wondering if anyone had problems like this and could recommend any other problem it may be?

Thanks
 
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