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1991 Ls Engine Mounts


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Hi All,

Suffering worn out engine mounts.. I know i've ran across some posts for how someone changed out the engine mounts, particularly the difficult driver side.. Anybody who has done this can you offer any pointers?

I've already changed out the transmission mount, that was really easy and my old one wasn't worn out, but the engine mounts look much harder to do?


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I did this awhile ago:


If you have access to a good independent, it might be more cost effective to just have them do it. It took me a better part of a day to do it but then again I'm just your average knucklehead. There are a LOT of things to disconnect and reconnect. I asked my indie for a quote and it was very reasonable. Having done the repair via the "unhook everything and raise the engine" route, I suspect that indies take the route of dropping the subframe to do this repair.

Others have needed to drop the subframe slightly to do this repair. I could not do it this way. I did it by removing the submounts also.


1990 LS400

1991 300CE

2000 C280

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  • 2 months later...


Completed this job last weekend.. yOu ca't believe how this improved my car..

The mounts were torn about 1/3 the way through, not separated, but probably original.. Before when I took off, It would sort of hesitate for a split second then go.. That is gone..

I had a small vibration at about 60 MPH.. That is eliminated..

At about 1500 RPMS's I would get vibrations I could feel in the foot pedal and on the floor.. And when driving same RPM.

That is gone...

The transmission shifts better and like GLASS.. I mean I don't mean the transmission itself shift better, but since the engine and transmission are where they are supposed to be there is no play at all and the whole setup is unbelievably smooth..

I had gotten used to the vibrations and such for soo long, I've had the car for 10 years, and I had gotten used to it.. But Wow, now with the new soft mounts, What a difference..

I think this although was a long day's work to do was well worth it.. Next to the rear carrier arm bushings, this is the best fix..

NOw understand my mounts weren't separated, so they still worked and were ok, but after you have new ones on you see how bad the old ones were.. Now in the summertime, or in warm climates like you Cali guys, my old mounts softened up , but in the winter, all the vibrations come out..

FOr exampe, I used to back out of my garage in the morning, and I had a vibration that was inside my door and the something in the moonroof... Now with the new mounts, NO VIB"S at all..


Thanks for all your help forum!

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Follow Glenmore's writeup.. Just make sure you take off all the PS holddowns and Go ahead and drop crossmember until the 4 bolts are almost off the threads..

1. Before you do it, get a 17MM stubby wrench... I went to sears and they didn't have a normal stubby wrench.. THe only one they had was a stubby with the rachet closed box end.. That will not work.. #1 it doesn't have the slight curve that you need, it is a flat wrench.. And also the ratcheting mechanism takes up too much room toget at either mount bolt.. Because there is 2 slits of metal on the sides of the bolt and unless you have a normal wrench you know with the slight curve on the box end, you can't get it.. You need the curve also to make the angle.... So order online a short stubby wrench 17mm.. You can do what I did and unhook the compressor bolts and move it forward and use a normal size wrench, but why, the

Stubby would be much easier.....

2.. Use jackstands.. Put on E-Brake... Jack up each side and jackstand it high.. You could also use a mech creeper if you have one, You are underneath and sand and stuff will get inyour eyes.. use eye protection.. Make sure hte car is cooled down....

3. I also had hte jackstands on and left my jack on it also just in case.. You really have to muscle to top bolts.. So Start with the pass side first.. If you can't muscle that bolt, don't even try the driver and have a shop do it.. But it really isn't that hard....I had to combine wrenches to break it loose.. Put the closed end of another wrench on the tine of the first wrench on the mount bolt.. Different than Glenmore did.. HE put an extension on the tine and banged it... I found I didn't have enough room to get a hammer or mallet inside there at all.....

4. The oil level sender, be careful, don't just pull off, it clips easily and snaps back in very lexuslike..

5. Remember all your steps when you take off the air intake and all that stuff, make sure all bolts are put back on exactly and you don't fortget a bolt...

6. Driver's side heat shield.. I couldn't fit the new mount and the heat shield in at the same time.. I mean, you can't put on the heat shield and get it in there not enough room.. Put hte mount in, not in the bolt hole yet, but lay it in there, then separately put in the heat shield then maneuver it around enough to put the shield on top of the mount , it's more feel than see.. So memorize when the mount is out how the shileld goes on.. It's easy, there is a hole, and it only goes on 1 way and you can't screw it up....

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The mounts are expensive.. But man, if you have any vibrations at all, you can feel the vib's in the floor or in the car at all, your mounts are bad...

Not mechanically bad because they probbably are not separated, it's just more of an annoyance thing... But...

Also not only does the car not vibrate at all anymore, ESPECIALLY in the cold..... But It shifts better.. Not that transmission, but since now the engine doesn't move I used to have a slight hes at say a slow roll then go..

From stop I would step on it, it would fall down for a second then go.. And sometimes the 1-2 shift would kind of shift hard..

WIth the new mounts, you can from a dead stop step on it and it shift smoooooth.. And no more slight falldown hesitation.. I thought it was spark plug related, needs tuneup, but it wasn't.. I think the worn out engine mounts were allowing the engine/trans to shift and maybe it was affecting some likage or something.. I Dunno, but it's gone now.....

Also I replaced my old transmission mount a year ago and that didn't do anything, the original one wasn't bad.....

But I also have a new Transmission mount, but it is just like my old one, the old one wasn't bad..

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WOW Fisher! Thanks a LOT for taking the time to write that. Its the little things that can make a job much easier. I don't have a garage so im waiting for summer, but when i do, I will take pics for sure. I hope i can use ramps instead of jackstands. I think a lot of LS out there are with bad mounts.

Again thanks.... :)

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