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Motor Mounts


Gumart1

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I am in the middle of changing out my motor mounts and need some quick advice. First of all, thanks 95LSBOB for a great write-up, but thank you Glenmore for all your assistance and PM's! If you are out there, please feel free to chime in.

I have all the nuts off the old mounts. The Driver's side was hard to access but not all that bad with the proper extensions.

I'm about to raise the engine using a small cut of a 2x4 across the oil pan, as far to the rear of the oil pan that I can place it.

From what I can see, the crossmember is held by 4 nuts, 2 on each side near the outer part, and 4 bolts near the center of the crossmember. Do I remove the bolts entirely and loosen the nuts visually? What happens if I over-loosen the crossmember? What's the best way to do this? Has anyone with a 90-94LS successfully changed the mounts without removing the submounts?

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I had just done the mounts replacement, without removing those bolts. During my Timing belt and water pump change. it was quite easy to do it, as half of the parts had to be removed for fitment. Therby making easy for the lift of the engine.

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I am in the middle of changing out my motor mounts and need some quick advice. First of all, thanks 95LSBOB for a great write-up, but thank you Glenmore for all your assistance and PM's! If you are out there, please feel free to chime in.

I have all the nuts off the old mounts. The Driver's side was hard to access but not all that bad with the proper extensions.

I'm about to raise the engine using a small cut of a 2x4 across the oil pan, as far to the rear of the oil pan that I can place it.

From what I can see, the crossmember is held by 4 nuts, 2 on each side near the outer part, and 4 bolts near the center of the crossmember. Do I remove the bolts entirely and loosen the nuts visually? What happens if I over-loosen the crossmember? What's the best way to do this? Has anyone with a 90-94LS successfully changed the mounts without removing the submounts?

Hey Gumart1!

I initially tried dropping the crossmember but it was only a half hearted attempt as I wasn't sure what I was getting myself into. On one side I was only able to loosen one of the nuts and I couldn't budge the other one even with my biggest cheater bar. I remembered one post by someone who suggested to remove the submounts and upon looking at it, this seemed the way to go. Both submounts are easy to get to and straight forward. You've done the hard part by getting the 2 upper mount nuts. With the engine resting on the old mounts, I would crack all 8 of the nuts/bolts (don't remember now whether they were nuts or bolts), and then raise the engine with the board under the oil pan. Finish removing the submounts and mount. Pull off the heat shield from the old mount and clip it on your new mount and reinstall.

Good luck!

glenmore

1990 LS400

1991 300CE

2000 C280

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I had some difficulty reaching the back submount bolts, so I decided to raise the engine to see how far it goes. I managed to get it pretty high, and was able to get the driver's side mount out! I'm so excited, because the old one was soooo compressed. This should make a huge difference! Still can't get the passenger side out, probably because it's not as compressed.

So I loosened the 4 nuts and 4 bolts on the crossmember. The nuts and bolts are somewhat loose (didn't want to go too far) but the crossmember hasn't dropped at all. I'd like to know if I am missing any nuts/bolts or if I have to hit the crossmember with a rubber hammer to break it free? I want to lower it a safe distance but I'm unsure what the limit is. I assume I am safe as long as the engine is being supported by the jack. I have read the other threads on dropping the crossmember but still need help over this hill if anyone else has done this job. Thanks!

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Gumart just sent a reply to your PM. Should have read this thread before I sent. Wasn't sure what you were doing. Yes IIRC as long as you have the engine supported you are fine to remove the crossmember.

Not sure why yours is not dropping.

I've gone out to the garage to see if I could remember exactly what I did and am having trouble. I know for a fact that I jacked up the engine to get the mounts out.

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Well, I've gotten some great replies from some very helpful members here but my crossmember is not budging with 2 nuts and 2 bolts loosened :cries: . I also hit it pretty hard with a block of wood and a hammer. I'm either missing a hidden bolt or it's frozen or I'm doing something else wrong. I have the car on jackstands on its rails, and the engine jacked up almost touching the firewall. If I can't lower the crossmember, I'll give in and remove the submounts, but they aren't very easy to access either. Does anyone have any info or diagrams on the crossmember removal? Thanks again...

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Well, I've gotten some great replies from some very helpful members here but my crossmember is not budging with 2 nuts and 2 bolts loosened :cries: . I also hit it pretty hard with a block of wood and a hammer. I'm either missing a hidden bolt or it's frozen or I'm doing something else wrong. I have the car on jackstands on its rails, and the engine jacked up almost touching the firewall. If I can't lower the crossmember, I'll give in and remove the submounts, but they aren't very easy to access either. Does anyone have any info or diagrams on the crossmember removal? Thanks again...

Sorry I have not been here on line very much.

When I did mine...I did not remove any crossmember. I just jacked up the motor and got the new mounts in there. It is crowded but I got them in there.

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95LS400Bob - Great to hear from you! I know it's been awhile, but it appears from your posting that you did lower the crossmember. Here is your original post:

"The mounts are indexed so they only go one way. Heat shield is important and must go back in place. Since the motor couldn't go up...that meant the crossmember had to come down...at least a little to give me room to get the mount in. So I loosened the crossmember (17MM deep socket) and let the crossmember lower enough to get the mount in.

Then I did the driver side...had to lower the crossmember a little more. Soon as I had both mounts in place...then I tightened the crossmember back up."

So I am wondering exactly HOW you loosened the crossmember and if you ran into any issues?

I have jacked the engine as high as it will go, and I can see that because the mounts are compressed to different levels that some people might be able to just get them out from raising the engine alone while others cannot.

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Man I'm not much help as I can't remember exactly how I loosened the crossmember. Just know that I did.

Glad to hear you have the car on the frame rails as I believe I told you incorrectly in my PM to you.

From looking under the car it seem that there are only four bolts holding the crossmember on. Wish I could be of more help......or have a better memory.

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Arkansawyer thanks for your last post and to the others for your help. Ahhh, I did it at last!!! I was able to jack the motor higher with multiple jacks centered closer to each mount. I also found that there was a point of resistance where the whole car started rising but that by pushing the limits a bit the motor went even higher and there was enough room. The motor was definitely resting against the firewall and had reached it's limit. The passenger side was an extremely tight fit for the new mount. I'm positive I removed all the nuts/bolts from the crossmember but I never did get it to lower. But I was amazed at how much space I had to work with on the driver's side as far as fitting the new mount. I still have to finish assembling everything. My old mounts were very crushed so I expect a nice improvement! Thanks again.:cheers:

By the way, does anyone know the correct torque specs for the 2 nuts and 2 bolts for the crossmember?

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Where did you guys purchase your motor mount from? Dealer? What is the estimate time to work on these mount? Does the clunk sound will go away after the new mounts are install? Right now, every times I shift from Park to D rive the clunk noise is sound. Especially the noise is louder when the engine was not warm up enough, the RPM is still at 1600-1800. but at 600 rpm clunk noise is not so loud

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Where did you guys purchase your motor mount from? Dealer? What is the estimate time to work on these mount? Does the clunk sound will go away after the new mounts are install? Right now, every times I shift from Park to D rive the clunk noise is sound. Especially the noise is louder when the engine was not warm up enough, the RPM is still at 1600-1800. but at 600 rpm clunk noise is not so loud

Unfortunately dealer is the only source for this part. I did not have a clunk when shifting from Park to Drive. In hindsight, what was obvious was the fluttering of the hood while driving. I did have a mini-van where there was a clunk when shifting and motor mounts was the problem.

glenmore

1990 LS400

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