Is my lower motor mound bad?

[LipschitzWrath]

Guys, need your expertise. Have searched this forum (and others) and not finding a lot of info for diagnosis. Here's what happened.

I noticed my '04 GTP CompG making a clunking (maybe even a dull popping) noise, particularly when I went over bumps. Seems to be coming from right front. My first thought was suspension but on my ride home, I noticed it would do it if I rolled off the gas quickly so that was steering me away from suspension. I pulled the passenger front wheel off today and checked the sway bar end links - good. Tie rod end - good. Pulled the cover to access the mount and I don't know if its good or bad???

There are no obvious tears in the rubber that I can see. I put a jack and wood block under the oil pan and jacked it up a little bit. The mount came up maybe 1/2". Does this "play" mean its shot? As I understand it, it's a hydraulic mount so I figured there would be some give but I dunno if that's too much? Any other tests?

I guess another way of posing the question is this - should the mount "collapse" a half-inch or more under the weight of the engine?

I also tried revving the engine in park with the hood up and there is movement in the engine. Dunno how relevant this is.

I know it's cheap insurance to replace it anyways, but it looks like a mild PITA to do so I'd rather not if it isn't the source of the clunk.

Let me know what you guys think and thanks in advance!

P.S. One other thing. If it is shot, do you recommend going to a solid replacement? Preferred brand and part number?

[blueguy]

Solid option, yes.

Strange no one has replied to this yet.

I'd do both solid motor and trans mounts, your local parts store should have the option to get them they just have to order them. As for the uppers, you can flip the factory dog bone squares 90* so there isn't any movement up top, or just get poly uppers. Cheap and common. Most likely is they're shot. It's like LIM gaskets, very common. All that weight on the fluid filled mounts just crack and leak out over time, and they tear to shreds. Trans mount is a cake walk, it's harder to remove all the plastic crap in the way than it is to take off the 4, 15mm nuts holding the mount on. Motor on the other hand is kinda a two person gig, or much easier with two people...one person guiding the mount in at the wheel, while the other is up top rocking the motor into place or using a breaker bar..and it'll just settle in, but patience is key. Don't need to rip the new mount...been there, done that. Hope this helps. I always cross referenced the part# through AZ or Oriellys...what not, and then just found the solid optioned mount on EBay, where everything is cheaper anyways...and it's the same stuff you'd get at the parts store. That's up to you. I ended up running ZZP's poly uppers, poly trans, and poly motor mount. Rattled my damn fillings out of my teeth but it was one solid setup and you never had to worry about anything coming loose, lol.

[LipschitzWrath]

Solid option, yes.

Strange no one has replied to this yet.

I'd do both solid motor and trans mounts, your local parts store should have the option to get them they just have to order them. As for the uppers, you can flip the factory dog bone squares 90* so there isn't any movement up top, or just get poly uppers. Cheap and common. Most likely is they're shot. It's like LIM gaskets, very common. All that weight on the fluid filled mounts just crack and leak out over time, and they tear to shreds. Trans mount is a cake walk, it's harder to remove all the plastic crap in the way than it is to take off the 4, 15mm nuts holding the mount on. Motor on the other hand is kinda a two person gig, or much easier with two people...one person guiding the mount in at the wheel, while the other is up top rocking the motor into place or using a breaker bar..and it'll just settle in, but patience is key. Don't need to rip the new mount...been there, done that. Hope this helps. I always cross referenced the part# through AZ or Oriellys...what not, and then just found the solid optioned mount on EBay, where everything is cheaper anyways...and it's the same stuff you'd get at the parts store. That's up to you. I ended up running ZZP's poly uppers, poly trans, and poly motor mount. Rattled my damn fillings out of my teeth but it was one solid setup and you never had to worry about anything coming loose, lol.

Thanks for the reply. Do you have the part numbers handy for an '04? When I check the websites, they only seem to list a hydraulic only, no solid. Westar's website has a 2906 and 2906S. DEA Products has a 2906 and a 2906HD, but they list the HD still as a hydraulic. Anchor industries has two listings with the part number 2906 but one has a note for Supercharged. I might just have to go with the Westar mounts.

[LipschitzWrath]

Alright I thought I'd comment for other that have this problem.

The sound had been getting progressively worse over the past several days. Today I finally had some down time so I changed the motor mount (really not that bad aside from having to use an open end wrench on the top nuts) and tranny mount. The old mounts had definitely seen better days but they didn't look "failed". Took it for a test drive and the sound was still there.


Returned home home and pulled the passenger wheel again. There it was staring me in the face. The upper sway bar link bolt was loose. I checked them before and they seemed fine but not now. Best I can figure, the nut kept getting looser and looser the more I drove on it.

Hopefully this his helps someone else.

[blueguy]

Right on, glad you got it fixed.

It sure doesn't hurt though to have new mounts as well

[LipschitzWrath]

Right on, glad you got it fixed.

It sure doesn't hurt though to have new mounts as well

Yeah, they were starting to crack and I don't think they were long for this world. 170k on the car, they may not even be original. It was probably for the better. Flipped the dogbones while I was in there, now the engine is a lot more solid.

[blueguy]

I was going to say, taking care of all of that makes quite a bit of difference, you should consider taking out the U-Bend when you get some time to if you haven't done that yet either.

[LipschitzWrath]

I was going to say, taking care of all of that makes quite a bit of difference, you should consider taking out the U-Bend when you get some time to if you haven't done that yet either.

Yeah it's on the list. I am waiting for the engine to buy the farm, then I will probably rebuild it and mod it out. Intercooler and a cam, they say I should be able to drop to about a 2.8" pulley with that. My goal is 300whp and ZZP says that would be very difficult to do at my altitude (6800') and with our premium gas (91 octane). If I do that much engine work, I'd probably just spring for the ZZP headers, which have their own special downpipe. I'm a real tool about spending money on something I might end up replacing later.

Decisions, decisions.