08-24-11, 11:38 AM
I have looked and have not found anyone with the same problem as I am having with my car(05 CTS-V, only mods are custom intake and Magnaflow exhaust). Regardless of what gear I am in, if I down shift and accelerate hard I get a clunky/grinding sound for a couple seconds. For example, at about 50mph I downshift into 3rd, and when I accelerate, that grinding/clunking noise happens for a couple seconds and then goes away as I continue to accelerate. It seems to do this when I am at higher RPMs. My buddy drove next to me and said it sounds like it is coming from the front of the car. When I drive easy I don't hear the sound, and with my windows up I never hear it. Apparently it is very loud and noticeable from outside the car. I am thinking this is motor mounts that have gone out, but I am not sure as I have never needed to replace a motor mount on a car before. I was hoping to get some info before bringing it to the shop and getting raped on the charges, unfortunately I do not have the tools or know how to check on motor mounts. Thanks for any help!!!
08-24-11, 11:46 AM
Hopefully someone can help you diagnose the noise better than I can. It it helps, I knew my MMs were bad because when I would turn it off, it felt like a cummins diesel being shut down. The install really wasn't bad and not too many tools are needed. I changed my worn out ones to CS steel ones using the following videos:
08-24-11, 02:05 PM
I'm thinking MMs, too.
Do you get that roughness sound on shutdown?
08-25-11, 11:21 AM
It doesn't seem to have any unusual sounds ever, unless I drop it into a lower gear and punch it.
08-25-11, 02:18 PM
Check underneath the car for leaking out of the MM's. The fluid is originally greenish but exposed to air and drying makes it look brownish. My drivers side leaked onto the oil pan when it broke and could've been mistaken for an oil leak.
08-25-11, 11:58 PM
Who's in Dallas that has our mounts, that did the install thems selves that would like to make a few extra bucks installing DrSzabo's mounts, atleast get the car on a lift for an inspection to see if infact they are bad. This is kind of a twist....giving the doctor the bad news, usually it's the other way around. Sorry Doc, it really does sound like the mounts are bad. If you do need to go to a shop to have them replaced, don't pay for more than 3 hours of shop time. Any more than that....keep shopping.
08-26-11, 11:13 AM
if it only happens when under load and at higher rpms, are you sure its not just engine detonation? (Pinging)?
sounds like gravel in the engine.
08-26-11, 03:59 PM
thanks for the help...I will look and see if I see the fluid leaking tonight. I dont think its detonation...sounds like metal on metal, but it is tough to describe.