New Motor Mounts, Now a Miss?
06-17-2010, 10:00 AM
#1
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New Motor Mounts, Now a Miss? My local Cadillac dealer just installed 2 new (stock) motor mounts & a diff bushing. (covered by 3rd party warranty) Rear end clunk is completely gone!...but now it feels like it's developed a miss at idle.
Cold or warm, the car twitches & shakes enough at idle, that the beverage in my cupholder visibly shakes & enough that I can hear the dash rattle a bit.
I promptly called the dealer & brought it back in. They "hooked it up" to something & they say the don't see anything. Invoice states as follows...
"Engine Analysis: Displays normal idle quality and characteristics for high output LS6 w/aggressive cam profile. No repairs applicable."
The car didn't shake like this before, & the dealer suggests that the new motor mounts would cause the vibrations to be more easily felt. Wouldn't new stock motor mounts do exactly the opposite?
So my question, to anyone with first hand motor mount replacement experience, is: what is likey to have gotten messed up in the process of a motor mount replacement that could cause a miss? plugs? wires? a ground wire?
Or do these cars shake at idle as the dealer suggests is normal?
It's a stock 2005 CTS-V with just under 50k on it.
Feels fine except at idle, shakes at idle when in neutral, or in gear with clutch in, doesn't matter.
Any insight in appreciated...Thanks!
Cold or warm, the car twitches & shakes enough at idle, that the beverage in my cupholder visibly shakes & enough that I can hear the dash rattle a bit.
I promptly called the dealer & brought it back in. They "hooked it up" to something & they say the don't see anything. Invoice states as follows...
"Engine Analysis: Displays normal idle quality and characteristics for high output LS6 w/aggressive cam profile. No repairs applicable."
The car didn't shake like this before, & the dealer suggests that the new motor mounts would cause the vibrations to be more easily felt. Wouldn't new stock motor mounts do exactly the opposite?
So my question, to anyone with first hand motor mount replacement experience, is: what is likey to have gotten messed up in the process of a motor mount replacement that could cause a miss? plugs? wires? a ground wire?
Or do these cars shake at idle as the dealer suggests is normal?
It's a stock 2005 CTS-V with just under 50k on it.
Feels fine except at idle, shakes at idle when in neutral, or in gear with clutch in, doesn't matter.
Any insight in appreciated...Thanks!
06-17-2010, 10:07 AM
#2
thats just the ls6... i lowered my idle to 650rpm and with the creative steel motor/tranny mounts it feels as if i had cammed the car.. it does shake a little and u can clearly feel the cam lope.. if youve never own or been in a cammed V8 car, than it might feel like a slight miss fire.
06-17-2010, 10:21 AM
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Less than 100 miles on the new motor mounts.
I don't think they installed heat shields. This is the first I've heard of them.
I'm assuming these heat shields didn't ship on the cars?
Will heat cook the new motor mounts?
Thanks for the quick responses guys!
I don't think they installed heat shields. This is the first I've heard of them.
I'm assuming these heat shields didn't ship on the cars?
Will heat cook the new motor mounts?
Thanks for the quick responses guys!
06-17-2010, 03:38 PM
#7
Yep....I was plagued with the same issues....I had the dieseling @ shutoff and slamming of the motor, so I replaced the mounts and once I did it def has a rougher idle...been told by many that it's normal, I've gotten used to it over the last month or so
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06-17-2010, 04:48 PM
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Graham
06-17-2010, 05:42 PM
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Agreed normal. Ever since i had my mounts replaced, my car has a bit more of a rougher idle. Also, Before i had the mounts replaced, my car would not go into 5th gear if i was really shifting fast. But now, it goes in like butter every time.
06-18-2010, 01:41 AM
#11
Shake, shake, shake....
Shake, shake, shake....
Shake your caddy...
'05 here - shake is noticeable... embrace it... apparently you have an aggressive factory cam. If you ever go to sell it include that documentation. It raises the resale value.
Shake, shake, shake....
Shake your caddy...
'05 here - shake is noticeable... embrace it... apparently you have an aggressive factory cam. If you ever go to sell it include that documentation. It raises the resale value.
06-18-2010, 02:03 AM
#12
thats just the ls6... i lowered my idle to 650rpm and with the creative steel motor/tranny mounts it feels as if i had cammed the car.. it does shake a little and u can clearly feel the cam lope.. if youve never own or been in a cammed V8 car, than it might feel like a slight miss fire.
06-19-2010, 08:47 AM
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I have the exact same issue with my 05 V. It shook on old stock mounts. It shook after new stock mounts. It shakes now. It also has the "diesel-ing down" issue when I shut it off. Seems like they all shake rattle and roll...
