My mechanic recently replaced the alternator on my 2007 Toyota Camry.

When he returned the car to me he said that my motor mounts need to be replaced.

Now I notice a vibration at idle. I am not a mechanic but I am sure that vibration was not noticeable before. Did they fail in one day, or am I thinking negatively?

  • What engine size? Jul 1, 2015 at 20:18
  • Don’t change 1 top mount and not change the others 1 Is stiffer than the other it’s a nightmare.
    – Lucky
    Aug 1, 2020 at 23:21

3 Answers 3


Depending on the design of your car, the engine mounts may have been removed during the alternator removal and replacement so any damage may now show up.

Alternatively, if the alternator previously wasn't working and is now drawing on the vehicles RPM to charge the batter, the idle may have dropped (which could account for the vibration).

If the vibration only occours at idle, it may be that the idle speed needs adjustment. However, if the vibration happens across the rev range or is particularly bad (often accompanied by an audible "clunk") when pulling away or coming to a stop, it may be that you have a bad engine mount.

  • Thanks. yes it was there before but i never concentrated on it. And if i press on the gas pedal a little while idle the vibration goes away. So perhaps need some speed adjustment.
    – shakeel
    Jul 15, 2015 at 9:33

While both Paulster2's and Steve Matthews's have good answers, there is another thing to consider. The 3.5 V-6 equipped Camrys that year (not sure about the 4 cly) have what Toyota calls Active Control Engine Mounts. They use vacuum and electricity to control the mounts. Also on the 3.5 engine it's quite an extensive repair to get to the alternator off, and if during the repair a vacuum line or electrical connector was knocked off or not reconnected it might cause you symptoms.

I am not saying for sure it's the technicians fault it's just worth finding out. As Paulster2 said it may have been there but now you are paying more attention.


I think the problem was probably there before and you are just noticing it. Lots of times, the problems we experience with vehicles happens over time. Motor mounts are one such thing. They do not wear out overnight or just give up the ghost all of a sudden (in the vast majority of the cases). Most of the time, as these things wear out, we don't notice it happening. Then, when something major happens (in your case the alternator), we suddenly become hyper sensitive to how the vehicle is running or how it feels to us.

Bottom line is, you'll need more than likely need to get your motor mount(s) replaced as the mechanic suggested (if you didn't have it done already). Motor mounts will continue to wear and if not replaced, will cause more wear to the good motor mounts due to them having to pick up the bad one's slack.

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