QuestionI have brought it to get checked and i am hearing 2 different things. 1. Motor mounts need replacing 2. Motor mounts are fine, it is the timing belt. please help.
AnswerThere are many things that can cause vibration. Depending on the cause, the frequency of the vibration will be different. Motor mounts are a plausible cause, and, if you have the 2.4L four cylinder engine, a timing belt problem or out of time balance shaft can also be a cause. I'm going to list some potential causes of vibration below along with a description of what you can expect from each.
-- Misfire. You should notice a power loss along with this. Presuming it's missing only on one cylinder, the frequency should be about 1/2 of engine rpm.
-- Out of balance torque converter or crankshaft. This will typically be most noticeable only in a small rpm range, and the frequency should be about the same as the engine rpm.
-- Mistimed balance shaft or broken balance shaft timing belt. This will typically be worse at higher rpm and be of a very high frequency, at least twice engine rpm. Often, the vibration will be enough to make a buzzing noise in the vehicle.
-- Worn or weak engine/trans mount. This vibration is typically noticeable at most engine rpms and will typically have a frequency between engine rpm and twice engine rpm.
