2005 Lexus RX330
Question : My mechanic replaced the engine timing belt and then said my Lexus needed new struts. There was no vibration prior to maintenance and now there is vibration in the front end. Some people say get the tires rotated first. What should we do? I never drove the car after the timing belt replacement but before the struts so i don't know if one of these repairs caused this new problem.

Answer:
Well, that depends on what kind of vibration you have. Is the vibration in your Lexus in the engine or is it in the vehicle? Does it vibrate if you're sitting in park with your foot on the brake and hit the gas a little bit, or does it only vibrate when the car is rolling and does it change with higher rolling speed. If there was no vibration before the timing belt was replaced this sounds like you have an engine vibration. This could be caused by the engine not being properly timed or possibly the mechanic damage something like a sensor or a spark plug wire during the repair on your Lexus.

It is possible the engine has a worn engine mount or the mechanic left one loose. This will allow the normal engine vibrations to be enhanced and travel through the whole vehicle.

If you are sure it's not an engine vibration, and it only does it when the vehicle is moving, struts would not cause that. A tire could cause that as well as any number of front steering or suspension components. Vibration caused by tires normally get faster as the car is driven faster so if that's the case with your Lexus then the first step would be to rotate the tires and see if that changes your problem at all. If it does then you have a tire problem. If it does not, you need to have the steering and suspension inspected for worn parts or damage. Also look at the wheels to make sure none of them are bent.