How to check loose engine or motor mount. The video shows what a loose mount will look like. The best way is to put the vehicle in drive or reverse and hold one foot tight on the brake pedal and the other foot tap on the accelerator pedal.If possible use parking brake. Go back and forth from reverse to drive and only rev the engine up once you have shifted the vehicle safely into one of the gears. Look for excessive play in the engine mount, rips or tears. http://www.professionalfleet.com