Mazda Repair: 1994 Mazda 626 2.0 liter, wheel drive cars, front wheel drive cars

Question
My sister in law just recently purchased this car and it shakes and vibrates very bad while in drive or reverse and purrs in neutral and park. RPMs are around 500 at idle, if you put in drive and hold the brake and give it a little gas the vibration will go away. What is causing this problem? any suggestions?

I just changed the Harmonic balancer and belts. When i removed the H/B i noticed thatthe Timing belt cover has a cut in it due to the altenator belt exposing the timing belt. Is this a problem later to come?

Thanks in adavnce


Answer
Well, a harmonic balancer will do this, as well as bad motor and transmission mounts. I suggest that you remove the timing cover and check for excessive cracks or wear on the timing belt. If you do not have documentation of it having a timing belt done you would do it before it has a chance to become an issue. You can also do a tune up and a new set of plugs. I believe that you will find that a motor mount is bad or a torque strut. It is a common occurrence on many import cars, especially Hondas! That will appear to be running rough due to the lack of support allowing the engine to flop around like a landed fish! I buy a lot of my Honda Accords under the guise that they have a mysterious engine problem that no one can locate. It costs $85 for the mount and installs in an hour with the removal of the radiator “which I replace as well on principle”. They then run great and have much better traction. That is another good test of a motor mount!  Go to a parking lot and turn hard left and floor it. Then the same, but turn right. Notice a difference in which side you were turning?  Did the inside wheel hop and did you get a sharp jerking pull as you straightened out followed by a clunk or large shifting feeling in the front end?
Motor and transmission mounts have a huge effect on handling in front wheel drive cars.

Give it a good looking over and then, if you are unable to locate a problem, take it to a shop for a Diagnostic Scan to see if it is misfiring or even has a sticking torque converter.

Regards,

John