Diagnostic question?

[Blue94]

Okay I am just going to lay it out and maybe someone can tell me what is wrong or a subject to search for. I have replaced my rear wheel bearings and front axles. Now when I come to a stop the motor runs real rough, the rpm’s are fine just rough in the brake pedal. I release the brake and role for a few inches and stop and it is gone. Two, there is a newly paved freeway near my house and as I drive on it I get a sound like a muffled jackhammer, not loud just aggravating since I just redid the bearings. But it doesn’t sound like the bearings did when they went bad. Three, twice now about a week apart I went to start my car and it sounded like metal on metal screeching then it went away but it felt like the car was only running on half the motor. After a few more seconds the uneven vibrations stop and the motor runs smooth.

That’s everything, I really need this car to last a few more years as I want to by another sports car not a wagon to replace ,my SVX. Any ideas?

[Aredubjay]

Originally posted by Blue94
Okay I am just going to lay it out and maybe someone can tell me what is wrong or a subject to search for. I have replaced my rear wheel bearings and front axles. Now when I come to a stop the motor runs real rough, the rpm’s are fine just rough in the brake pedal. I release the brake and role for a few inches and stop and it is gone. Two, there is a newly paved freeway near my house and as I drive on it I get a sound like a muffled jackhammer, not loud just aggravating since I just redid the bearings. But it doesn’t sound like the bearings did when they went bad. Three, twice now about a week apart I went to start my car and it sounded like metal on metal screeching then it went away but it felt like the car was only running on half the motor. After a few more seconds the uneven vibrations stop and the motor runs smooth.

That’s everything, I really need this car to last a few more years as I want to by another sports car not a wagon to replace ,my SVX. Any ideas?

Without being there, I can only take a guess. The only thing that made me think of this was your description of a "muffled Jackhammer." You may have a cracked flex plate. Again, that's just a guess, and the only thing I can think of that might cause those symptoms. Anyone else?

[Blue94]

Okay I am a little embarrassed but where is this flex plate? I listened to it again today and another way of describing it would be a helicopter sound. Anyway thanks for the tip, I think that I will have to live with it until it doesn't start one day. Thanks

[svxistentialist]

Originally posted by Blue94
Okay I am just going to lay it out and maybe someone can tell me what is wrong or a subject to search for. I have replaced my rear wheel bearings and front axles. Now when I come to a stop the motor runs real rough, the rpm’s are fine just rough in the brake pedal. I release the brake and role for a few inches and stop and it is gone. Two, there is a newly paved freeway near my house and as I drive on it I get a sound like a muffled jackhammer, not loud just aggravating since I just redid the bearings. But it doesn’t sound like the bearings did when they went bad. Three, twice now about a week apart I went to start my car and it sounded like metal on metal screeching then it went away but it felt like the car was only running on half the motor. After a few more seconds the uneven vibrations stop and the motor runs smooth.

That’s everything, I really need this car to last a few more years as I want to by another sports car not a wagon to replace ,my SVX. Any ideas?

Randy could be correct about the flex plate. The torque convertor is bolted to it, so your dealer would have to strip out the tranny to look.

The symptoms you describe elsewhere could be more than 1 or 2 problems. The "muffled jackhammer" on pavement [is this concrete with divisions and ridges?] could be caused by worn bushes in your suspension, possibly at the top of the shock turrets if your mileage is high.

The metal screeching you hear when car is cold is a loose belt. When it warms up it gets sticky and grips. Possibly the alternator belt, but check them all. Tighten if belts are good, replace if worn.

You should also check if your alternator has a worn bearing. Some members have found that a refurbished alternator give the car new life, fixes uneven running.

If you still have uneven running after this, you could also be in a need of a new MAF sensor, situated between the airbox and the intake manifold.

Best of luck,

Joe