Very bad shaking from motor.

blacklungcustoms

New Member
Dec 6, 2012
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I have been searching all over to find the answer to this problem with no luck. I have a 2000 mustang 3.8 that has a bad vibration/shaking problem. you can feel it when idling a little but when you hit the gas its bad even in park or neutral. The problem is just as bad when driving. any time you push on the gas the car shakes. From outside the car you would not even know it had a problem. Motor has plenty of power and runs great. No check engine lights or anything. I have replaced the motor mounts and the last owner said he replaced the harmonic balancer. What else could it be. Please help.
 
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How about the wrong flywheel/flex plate? Some V6's are internally balanced and some are externally balanced. Matching the wrong flywheel for the application can cause a constant vibration.
 
I took it to aamco just to see what they would say and they told me they were not sure. So im still in the same boat. I dont want to spend a bunch of money figuring it out. the person said thy did the harmonic balancer so Im guessing it has been done. is it a big deal working on a flex plate? Also could it be the torque converter? Aamco said to replace the whole motor. I thought it was way overkill. They said it could be the crankshaft. I would think that if it was the crankshaft the motor would run like bad or not run at all. Thanks for all the help.
 
You sure it isn't an ignition issue? Some spark misses can feel an awful lot like a part out of balance?

If I were you, I'd first inpect, then (assuming that checks out) run the part number on the balancer to make sure it's right for that engine. Did the previous owner have this issue at all, or is it something that just happened recently?
 
I bought the car this way because it was cheep and I figured it was just motor mounts. No check engine lights or anything. This thing shakes way to bad to just be a misfire. if I had a open bottle of coke in it would fizz all over the place. its real bad.
 
Did you ask the previous ownder if he had this issue before or after replacing the ballancer? Wouldn't be the first time I saw someone put the wrong part, on the wrong car. Run the part number.
 
I'm getting the same symptoms on my 99. Balancer is original, checks out ok visually. Did Aamco say anything about the torque converter? Keep us posted on your tests and I will do it as well.
 
The person I bought it from said he ordered the part from dealership and had someone install it. Aamco said could be flex plate or torque converter. They said it could be bad crankshaft but that seems a little odd. I really don't know where to go from here. Might just sell the car and get my money back out of it.
 
Because it goes away at certain rpms, I would probably rule out the crank because there is no flex there. The balancer, and motor/tranny mounts all have rubber in them. I replaced my pax side mount and tranny mount, but could not get the drive side mount in. My vibration gets a little better when I put the car in gear, but that could be because there is not something to resist the motor forces. We'll find it one day.
 
could b really really bad exaust drone , whats your exaust set up ? does it happen at a ceirtain speed? does it do it in park when reving ? could have to do with the egr , i know thats out there , but if the egr system is opening and closing at the wrong times it will cause a really bad idle , and it will make your engine shake a little , could be that its opening to much when reving but is operating properly at idle , idk , just throwin ideas out there for ya
 
i wouldnt do that , sounds pretty complicated , youd probably have to take it to a tune shop id think , but it would sure b a bummer if u did all that and it wasnt your problem , try this , start your car , pop the hood and remove the vacuum hose going into the EGR , if all a sudden your engine goes back to normal than your EGR is opening to soon and the EGR vacumm regulator is to blame , it may just b dirty , and u can clean it with electrical cleaner , also while u have the EGR hose unplugged feel to see if there is suction , there shouldnt be , if there is , message me back and ill tell u what to do
 
Hope you didn't buy that car in Michigan. I went to look at one before I bought my current car and it had the same problem. Started up fine, but shook like a paint shaker. The whole car vibrated and when I revved it to about 3000 it continued. I thought maybe it was a rough idle or low rpm miss that would smooth out but it was bad. I walked away from it even though the price was good.
 
I am having the same issue on my 2000 when driving it feels like u r in a massage chair. I replaced plugs wires because I thought it was a spark issue still same problem. It just started out of the blue on my way home from work. I cleaned the MAF and IAC no change to the roughness. Its there at idle its there all the way up to the rev limiter in park and in hear. It's driving me nuts trying to figure out.
 
I have been searching all over to find the answer to this problem with no luck. I have a 2000 mustang 3.8 that has a bad vibration/shaking problem. you can feel it when idling a little but when you hit the gas its bad even in park or neutral. The problem is just as bad when driving. any time you push on the gas the car shakes. From outside the car you would not even know it had a problem. Motor has plenty of power and runs great. No check engine lights or anything. I have replaced the motor mounts and the last owner said he replaced the harmonic balancer. What else could it be. Please help.
Did you ever figure out this issue ?
 
I would take the time and money to change the motor mounts also. Just because there is rubber there does not mean that it is functional rubber. It is easier to check motor mounts on a FWD than a RWD because the engine will move in a specific way (OUT of the engine bay)

If this is still an issue with your car. Pop the hood, have someone look inside of the engine bay while you have it in drive, foot on the brake and then hit the accelerator. The engine will move because of the torque. With good mounts it should cant to one side while hard accelerating and then go back to center when letting off the pedal. If the engine moves excessively then the mounts are bad.

Once you have done this repeat the same thing in Neutral and in Park. If the results are the same in all three then I would say the motor mounts might not be the factor here, if the results are worse in Drive and less in Neutral and Park then change the mounts.

It is not hard to change the mounts or too much in cost either.