Bad Vibration

jefffletch47 · Feb 12, 2026

Hi all have a 2000 Mustang Base 5spd and having a shaking and vibration issue. Small backstory on the car bought it for 300$ running and driving leaking transmission fluid. Come to find out when home the tail housing on the t5 was cracked so I took it out out in a same year t5 out of another 2000 from lkq for only 200$ and now I’m here. The vibration was there before and after replacement and did get better with replacement of the trans but is still pretty bad. I’ve tried uploading a video but I’m thinking engine mounts? Attached is a picture of the drivers side mount. I’ve also ruled out misfire with a scanner tool.

nickyb · Feb 12, 2026

If you can do the work yourself,then get new motor and trans mounts,they look toasted.
Then if the vibration still exist look into driveshaft balancing,or the harmonic balancer.
You got it cheap for a reason. Or as my uncle Tony use to say " you get what you paid for"...

jefffletch47 · Feb 12, 2026

nickyb said:
If you can do the work yourself,then get new motor and trans mounts,they look toasted.
Then if the vibration still exist look into driveshaft balancing,or the harmonic balancer.
You got it cheap for a reason. Or as my uncle Tony use to say " you get what you paid for"...

I can confirm it’s not the driveshaft or rear end as it vibrates anytime whether I’m moving or not and balancer appears in good condition I figured it was mounts just wanted a second opinion thank you!

jefffletch47 · Feb 13, 2026

nickyb said:
If you can do the work yourself,then get new motor and trans mounts,they look toasted.
Then if the vibration still exist look into driveshaft balancing,or the harmonic balancer.
You got it cheap for a reason. Or as my uncle Tony use to say " you get what you paid for"...

Hey was curious if there was a way to diagnose the balancer did the engine and trans mounts vibration is way less but still there worse around 1500-2k rpm vibrations go away at 3k and above and when idling below 1500 it’s smooth as can be I don’t notice any crank wobble or belt damage and the belt isn’t squeaking and a new balancer is 250$ would love a good way to diagnose it as being a parts changer isn’t my thing

jefffletch47 · Feb 13, 2026

New update now that I’ve done some research on internally vs externally balanced engines I believe previous owner may have installed the wrong flywheel. My v6 is externally balanced as I checked and verified at the balancer. I’m willing to bet they installed an internally balanced flywheel so gonna go ahead and replace clutch and flywheel as I don’t trust previous owner work if it doesn’t fix vibration only thing it could be is the balancer

nickyb · Feb 13, 2026

jefffletch47 said:
Hey was curious if there was a way to diagnose the balancer did the engine and trans mounts vibration is way less but still there worse around 1500-2k rpm vibrations go away at 3k and above and when idling below 1500 it’s smooth as can be I don’t notice any crank wobble or belt damage and the belt isn’t squeaking and a new balancer is 250$ would love a good way to diagnose it as being a parts changer isn’t my thing

You can mark the balancer with white paint , one line from center out, drive it awhile and if you see outer ring moved even a fraction then the balancer needs to go. Shop the balancer at rockauto,lmr,cj pony,and amazon.

Mustang5L5 · Feb 13, 2026

I would think if the flywheel was the incorrect version, you would feel severe vibrations at all RPM's. It wouldn't be just a specific RPM band that you'd feel it. Above 3K i'd expect that engine to be shaking out of the engine bay.

Do you suspect at all the the previous owner dug into the car and changes things like the flywheel previously? I realize anything is possible on a 25 year old car, but there's a lot of other things I would go through before swapping a flywheel, especially if the vibration is RPM specific. A slipped ring on the balancer can cause this as well.

I mean who knows. It could be because the original owner didn't torque the clutch bolts down and now it's loose.

dgrinnan · Jun 2, 2026

I have seen tons of forum trying to figure out the vibration in the 1999-2004 Mustang V6. I fixed it. First, I had two mechanics tell me there was nothing wrong with the harmonic balancer. I convinced the 3rd one to go ahead and change it out. On the vehicle, it looked okay. I was told, usuall when one goes bad you can see it. Once it was off it still looked okay until you really studied it. The pully had slipped and was shifted out of position, which threw it out of balance. Install the new harmonic balancer and the engine is smooth as can be.

Bad Vibration

jefffletch47

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nickyb

I gotta say i never painted my nuts, Never Ever

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jefffletch47

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jefffletch47

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nickyb

I gotta say i never painted my nuts, Never Ever

Mustang5L5

That is…until I whipped out my Bissell

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