3.8l Vibration - Engine Swap

[king_ranch]

Hello,

A while back i bought a 2002 mustang (base) 3.8 automatic for $400 on craigslist, it ran and drove fine besides the 2 spun rod bearings.

I went to the local pull-a-part and bought another 3.8 from a 2000 mustang that was a 5spd. I swapped over all the 2002 sensors onto the "new engine". I used the 2002 intake, flywheel, and sensors. I fired up the engine and it vibrated and shook the car like no tomorrow at any rpm over idle.

I did some research and found out that the 99-00 models were external balanced and the 01-04 models were internal balanced. So i went back to the junk yard and got a harmonic balancer from a 01 mustang. I spent all day getting the weighted balancer off the engine and i installed the "neutral" balancer on the engine. It still shook and vibrated the entire car, like hardcore.

I checked the motor mounts and they're fine, i checked the tranny mount and it was beyond destroyed. I replaced the tranny mount and put a new coil and nearly ALL the vibration went away! AWESOME!

However it still vibrates at idle but not when i give it gas. I'm wondering if i should put the original weighted balancer back on the engine in order to get rid of the vibration. Any thoughts??

As of now, it's a 2000 engine with all 2002 parts like flywheel, balancer, intake, sensors etc... not sure what else it could be.

 

[wmburns]

The switch between external balance and internal balance on the V6's halfway through the 2000 model year. That means that you can not just look at the model year IF the original model year is 2000.

 

[king_ranch]

I found that the exhaust on the car had a huge crack where the pipe meets the muffler, causing the entire system to hang from the car about 2". The rubber hangers had failed and were completely dry rotted. I placed a jack on the muffler and closed the gap between the pipe and muffler. I turned the car on and ZERO vibration! I'll get some new rubber hangers and weld up the muffler this week.

 

[General karthief]

Nice catch, beats tearing it all apart again!

 

[king_ranch]

So... I ended up welding the exhaust pipe back to the muffler (closed the gap). I even replaced the rubber hangers. I fired up the car and it SHAKES again! this time a whole lot less. At Idle it rocks back and forth, and when I blip the throttle i can hear somewhat of an exhaust leak on the driver side. The shaking is worst at idle and at 1500 rpm. after that it doesn't shake at all, however there is a pretty good drone on the inside. (Steering wheel shakes like crazy and drones inside the car at 1500 rpm). I removed the belt and fired the car up and it still does the same shaking at 1500 rpm, just a lot less. I can tell the belt and accessories just amplify the shaking.

I'm starting to run out of ideas on this engine. I only have 10 days before my warranty from the junkyard ends and i'm stuck with it for good.

Can someone tell me if this is worth trying: Re-install the original (weighted) harmonic balancer that came on the engine.. and then go buy a new flywheel 99-00 model that's also (weighted). (That's going to be another PITA to drop the tranny....AGAIN!)

As of now the car as all 2002 engine parts (weight less flywheel & weightless balancer).

 

[General karthief]

Balancer and flywheel has to match the year of the engine, ask the junk yard if they can get you the prodution date for the car and match the balancer and flywheel to that, or if they can tell you the production date on the engine.