Dreaded Bottom End Noise

[gr8regal]

Noise in the bottem end. Mostly in the start up or when power is pushed.

???? I've pulled the pan and checked the rod bearings the # 2 + 5 were bad. Replaced all the bearings( .20 over(that was on the bad bearings))

But the noise is still there.

Checked the mains today and they all look ok.


??? What else could be making this noise?? That I can check???
Pan is off and the car is up in the air(2 feet).

Now what???

Help.

 

[gr8regal]

Hello any one out there?????


Bump Bump Bump hey .

maybe you will have a unexplained noise in your bottom end, at least mine is in the car. lol

 

[DR BOOST]

rod knock makes the big end of the rods oval shaped...new bearings wont fix it. it has to come apart and have the rods resized


sorry

surej

 

[MSDGN]

Check the torque converter bolts...they can come loose and make a nasty sounding noise...like rod knock...don't just check the tightness with your fingers...they may feel tight but really aren't and use blue loctite...

 

[turbo nasty]

or cracked flex plate

 

[NC87GN]

I second reconditioning the rods. They do become oval shaped and I am speaking from experience as I conditioning them as we speak. Bottom rod bearing look fine but the top were all bronze. HTH


Mike Banas
87GN

 

[smokinttype]

Mine usta make a similar sound...but it came from a good bit of thrust in the motor. (movement of crank front to back)

 

[gr8regal]

thanks for the input.

The motor was rebuilt and sat for 3 years. so there is not much miles on it, so i did not think that the rods would have oblonged yet but anything is possible. I will check the torque converter bolts tomorrow.
Now when i checked the rods there are a couple that seem to be loose(wobble in your fingers) Is this right. Not the bolts but the whole rod.
Sure don't want to rebuild.

 

[at7we2]

another possibility

I realize the last post in this thread was a while back, so hopefully you've resolved the noise problem. However, if you haven't, it may be rod side clearance. This is a well documented problem with the 3.8.

I haven't confirmed it yet, but I believe this is what's causing a rattle/clatter in the bottom of my engine and it only has 23k original miles on it. I should know within the next few days if this is the problem with my engine.

HTH

 

[CruznTType]

Grooms engine told me the same thing-- the piston ends up in a slightly cocked position and on start up there is wobble for a few seconds creating a rattle sound. As I remember had something to do with the clearence on the wrist pin or rod bearing. Problem was solved by carefully checking clearences on rebuild to see there was not much movement. My T had this problem and it was the same noise for 3 years - never got louder or lasted longer than a second at startup.?

 

[at7we2]

thanks for your response, but the noise I'm referring to is present all the time. Actually, I can only hear it at approx. 2k rpm. Above and below that rpm, there's no noise.

 

[turbo buicks]

dont worry, im sure its nothing.

 

[Spooled85gn]

guaranteed the rods are screw'd. Depending on how long it ran with this noise depends on how much resizing needs to be done.. I had a Lumina with this problem.. squeezin' a huge bearing in there takes it away for a bit and quiets it down after that.. but thats no fix.. its a "get u by" to sell the car.. or fix..