Loud light metal vibration noise mostly on left turns.

[Meryle3]

2011 Ranger PU, 2wd, 2.3L, automatic, 23,000 original miles. The truck has a Loud, light metallic, (apposed to a heavy metal clunk) noise when making left turns at slower speeds as in making a left turn from a stop or a left U-turn. A short version of the same noise is some times heard when driving straight at 30 - 35 mph over bumps, such as railroad track. Oddly, nothing on right turns. When the noise occurs in left, right angle or U-turns it is pretty constant through the turn. The noise sounds like it is coming from the entire under carriage.
Steps taken to isolate the noise:
- Bouncing on front and rear bumpers; suspension feels/sounds solid
- Check brake calipers for rocks and repacked the wheel bearings
- Checked spare tire for snugness and the truck bed bolts and bushings
- Transmission cross member and mount are tight
- Used electronic ears connected to multiple locations to pinpoint the noise; seems to be from the bell housing
- Removed the starter and the noise was louder, with and with out the ears
The transmission shifts smooth and no leaks.
My thought is possibly a cracked flex plate, near the bolts as no visible crack viewed through the starter opening and the teeth look good.
I have never had a torque converter go bad, but it seen I would feel that rather than hear it. I did not yet check the drive shaft U-joints.
The Left turn thing is odd, like something is loose and flexes in the turn and that would not affect the "flex plate" though the noise seems to be from the bell housing.
Thought I'd ask what you all think before pulling the transmission.

Thanks for any ideas or advise.

 

[pjtoledo]

exhaust system??

 

[SenorNoob]

I'd think the plate in the cable floor where a manual transmission would be or a heat shield from the description of the sound.

 

[Snatchsquatch]

Check the bolt on the steering shaft U-joint. The one under the dash on mine was snug but not tight and I was getting a similar noise. A half turn of a wrench shut it right up.

 

[Meryle3]

Thanks for the ideas!
pjtoledo, Exaust system is tight, no rattles or give.
SenorNoob, Not much shielding on this 2WD, the noise does sound similar to running you finger nails down the bubbled metal that wraps the gas tank.
Snatchsquatch, I got a quarter turn on the steering shaft u-joint, no change.

I had a friend drive in left hand circles (tried right hand circles and nothin!) while I ran along side to record the noise, see attached RangerNoise.zip

Thank you All

 

[pjtoledo]

does it consistently change in frequency with vehicle speed? put in neutral and rev the engine.
while doing the leftie slowly enlarge the circle. gradual or sudden change of noise?
does jacking the left side do anything?
is the fan hitting anything?
are the bell housing bolts tight?
take the belt off for a quick test.

before you pull the tranny, remove the 4 flex plate nuts then see if the flex plate moves.

 

[Meryle3]

pjtoledo, Pretty much the same noise though louder when accelerating into a 90 deg left turn than it is with circles in the parking lot. It does sound different from in the cab but that is expected. It is usually a short noise when driving straight over railroad tracks or bumps. Haven't heard it at high speeds. I have thought about that, putting it into neutral, then making a hard left while not under power, I'll try that. The fan was tight and not spinning freely, replace it at the beginning of this adventure. I'll look into you other ideas as well.
When you say "remove the 4 flex plate nuts", do you mean those to the torque converter? Good Idea, ... may or may not be easier than pulling the tranny as the only access is through the starter opening, hmmm, I'll take a look. Ever onward, Thanks