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What would cause this?

Mark1972

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So had the car out for a few drives now, with no issues. Last night on 3 separate occasions during a 30 minute drive, there was a pretty loud noise(almost like a screeching.Think cutting sheet metal with a cutting disc) along with some vibration coming from under the car. We felt it in our feet. Only for like two seconds. It seemed to happen under acceleration. U-joints? It never happened during a constant speed or deceleration. Would a U-joint do that only at certain times, and not others? Not really sure where to start looking. Any thoughts would be appreciated.
 
Ujoints, torque converter, output shaft on the transmission anything that rotates.
 
Yep. Get under there and start at one end (torque convertor inspection plate off, have a look inside
for backed out bolts) - then work your way back until you find it...
...and you will find it.
 
Excellent. As always, thank you. I'll know tonight. I do remember using loctite and my torque wrench on those. I believe it was 270(22.5 ft/lbs) inch pounds. Can anyone confirm that for me please?
 
If it only happens on acceleration check to see
If fan blades are hitting shroud on radiator
Motor mount left side??
 
Perhaps a broken starter pinion gear return spring? Accelerate and the pinion slides back and contacts the flywheel (screech) until it bounces back (screech stops).
 
No issue with fan and mount. Starter spring ok. I just pulled the starter to get the thin metal cover out of the way to check the 4 bolts connecting the flexplate to the torque converter. They were all tight. I don't see any cracks in the flexplate. One thing I did notice though. Before I pulled the cover plate, I turned the engine over by hand and could hear a scraping sound coming from the torque converter location. It would only happen for like 1/8 of a rotation then go away. Once I removed the cover plate, I couldn't make it happen again. There are no signs if rubbing on the cover. That might of explained the noise I heard last night but would not explain the vibration I don't think. I haven't been able to find a single loose bolt or obvious issue. I'm still digging.
 
Do you have the correct flexplate to converter bolts in place? If the bolt heads are to thick, they can hit the backside of the block.
 
It is the original flexplate and tranny. The bolts are also original, as well as the torque converter. I couldn't find a thing last night. Not one loose bolt. Not one sign of wear or rubbing. Went for another 1 hour drive last night and no problem. When it goes in for the new gears I'll maybe just get the U-joints done and possibly the drive shaft balance checked.
 
Just a thought. Maybe under acceleration the suspension flexes enough that the drive shaft is rubbing the exhaust. If it’s close.
 
I think you are on the right track with the U joints being the next place to look. You should be able to pry on the U joints to see if there is some movement. If they are bad, it should be pretty obvious. Usually though, vibration is constant not intermittent. To me, is sounds like possibly a rock or broken spring in one of the rear brake drums. Sounds can travel and not be where you thought they were. Like others have mentioned, anything that rotates could be the culprit. Good luck. Diligence will pay off.
 
Ujoints can dry out and make noise and cause vibration even if no slack in them. The best way to check them is with the drive shaft removed.
 
So the car is going in to get looked at on Tuesday. They will be looking at the tranny, flexplate, drive shaft/U-joints, etc. Pretty much everything rotating. I've not found a thing looking myself. The brakes are an interesting culprit that I haven't pulled off. 4 wheel drums. All new but it will be worth a look as well. Thanks. As soon as I have an answer I'll post back on here what it was.
 
Just an update on the noise/vibration coming from the back of the engine, or front of the tranny that I experienced a few weeks ago. Apparently, the starter is re-engaging the teeth on the torque converter. Not sure why. Obviously the starter would have to get voltage in order for the gear to push out to engage. I pulled the starter and looked at it and couldn't see anything obvious. Now I'm wondering if this problem goes back to the steering column.
 
It's possible the starter bendix is just not returning, not necessarily getting thrown outward while driving.
When you had it out did you pull the drive gear outward and look at the shaft?
If it's not worn badly just some lube can fix that issue.
If you think somehow the starter relay is getting activated while driving, just pull the yellow wire (ignition to starter relay coil) after starting it.
Then drive around and see if you still observe the noise.
 
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