4L60E Flexplate question

[Patch]

Picked up a 1997 4x4 GMC Sierra 1500 on Friday with what was described as a blown transmission. While starting it, the starter made a strange metallic sound and the engine seemed pretty unbalanced. After it warmed up a bit, it smoothened out considerably, and that is when you could start to hear a dragging, slight chirping sound from the transmission area. I put it in reverse...and it made no horrible noises....put it in L1 and same thing. Both times I had directional movement. Drove the truck at a hair above idle about 40 ft. with no issues. Put it in reverse and backed into the driveway space...again with no issues except the accompanying noises. I have not had the opportunity to pull the cover and inspect the flexplate, but I have a gut feeling that is the issue. The seller said this transmission had been rebuilt not long before he bought it.....so I guess we'll see shortly. Any of you ever had a failed flexplate with the same sort of symptoms? (Forgot to mention the previous owner said this all started when he was going down the freeway and the truck would not go past 55-ish mph)

[mongocanfly]

without looking?...look first ask questions later...
I've seen flexplates with cracks and twisted out centers..also seen loose bolts...check all that
I swapped a 4l60 out a month ago and there was no inspection cover on it...only way to bolt t/c to flexplate was remove the starter and go thru the hole....it was a later model though. .your 97 may have a cover

[Patch]

Originally Posted by mongocanfly

without looking?...look first ask questions later...
I've seen flexplates with cracks and twisted out centers..also seen loose bolts...check all that
I swapped a 4l60 out a month ago and there was no inspection cover on it...only way to bolt t/c to flexplate was remove the starter and go thru the hole....it was a later model though. .your 97 may have a cover

usually I would look first, but work schedule being what it is and the dang snow, I haven't had a chance to crawl my butt up under there quite yet..
No cover on the newer ones huh.....wow. Well, working on Grumman aircraft for almost 20 years has prepared me for things built within other things....lol. Thanks for the heads up.

[mongocanfly]

snow? wow...I'm sitting here at 77 degrees...I think the early ones had inspection covers so you may be ok...I know the later one I swapped didn't...

[95 S_Trucker]

Your 97 will have a cover. The exhaust pipe is in the way to get out of the way.

[Tom]

Originally Posted by mongocanfly

snow? wow...I'm sitting here at 77 degrees...I think the early ones had inspection covers so you may be ok...I know the later one I swapped didn't...

Ruff sitting in 77* in november ain't it?

[mongocanfly]

yep...just miserable. ..

[Patch]

Well....crap. Took the cover off....knelt the front of the exhaust so I could pull the cover out. No carnage found. No loose bolts, no cracks and no center ripped out. I did remove the three converter/fp bolts and pushed the converter back, started it up and climbed underneath. Horrible noise.......coming from........one of the catalytic converters! Like really bad. So...noise figured out. The only thing I found with the flex plate when running, it really looks out of balance. So much that there is a small spot on the ring gear from the starter losing full contact with it upon startup. Shut it off, bolted the flexplate back to the converter, restarted it and it still looked wobbly, but not the converter. I was stoked!!! I figured the power loss was maybe the cat being plugged (dual catalytic converters) and took it for a test spin.....sigh........it will not shift out of 2nd. Reverse works....1st works. Trying to manually shift from L1 and up doesn't affect it. So.....I guess I am looking a transmission after all.....I'll keep trouble shooting it...but it's looking that way.

[mongocanfly]

fix one thing find another...sounds like my luck....

[Patch]

Well......crap. Finally pulled the pan off....not good......not good at all. Top side of the filter has aluminum shavings on it......the bottom of the pan looked almost like aluminum paint......sighhhhhhh. Now looking for a replacement or rebuild.