6.2 making a terrible scrapping noise

[marand9199]

I was drive at about 35 MPH in my M1009 when this loud scrapping noise that sounded like it was right underneath me started. It got faster and louder when I gave it a little gas so I shut it down and coasted to stop, looked around under hood and truck but saw nothing unusual. I started it up again after a few minutes...same thing. It sounded like the flex plate was scrapping on something. Had it towed home and remove the flex plate stone guard and found nothing visually wrong. The day before I was getting a LOW COOLANT warning light going on and off while driving. This warning light did not happen the next day when the scrapping started.
Any ideas???

 

[wayne pick]

If it only happens when the truck is rolling, check the front brakes, the pads may be down to metal.

 

[marand9199]

It happens when in park also. The scrapping gets louder with RPM's

 

[coop]

The noise sounds like a flex plate to me also. Mine made the same sound when it cracked. It looked ok with the dust cover off but after removing the flex plate you could see the cracks around the mounting bolts. I'm not sure about the coolant light but I'm sure someone on here will help you diagnose it.

 

[marand9199]

Thanks, I'll take a closer look at it.

 

[wayne pick]

Yup, cracked flex plate, forgot that one.

 

[marand9199]

I pulled the tranny pan and took some pics. The filter was just hanging on by the mounting bolt with the mounting hole in the filter all waddled out. Doesn't look good. Nothing in the pan except the O-ring.
Can the flex plate that much noise? It sounds like the tranny is coming apart.

 

[wayne pick]

Take a magnet to the black stuff in the pan and open the filter to inspect for fragments. Your torque converter may have come apart.

 

[Hal O'Peridol]

Front wheel bearing going out can cause horrible grinding sound.

 

[jimm1009]

That bolt hole looks normal. It is actually a slot when they are new so that as the pan is reinstalled the filter moves up and the slot is needed for this.
If you look at the hole in the filter once you have it off you will see the pressed (formed) metal around the hole.
Obviously the pickup tube was not connected so it was cycling dirty or unfiltered fluid.
A new filter will fix you up unless you do have another problem.
You can get a way with installing a overhauled torque converter and new flex plate without overhauling your tranny but don't ever reinstall a used torque converter. with a freshly overhauled tranny. You will be sending junk back into the tranny and it won't last long.
There is supposed to be a magnet in the pan around the small raised dimple in the bottom of the pan. I did not see it so it could be missing but I'm sure you can tell for sure. I got about 220,000 miles out of my tranny before it wore out and then I rebuilt it myself for around $550 in parts with my labor. I purchased a DVD for about $20 and if you want I can burn a copy and send it to you. It is very handy IF you are thinking of rebuilding yours.
Good luck,
jimm1009

PS: You can replace the flex plate without completely removing the tranny from the truck but it will have to be disconnected and moved back about 2 inches to get to the bolts on the crankshaft. Make sure you either buy new bolts or you put locktite on the ones you have as you reinstall them. This goes for the bolts in the crankshaft and the torque converter.

 

[coop]

Yes, a cracked flex plate makes and awful noise and yes it gets louder with RPM. I know the sound from experience. The guy I bought my M1009 from had just replaced the tyranny. After 500 miles it started making a horrible sound which turned out to be the cracked flex plate. I replaced it with a after market part and after 500 mile it broke again. So this time I found an OEM GM flex plate and installed it paying attention to all mounting surfaces and even using my dial indicator to make certain there was no excessive end play and that the crank and output shaft on the transmission ran true. Put it back together and about 500 mile later that horrible sound was back. By this time I am so PO I decide to drop the transmission and take it to my machine shop and find out what the heck is causing the problem. Long story short, the mounting face of the transmission was not machined true.It was off 0.150" in 180 degrees top to bottom. In other words for every revolution the plate was flexing over 1/8" ! After I remachined the face of the tyranny mounting flange the flex plate hasn't broken since. Jimm1009 is correct, you don't have to drop the transmission to change the flex plate, just slide it back a couple of inches as he said. Good luck and hope you find the cause of the noise.

 

[marand9199]

coop; you nailed it right off the bat & wayne pick also. Thanks!

The problem was the last guy to put the tranny in didn't loc-tite the bolts for the torque converter. All but one was finger tight. I was going to disconnect the flex plate from the converter and push the converter back into the trans and start it up to narrow down where the noise was coming from. If it still made noise I'd know it was somewhere on the motor. if it didn't it would be the trans area. That's when I found the loose bolts.

jimm1009; I would like a copy of that DVD for the trans rebuild. Let me know how much and I'll send you a check.

Thanks to all. This is a great web site. I've learned so much since joining you guys. You guys are life and money savers.

 

[coop]

Glad you found the the cause of the noise. the M1009's are realy nice vehicles. I love mine. Your M1009 and 101A2 look realy nice. Also nice companion riding shotgun!

 

[nyoffroad]

I'm a day late! I was just going to say check the TC mounting bolts. I had a set come loose on a civvie 6.2 truck on a trip. By the time we figured what it was the threads were stripped and no money for a new TC so we just "temporarely tac welded the bolt heads in place so I could get home. I ended up driveing it for a couple more years like that! Don't ya just love temp. repairs?

 

[jimm1009]

marand9199

I sent you a PM this evening. Sorry it took so long. They blocked my internet access at work again for a while so I can't read e-mails or posts
until the evening when I return home.

jimm1009
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nyoffroad It was a slightly different vehicle but I stripped out three holes in my son's transmission on his CJ7 so I purchased a Helicoil kit for about $35 and put new threads back in. Those helicoils are stronger than the original threads and will most likely never fail again.
I think that the tranny and transfer case on our CUCVs are also M10 threads.

jimm1009