5MOD transmission noise

[Mullacc]

My 2004 B2300 with the manual 5MOD-r1 transmission is making noise that I am not sure if I need to be concerned about.

I have had the truck for about 6 month. It had 102k miles and I've driven it about 3000 miles so far. And have slowly fixing issues with it, other than a new catalytic converter, it been small stuff and preventative maintenance. The concern I have is with a transmission sound I am hearing. It sound like like metal on metal sound to me, but not growling or grinding, smoother than that. I am concern it is a bad bearing inside the transmission. I don't think its the throw-out bearing. I suspect the noise has been there since I got it, but never thought it was coming from a potential internal transmission issue until now. The noise is not loud enough to be noticeable without trying to hear it, in fact its really hard to hear over the engine when accelerating, the AC blowing, radio, or if anything else is rattling around and making some noise, so I just never noticed it or always attributed to other things.

So here is when you hear it. When the car is moving and in gear. Depressing the clutch (petal pushed down) doesn't stop it, It does stop when you shift to neutral. So to hear it most clearly and compare the sound of different gears. I went to empty parking lot and just let car coast at like 15mph, depressed the clutch and cycled thru the gears (2-5) without lifting off the clutch. 2nd and 4th gear are loudest. 3rd is much quieter, and 5th even quieter. I can also hear it if I coast in reverse. I think I hear it in 1st as well but that harder to test. So in actually normal driving I really only ever notice it in 4th as generally it is hard to hear it in 2nd over the sound of the engine accelerating. Also shifter does vibrate a bit more in 4th than other gears (more than 3/5 at least). The sound doesn't get noticeably louder at higher speeds, if I get up to speed and just coast to a stop in 4th (depressing clutch before it stalls) it make the same noise the whole time until the car stops moving. I tried to record the sound but the my phone cannot pick it up it sounds similar to white noise.

I changed the transmission fluid when i got the truck. I used Valvoline maxlife synthetic atf, which I understood to be fine. The magnet on the drain plug just had the normal metal fuzz no shavings or chucks. I went ahead and change the fluid again (maxlife again) yesterday, really just to check for metal. And the plug has only the super fine metal fuzz, and running a magnet thru the old fluid didn't get anything either.
This is my first manual vehicle, so I have no sense if this is perhaps a reasonable operating noise or sign of an impending issue. It shifts fine, no slipping. I was assuming the truck was going to need a new clutch soon after i got it, but after I was able to bleed clutch (I really struggled with it) the clutch really firmed up and feels great every time now.

 

[pjtoledo]

it's difficult to diagnose a noise over the internet, can't help much there.
the M5OD is usually quite durable. my 2005 now has 365,000 + miles on it with only 1 fluid change about 185,000 miles ago.

does your driveshaft have that huge collar on the front? mine came loose and needed to be removed.

 

[Mullacc]

No collar.
The reason I chose the manual was because of the durability. I think i just psyched myself out because got in the mode of listening for bearing sounds after change a legit bad AC clutch bearing, it was making a rattling/crunching sound. I am also new to wrenching on cars. Dealing and tranny issues or even changing out clutch is beyond my DIY skills so probably just going to assuming its normal/non concerning noise and just monitor it see if gets worse. Given it seems to be a reasonable transmission to source used, there probably not much savings to being extra cautious anyhow. Probably not that much more to buy a good used transmission to replace one that is completely wrecked than pay a mechanic to open up and change the bearings.

 

[scotts90ranger]

The most common metallic rattling sound on these things is the heat shields on the catalytic converters... My '97 had a rattle around 4500rpm I think (no tach) and I climbed under it and found 6 of the 12 welds on the heat shields around the main catalyst broken... I welded what I could but some of them broke again and it rattles. The dealer approved fix is hose clamps around the cat... My V8 Explorer had a rattle at one point and one of the heat shields was about to fall off, I just pulled it off for later (that was 2 years ago, apparently "later" is still ongoing )