'83 300d 5 speed noise
 

So a while back (~3,000 miles ago) I swapped a 717.400 5 speed Getrag into my US spec 1983 300D. Everything went well, used a complete donor car so no modifications were needed, I used the 38# flywheel. I was able to drive the car before removing the transmission, but it had a terrible clutch and the engine was definitely on its last leg, so I was mainly just seeing if it would go through all 5 gears.

Ever since installing it, it has a slight whirring or humming noise at the bottom end of what seems like 2nd, 3rd, and maybe a little of 4th.

I replaced the following during the swap-

Slave/master
Clutch disc
Pressure plate
Throw out bearing
Pilot bearing
Trans mount
Flex discs

I'm sure there's more, just can't think at the moment.

I drained the old fluid out (looked like ATF, didn't see any metal, didn't look too dark) and replaced it with some Valvoline Dex/Merc ATF. I have some better ATF on the way that I plan on replacing the Valvoline with.

It shifts totally fine, I've taken it on a 1000 mile highway trip with no worries, but the noise is bothering me

Some notes-

-My fender liners are currently out, and I have 27" mud tires that make a ton of noise, as can be heard in the video
-The Release fork was slightly loose on its ball when I did the swap. Wishful thinking- that's the noise

Here's a video. Any ideas?

https://youtu.be/hX796lPDyN4

It may be normal noise. Standard trannys often rattle a bit at idle with the shift in neutral. Whirring may not be anything either. Is it low on lube?

5 Speed Box
 

It sure shifts smoothly .

It's fairly normal to get gear whine as the miles pile up, as no SWARF was encountered I'd switch to fully synthetic ATF and ad a magnet to the drainplug .

I like your key tag ! :rolleyes: .

Thanks!!

Another thing I forgot- when I swapped the 5 speed in, the factory sound deadening material around the 4spd auto had rotted away and fallen down. I pulled it all off. It was making the manual a pain to fit into the tunnel. So it is just straight transmission to metal tunnel.

It's full on fluid. I filled it to the top of the fill hole when I had the trans out on my bench (1.7 qts)

Car drives great, no problems at all other than the noise.

Hope this thing lasts me a while because as most all of you know... The 5 spd aluminum box is pretty rare to find

Thanks on the key chain- weird story on that.

I bought this car for $400 ~3 years ago- with the same keychain. Some time after that, I lost the keys for it completely.

After driving 4.5 hrs to the closest dealer to have a key made, I realized the ignition had been changed at some point. Drilled the ignition out and bought a new one.

My friend (who actually originally sent me the Craigslist posting for the car when it was for sale) found the same keychain on eBay for me and gave it to me as a present

So we've always joked that the "Captain's office" keychain has to stay with the car, at all times

Gear Whine
 

I hear this whine in one of my automatics .

As long as you keep it full of fluid and the noise level remains the same, no worries .

50 years ago my mother junked a perfectly good VW because she was so sure the whining tranny was going to fail .

Most of my siblings had learned to drive on that car so it's a miracle it didn't growl nor skip out of gear .

It even shifted almost as smoothly as your does .

I'm serious about the magnet and fully synthetic ATF ~ oil is the cheapest Mechanic .

Ever consider running Redline MTL gear oil? I have 10k on that post rebuild in my trans and its just great.

No lie on the magnet plug and synthetic- I still need a magnet drain plug though

Just changed with Redline D4 ATF, no change In noise. I recorded a video of what I could see through the drain/fill plugs, nothing looked bad IMO. I've been scared to run a thicker oil such as the Redline MTL- I know many people are very happy with it but why did MB recommend ATF (thin) from the get-go?

https://youtu.be/S5x2PX9haOA

You removed the sound deadning . Well that should answer your question . My manual 300D is a little whiney in second but nothing aggravating and because it only has 131,000 on it ,I'm not about to mess with it. Stick to the regular ATF ,Mercs have used it since the 50's in all their cars with manual trans without a problem and changing up to an expensive synthetic won't do anything to make the trans quiet. But if you replaced the sound deadning material....;)

Magnets And Synthetic Oils
 

Magnets because they draw the normal SWARF particles out the lubricant .

Synthetic lubricants because they lubricate so much better they pretty much stop the wear cycle dean in it's tracks wherever it is .

Until you use synthetic lubricants you'll never grasp how good they are .

Worth every penny and then some .

I rad a clapped out 1969 Honda 90C.C. Motocycle over 40,000 miles on synthetic oils and it ran sweetly until I parked it .

Synthetics always make trannies shift better too .

Thanks guys. I reinstalled my fender liners last night, maybe eventually I'll put some sound deadening back around the trans.

It is still running great with the synthetic ATF in it. The noise seems quieter when cold, gets worse with heat but never gets louder than the video posted. Even on a 400+ mile one way run, never shutting down, it never got louder.

On to other important things- such as working rear windows :)

The gear oil viscosity grade of D4 is 70W80. I would try a slightly thicker oil if the noise increases when hot, which the next step up would be MTL. Red Line recently released this MT oil that meets MB 235.10 spec of OE "manual transmission fluid", but it looks to be thinner than either.

https://www.redlineoil.com/mt-lv-70w75w


Here is additional reading on why a MT specific fluids can be a superior option than DexIII ATF.

https://www.bobistheoilguy.com/forums/ubbthreads.php/topics/5144795/re-synchromesh-manual-transmission-lubricants#Post5144795