Questionable transmission?

[SirFoxx]

Hello!

I recently picked up a 1981 300td wagon with ~217k miles. I wasn't able to test drive it when I went to go get it, but I did get a video of the engine running, and it seems fairly healthy. However, when I got it home, and went to test the tranny, my gut sank.

Before I go into the details, I do want to mention that the transmission in this car is obscenely clean compared to the motor, along with the oil (bright red, correct levels). It almost appears as if it's been replaced previously, and I'm not sure if it has the "correct" transmission for the car. The numbers on the side are 722.303 02 052648.

The issues I have are:

1. I read somewhere that the 722.3XX is a 4 speed. When I went to drive it around, I could only find 3 gears.
2. Sometimes, when going from reverse to neutral, the transmission starts making a grinding sound
3. The biggest issue I have is with reverse. When you first start the car, or let it sit for 10+ minutes, reverse works no problem. Put it in drive, then back to reverse, and nothing. I can feel what I presume the pump engaging, along with the motor loading up, but nothing else.

With what reverse is doing, does that indicate that the reverse clutch pack is worn out, or is there something else I can check?

[Diesel911]

There might be transmission applications here but I have not looked at the site for like 4 years.
http://www.europeantransmissions.com/Application.htm
You might do a google search for a free: Mercedes Transmission ASTG 722-3 722-4 manual .pdf. It has a section on trouble shooting.

If you have a pdf reader you can down load it to your comuter or simply read it.

[SirFoxx]

Originally Posted by Diesel911

There might be transmission applications here but I have not looked at the site for like 4 years.
http://www.europeantransmissions.com/Application.htm
You might do a google search for a free: Mercedes Transmission ASTG 722-3 722-4 manual .pdf. It has a section on trouble shooting.

If you have a pdf reader you can down load it to your comuter or simply read it.

Looks good, I'll see what the manual has to say. Also stumbled across this (http://jenniskens.livedsl.nl/technical/Tips/Files/722.3%20slipping%20or%20no%20reverse.pdf).

I may try this first if mercedes can still get the parts. Also, what is the proper fluid for these transmissions?

[97 SL320]

Originally Posted by Diesel911

You might do a google search for a free: Mercedes Transmission ASTG 722-3 722-4 manual .pdf. It has a section on trouble shooting.

. . . Sure if you want a pirated copy.

The ATSG gathers real world info / fixes from actual shops and does not just license a factory manual for reprint. They have stuff you will never find in a factory manual, things like a detailed breakdown of valve body - TCM use , interchange , ID for a 722.6 .

Buy the $30 manual so these guys can continue to offer great info.

https://www.atsg.us/atsg/why-atsg/

https://www.atsg.us/atsg/

https://www.atsg.us/atsg/import-manuals-1/mercedes-722-5.html

https://www.atsg.us/atsg/import-manuals-1/mercedes-722-3-722-4-mini-cd.html

[vwnate1]

It _is_ a four speed but earlier versions take off in second gear .

Next time you're at a dead stop, try manually shifting it into low then back to "D" before you begin to move, this should result in you feeling three separate shifts, indicating proper operation .

There are some adjustments you might try before giving up on this slushbox, I'd not have it repaired or rebuilt as the slightly later tranny will have the aspect of all four gears being used all the time .

I hope you at least got it for cheap as you apparently didn't test drive it ? .

Once you get this and the rest of the little niggly things sorted out it will be a fine car .

Photos, please ~ even if rough and dirty .

-Nate
(charter member of the Cheap Wagon Club)

[Diesel911]

Originally Posted by 97 SL320

. . . Sure if you want a pirated copy.

The ATSG gathers real world info / fixes from actual shops and does not just license a factory manual for reprint. They have stuff you will never find in a factory manual, things like a detailed breakdown of valve body - TCM use , interchange , ID for a 722.6 .

Buy the $30 manual so these guys can continue to offer great info.

https://www.atsg.us/atsg/why-atsg/

https://www.atsg.us/atsg/

https://www.atsg.us/atsg/import-manuals-1/mercedes-722-5.html

https://www.atsg.us/atsg/import-manuals-1/mercedes-722-3-722-4-mini-cd.html

I have 2 ATSG Paper Manuals and for convience I downloaded the pirated ones to my Computer. I use the Compunter ones more as I can share info easier.
Those manuals are also sometimes available used.

On the other hand if I am drowning I grab for anything that can keep me afloat. If a Pirate Ship is the only help I get on board.

Note I tend to try to acquire information before I might have the need for it so I don't have to scramble for it. Hence I try buy before the need. However, that does not seem to be what most people do.

[Diseasel300]

Originally Posted by SirFoxx

Before I go into the details, I do want to mention that the transmission in this car is obscenely clean compared to the motor, along with the oil (bright red, correct levels). It almost appears as if it's been replaced previously, and I'm not sure if it has the "correct" transmission for the car. The numbers on the side are 722.303 02 052648.

The issues I have are:

1. I read somewhere that the 722.3XX is a 4 speed. When I went to drive it around, I could only find 3 gears.
2. Sometimes, when going from reverse to neutral, the transmission starts making a grinding sound
3. The biggest issue I have is with reverse. When you first start the car, or let it sit for 10+ minutes, reverse works no problem. Put it in drive, then back to reverse, and nothing. I can feel what I presume the pump engaging, along with the motor loading up, but nothing else.

With what reverse is doing, does that indicate that the reverse clutch pack is worn out, or is there something else I can check?

722.303 sounds like the correct transmission for the car. All 722.3 transmissions are 4-speed. When you say you only "found 3 gears" are you referring to the gear CHANGES? If so, there will only be 3 gear changes. 1-2, 2-3, and 3-4. Sometimes if the K1 accumulator spring fails, you can get an extremely rapid 2-3 and 3-4 "stacked" shift that can make the car feel like it goes from 2nd directly into 4th.

Typically the reverse issues show up as a delay going into reverse. The point to begin worry is when the delay exceeds 2 seconds (which feels like an ETERNITY when you're the one driving).

The grinding and strange behavior sound more like the shifting lever isn't positively engaged in the correct location. How loose and sloppy is the shifter knob? It should feel tight and firm, if it feels loose, or you hear a "clink" when you shift, it's time for shifter bushings and could potentially be the only problem you have here.

[Mxfrank]

Some versions of this transmission are set up to start in second. If so, you can reliably get to first by flooring the pedal from rest. I don't think a reverse clutch pack failure is very common. It's more likely that the shifter bushings are cooked. If not that, then one of the B pistons.

[Junkman]

My 84 & 85SDs have 722.303 and start in 1st. Go through the process of checking pressure and adjusting the Boden cable. The grinding is of concern but I've gotten lucky and haven't had to deal with that.

[vtmbz]

Is there any chance your parking pawls might be making the grinding sound. Someone here mentioned shifter bushings, so theyre cheap to fix and worth checking. WHen my first trans went south the first symptom was a long wait for reverse to engage, but never heard any grinding at any time.

[SirFoxx]

I'll look into adjusting the cable. My shifter bushing are definitely shot, so I will source some part numbers for that as well. As for the only finding 3 gears, I do know mine will start in second. I have bumped it back down to first, and it seems like its only making it into 3rd gear. Though, without a working speedometer (it gets jammed around 15mph) its hard to tell if it is in fact getting to 4th gear.

Here is a quick video of what reverse is doing.

https://www.youtube.com/watch?v=4v-y5MbqP9s