mercedes 300e 3.0L transmission problem

[hammer300e]

hi im new to the mercedes world, and now i have gotten a crazy shifting problem an i dont know where to start can someone please help. and it doesnt want to move in reverse

[JamesDean]

Welcome.

Can you be more specific about the problem? Reverse does not work? What about the forward gears?

What year 300E?

Where are you located?

[hammer300e]

92 mercedes 300e 3.0L sorry yes the forward gears work but even in drive after hitting 2000 rpm they jump rpm and and i gotta pump the gas for it to catch gear,or just let off on the gas pedal, from tx

[hammer300e]

and o by the way its has 153,000 miles on it. i just dont know where to start is a transmission rebuild hard to do. on these cars

[JamesDean]

Let me see if I have this right:

-No Reverse
-Forward Gears will work but they will flare/slip a lot.

Do you have all forward gears? Or Just the 1st gear?

Do they all slip and flare the rpms? Or just the 1st gear?

[JamesDean]

I've never rebuilt a transmission myself so I cannot comment. I know a reputable place to purchase a rebuilt for ~ $1500 or so not including shipping ($250 I think).

[hammer300e]

yes correct, now i counted the shifts i guess what in 3rd i do believe that where is flares the rpm and. sorry not good at this messaging thing.but i would like to fix my problem but im lost my only vehicle.

[hammer300e]

well if i can replace a part or adjust something to maybe fix my problem would be great without that last resort of replacement transmission

[hammer300e]

is there some type of adjustment cable that runs from the transmission

[porkface]

that trans is not as easy as you'd like. given the symptoms you present, you need another 1.

there's plenty of info online about REBUILDING the 722.4 trans here and elsewhere, but i suspect most people opt for a rebuilt 1 they can just install themselves. much less time involved. good luck, chuck.

[lorainfurniture]

Originally Posted by hammer300e

is there some type of adjustment cable that runs from the transmission

Have you checked your fluid? Is it low, high, brown/burnt?

[JamesDean]

There are only two external adjustments for the 722.3/4 series transmissions.

1) Bowden Cable.

This cable connects up to the throttle linkage and generally affects how long the transmission will hold out gears. Roughly,it controls where the shift point occurs.

2) Vacuum Modulator

This device controls how much vaccum the transmission uses when it softens a shift. More vacuum = more clutching = more softer shift. If this is adjusted for too much vacuum flaring/slipping can result.

After you've checked the fluid level and confirmed that it is at the correct level and not burnt, I would recommend that you disconnect the vacuum line to the transmission and see how it drives. If the problems persist then you can rule out a vacuum problem. Pretty easy to do.

Some other common problems

-B2 Piston Failure (Not super common in the 722.4 more so in the 722.3)
The (infamous) B2 Piston

-Governor Gear Failure (Unique to 722.4 I believe. Plastic gear breaks and you lose upshift ability

If you do some googling you should be able to source yourself the "ATSG 722.3" which is a service manual with a troubleshooting section that might help further.

[hammer300e]

james where is the vacuum modular,an the govern thingy at and thanks guys for the help i will check them out once i locate where they are

[hammer300e]

ok guys changed out the transmission filter and torque converter fluid an the old fluid was bright red and clean not sparkling metals inside

[JamesDean]

The item marked by the red lines is the bowden cable for the transmission. Be careful as the plastic can be brittle due to years of heat cycling.



I believe the vacuum line for the transmission is just next to it. The rubber piece connected to the clear tube. You can verify this by looking where the hose goes, it should be a pretty straight shot down to the transmission.