The parking lock is broken on my latest purchase - a 1979 450SEL. While idling in Park after getting to work today, I noticed a periodic clank coming from the transmission area. Then I noticed I was rolling backwards.

How involved is fixing that? It seems like a simple thing and the transmission functions perfectly otherwise.

Fortunately the parking break is in fantastic shape - I'll bet the PO replaced it recently.

This is a transmission out job so I'd make sure that the shifter linkage is working correctly first. I reckon you are more likely to have trouble with the shifter linkage than a part inside the transmission.

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

If the linkage is OK..
Then removal of the rear cover on the trans is required.
MOST likely not broken. But an alignment issue with the pawl.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

Heres a picture of the pawl and associated gear in my 300D's 722.418:

__________________
Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out.
Check here for compatibility, diagnostics, and availability!

(4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!)


82 300SD 145k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k

Not really sure what I'm looking for here - can you explain a little bit? I've never done anything with a transmission except for look at it blankly from underneath and think "yep, there's the transmission."

I notice in your signature a note about cruise control. Got any advice for one that seems completely dead (stalk doesn't seem to do anything when pushed in any direction)?

This might help:


The pawl is engaged when you put the lever in to P. It locks into a notch on the parking gear (my term, not sure what actually is) The parking gear also has a worm gear on it that drives the speedometer cable (124,201,123).

I have some diagnostics you can run though, most of the time its the cruise control amplifier:
Diagnostics:
Cruise Control Amplifier Diagnostics & Amplifier Repair
How The System Works and Common Problems:
Cruise Control Amplifier Diagnostics & Amplifier Repair

__________________
Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out.
Check here for compatibility, diagnostics, and availability!

(4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!)


82 300SD 145k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k

The Parking Pawl on the 722.00_series trans is mounted just slightly different than shown.

But you must remove the rear cover to get at that problem part.
Will require a slotted socket for the rear flange & also a wide straight blade like a drag link socket for the governor spring cover.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

You can see a few pictures of a 722.1 transmission in this thread - this is the four speed version of your three speed 722.0

722.118 Automatic transmission rebuild (Monster DIY)

The parking mechanism is shown on the first page - though the pictures aren't really made for your problem!

I have read that people try and remove the nut on the output shaft of the transmission by engaging the transmission in park and then having a go at it. This might be a bit of problem if you need to do this. I reckon this kind of makes it a transmission out job as it'll be a bit of problem stopping the output shaft from turning when it is fitted to the car unless there's a way of stopping that shaft from turning with the transmission fitted to the vehicle...

...I don't know if it is possible - perhaps someone here has done it?

Anyway - nuts and covers and all the rest of it shouldn't be considered until you are sure that the linkage isn't working properly. Disconnect the shifter linkage at the transmission - turn the selector and check to see if the park pawl engages when it isn't connected to the rest of the linkage.

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

I have a 1971 250C that was diagnosed by a Mercedes mechanic with a broken pawl for the same symptoms you are experiencing. I replaced the Shifter to Transmission linkage bushings, one at each end of the rod, and fixed the problem. So..........make absolutely sure that the linkage is correctly adjusted.

__________________
Charlie.