722.4 transmission slipping after R&R

[Austintm]

This is on a 1985 300D California with 722.4 transmission.
I recently had to replace the ring gear on my flywheel because of bad starter. I installed a new starter and new flex discs while I had everything apart. I finally have everything back together and the transmission is slipping very badly. So much so that reverse will barely get me out of my driveway. Forward is just as bad. Fluid level is good, I had to replace about a quart from spillage.

[Austintm]

Turns out reading the fluid level marks on the stick isn't an accurate way of seeing how much fluid is in the system. Thought I was 1 quart low, I was closer to 3 1/2 quarts low. After filling and selecting all the gears she's finally up and running. Good to have her back.

[lsmalley]

Yeah, I just experienced the same thing today also. Glad you're back on the road.

[jake12tech]

I just serviced my 722.4 today. Did the K1 kit (2/3 flare). My reverse ticked today for the second time so I'm just waiting for the day for that to fail to do a 722.3 conversion.

[Austintm]

What sort of converting is necessary? I had always assumed the 722.3 would plug right in to my w123. Still on the lookout for a good one to have on standby. My transmission works just fine (when there's fluid in it that is) but I've heard so many horror stories about the 722.4.

[jake12tech]

Originally Posted by Austintm

What sort of converting is necessary? I had always assumed the 722.3 would plug right in to my w123. Still on the lookout for a good one to have on standby. My transmission works just fine (when there's fluid in it that is) but I've heard so many horror stories about the 722.4.

I have not done a 722.4/722.3 swap on a w123, but on the w124 it's completely different. For the swap on the w124, I recall differences between the front driveshaft. The bellhousing on the 722.4 and 722.3 are strikingly different sizes also. I've always had better experiences with a 722.3. Stronger transmission.

[MAVA]

Jake,

First, The K1 and K2 are the same spring kit.

Personally, If you have the tenacity, and the drive to replace K1. Remove and replace a transmission. You can rebuild your transmission. Lots of data exist on these. I have piles of service data and links for these Mercedes transmissions.

Lastly, the American rebuild kits contain a bonus of containing the seals for the valve body. A American rebuild kit can be bought for $180 with clutches all day long. Because you live in the USA. You have access to EPC per your vin which is a priceless feature in the rebuild process.

I would attempt a rebuild on the 722.4. My first time rebuild was 722.5 which has more parts, and I did it successfully, but the 722.5 is the less documented transmission, and I used 722.4/722.3 service manuals. The 722.3 through 722.5 are very similar, and may parts are the same. The 722.5 does not have a rear pump. Their is process to doing this rebuild, and no fancy tools buy. Just 30mm 12 point socket, some o-ring picks, and a 3" PVC coupling.

It would be a good winter project...

Anyways, my $02 cents...

Best of luck,

Martin

[liquiddog]

If you didn't use the stick how did you figure out it was low? I'm curious because I'm about to do a similar repair.

[Austintm]

I had to tilt the transmission when installing it and had some fluid loss. Hard to tell how much when it's soaked up In paper towels.

When I had everything back together I checked the fluid level via the stick. I added 1 quart and after wiping (with a piece of leather chamois) the fluid was just over the bottom hash mark. I think that's the cold mark. I idled with the parking brake on and selected all gears for a few seconds each and checked the level again. The level was again on the bottom hash mark but in either direction the car would barely move. After cusing a lot and posting the question I idled in each gear for a full 5 seconds several times over. This finally got the fluid circulating and reading low on the stick. After almost 4 quarts the level stopped dropping and I could do a full test drive.

[Zulfiqar]

the mercedes trans dipsticks are goofy.

to correctly read the 722.4 dipstick when dead cold, the fluid level is right where the end of the dipstick curls and becomes a pointer mark.

If you fill to this level, it will be 100% correct dipstick reading (right between the hot marks) level when the transmission is hot after a highway run

[Austintm]

So the two horizontal marks are Minimum and Maximum hot?

[Zulfiqar]

I never found any literature on the cold mark - the factory manual tells you to fill ATF to 7mm from the tip of the dipstick when dead cold. Which is exactly the edge of the curled pointer on the dipstick.

Everytime I follow that I never have to futz with it again.