DIY Mercedes 722.3 722.4 722.5 Transmission K1 Piston Spring Repair Kit Install

[HATTENATOR]

The K1 Kit Page
2/3 Upshift Flare Repair

This is a fix for transmission slip/flare on 2-3 upshift at partial load for 722.3,722.4 and 722.5 automatic transmission


If your automatic transmission shifts fine with the exception of a flare on the shift up from 2nd to 3rd, and you've exhausted all your adjustment options, then the K1 Accumulator Spring Kit might be the solution.



The K1 spring kit,(part number 126 270 44 77) will cost you less than $10 for the 722.3 722.4 722.5 automatic transmission, that can be purchased from MB (via fastlane).The Kit is a drop in replacement for the K1 accumulator's spring/piston assembly in your transmission's valve body.



Use a 1/2”->3/8” and a 3/8”->1/2” adapters to create a short extension unless you have a real short extention. The extension is needed because the bolt is recessed pretty deeply in the pulley, but you don't want more extension because there isn't much clearance between the radiator and the pulley. These two adapters give just enough extension to reach the nut without there being much risk of banging into the back of the radiator.

Reach up from underneath, slip the socket on the nut, and rotate away. The handle is an 18” breaker bar for the leverage – more would make it easier, less and you'd need to be a gorilla to turn the engine. The socket is a 26mm. Turn only in the normal direction of rotation when the engine is running -- when facing the engine, the bolt turns clockwise.



You need to rotate the engine until the torque converter drain plug is accessible through this little hole in the bell housing of the transmission. When turning the engine, turn just a little bit each time (~10 degrees) so you'll be able to see the plug before you rotate it past the access hole. Turn much more and you're likely rotate it past the the access port and have to go all the way around again. The plug takes a 5mm allen socket.



A closeup of the transmission pan drain plug. (see the picture of the removed pan below).



The 5mm allen socket needed for the torque converter and transmission pan drain plugs.





The transmission pan has six 13mm bolts holding it to the transmission. To get to the location where the spring kit goes, it must be removed. As long as the pan is down, might as well go ahead and change the filter too.




Drop the pan and this is what you see. This shot is facing toward the rear of the car. The front of the transmission valve body has all these metal plates. We'll be removing the one on the lower Right of this picture and replacing some parts inside it. Notice that it is held in by four straight-edge, round-headed screws.. an offset screwdriver will do nicely here as they are torqued fairly tightly. Interesting tidbit, on the left edge of the valve body one can see the transmission dipstick just sticking down.. normally it sticks down further. It is slightly pulled out in case it needed to allow air into the system to help it drain.




Here's the offset screwdriver used on the valve cover place and filter screws. Given the clearance, some form of offset or stubby screwdriver is required, but the extra leverage of an offset was definitely worthwhile as the screws are torqued fairly tight. Others have cobbled together an effective offset screwdriver using a small ratchet and socket that a screwdriver bit fits into.

[HATTENATOR]

A closeup view of the cover that the spring kit fits inside.




Take out all but one of the screws and leave the cover hanging from the loosened screw (see Pic). leaving the piece there gives less risk any dirt getting on the cover while working. Under the cover you can see the little green piston holder. The internal spring has pushed it out a little here – making it very convenient to grab a hold of and slide out. There is sufficient clearance to remove and replace the green holder without any risk of damaging the two O-rings on it.




A closeup of the piston holder.




Here's what came out. The green piston holder and the internal spring mechanism. The parts inside the green holder is what we'll be replacing with the K1 spring kit.






Here's a picture of what is inside and how it was ordered. The small coil spring goes into the holder first, then the plastic-with-dual-spring valve.






The new spring kit pieces side by side with the old spring kit pieces. The large and medium spring go on the white post, the white post is (carefully and straightly!) inserted into the black piece until the assembly clicks and stays together on it's own. It takes some force, and if not done delicately and inserted at an angle, others have found out that the black piece can be cracked where the white piece is inserted.

You can't see it in this picture, but the long spring is beefier and the short spring should be weaker since it is of the same gauge but has one fewer coil. The medium spring is about the same between both assemblies.



Here's the assembled new spring kit (bottom) ready to be replaced alongside the old one (top). Here, it can be clearly seen that the new long spring is beefier and the new short spring has one fewer coils.





Installation is the reverse of removal. Briefly, put the little spring in the green holder, put the black end into the holder and make sure it fits inside the short spring. Take the assembled part and reinsert it back into the hole from where it came. Push it in, slide the cover back over it, then put the screws back in and retighten them to about what they were before. I've found no torque specification on how tight to make the screws, so I just did it by feel trying to match the previous torque. However, a word of caution – the valve body is aluminum, so it wouldn't be too hard to cross thread or over-torque the screws and strip the holes. You'd have a really bad day if you did that, so take it easy.

I did the transmission filter last. It is held in place with three phillips screws. The offset screwdriver came in handy again here for loosening the screws as they were in there pretty tight.

Clean the pan, gasket and the part of the transmission where the gasket contacts it, reassemble and torque all the bolts to specification, then add the ATF as per MBZ's procedure and off you go.


For other transmission shifting probelms you can also checkout this pagehttp://www.benzworld.org/forums/w201...-problems.html

[esequeira12]

Hello HATTENATOR,
You seem to know a bit about transmissions; I hope you do not mind me consulting with you in regards to the above mentioned. I have a 1991 190E 2.6L and just ran into the AT modulator valve change ordeal. I do not know if I might have ran the car a little too long with a low ATF level. I ran the car approximately 8 miles with a white smoke cloud behind me before I was able to stop.
Any how, The AT mod valve now changed, I am experiencing delay shifting from 2nd to 3rd gear. When driving normal it is barely noticeable but when I give it a little gas it lingers (slips) for about a second before shifting hard. I still have not tried floring it as I am afraid I only make it worse. I should mention that when finish replacing the AT mod valve I refilled with only 2qts of ATF back to normal level. Not sure about capacity but I am sure it holds more than 2 qts so it was not completely dry.
Do you thinks the problem will go away by doing the K1 kit change or this is actually something that happened and there could be more severe problems in with the transmission due to running it nearly dry?
Rgds,
Erick

[HATTENATOR]

the way you discirbe the promlem sounds just like the K1 spring problem alot of owners have. For the 10 bucks it costs for the kit and some fluid and filter I would go ahead and install the kit.

When you drove it smoking did it slip any at all.

Did it ever do this before the modulator problem

and are you sure you have no vac leaks and the modulator is adjusted correctly.

It is possible that something else could have been damaged if your tranny started slipping when you had the problem but I think it is the K1 springs.

There is also an aftermarket kit out there I never listed. It will help with alot of different shift problems on the 722.3 and 722.4 transmissions but it is more expensive but it can do alot more. This in adition to the original one being replaced first

[esequeira12]

Hello Hattenator,

Thanks for your quick reply. Before the incident it was not slipping nor did it slip during the smoking. During the smoking I did notice it shifting hard thoug and car felt as if pulling a boat (could have been loss of power due to excess ATF burning). I know for sure the ATF pretty much burned the spark plugs as I had to change them and they were burned like nothing I ever saw before(don't know how the engine even started). Today however, I noticed for the first time another symptom. When the car is placed on park and then back in drive, the transmission does not completely engage in 1st. It engages 1st on the first bit of gas I give it-did it while car was cold and hot. Never did that before, not even yesterday. It only does it when in P and then to D it does not do it when I come to a complete stop.
The mod valve was only changed. I had the red cap one and replaced by another red cap but no adjustments were made; also have not tested for vac leaks. Will go for the K1 kit, ATF and filter and revert.
Krgds,
Erick

[HATTENATOR]

After you change the K-1 kit I would check the modulator pressure and make sure it is set correctly since you have not adjusted your modulator. You can get the correct settings for your transmission here. http://www.benzworld.org/forums/w201...-problems.html This is a must do after a modulator change the modulator should be set corretly and not just randomly.

[Peavey]

I am having the same flare problem with my 94 500SL. I read through your article and I am pretty sure it is the same issue; my SL has a 722.5 transmission. However, I am having trouble finding this kit. Can you offer any suggestions?

Thanks!
Phil Vorwerk

[HATTENATOR]

Phil

You should be able to order this kit using the part number on the package from your local Mercedes dealer. I have not found anyone but Fastlane, online that has this listed but I know it can be purchased directly from the dealer. If you have any problems let me know



I have also added this link for mercedes shop fastlane they have it but I think you can get it from MB cheaper MercedesShop FastLane

[Kynyption]

Wierd, wonder why this didnt make its way to FAQ, oh well added now. Great help hattenator

[Peavey]

Thanks, I was able to get the part from Mercedes Shop. The mechanic who was trying to order this first told me it was a bad part number, then told me that it was backordered. Perhaps he copied down the part number incorrectly.....

By the way, thank you for posting such a well illustrated, detailed DIY procedure for this. I would tackle this myself if I had a rack; I'm just not into laying on my garage floor underneath my car anymore.

Thanks!
Phil