Just getting a new to me 08 gl320 on the road. The change into 2nd is rough. Probably worse going 1-2. But also obvious 3-2.

according to the service book it has been 140,000km since last transmission service but I thought before I did service I would see if there is any feedback on the problem I am having

I have had 3 other 722.9 transmissions and this one is definitely unusual in this regards

probably slight flare in revs when it happens. Was thinking it would be worthwhile checking valve body when I did service

probably more noticeable on light throttle. Full throttle more typical to other 722.9’s ( always notice changes on hard throttle)

any thoughts appreciated

no codes present. Car has 210,000km

 

Think the cheapest thing you can do is at least get new and proper fluid in there… And see if that behavior continues then it’s very likely a valve body issue. Anecdotally; I’ve had 3 7gees myself, and the one that acted up the most was behind an OM 642 motor.

 

All the 722.9’s I have had are behind om642’s

probably the low down torque of diesel is bad for transmission

I think I will clean valves/valve body at least. Just wondering if there was something else to do when I was in there-that could be cause

 

I am quite familiar with the 722.9 tranny rough shifting.
First I would pull all the codes on the transmission . Post them here . If there are NO codes I would drop the pan and hopefully you have a torque converter drain bolt. Than drop the valve body and pull the solenoid valves and replace all the Orings. They are not easy to find but with some searching you should be able to get all 16 Orings. The smaller blue ones are usually the culprits.
If you have some speed sensor errors you will have to get the sensors replaced on the conductor plate or do it yourself. Make sure you watch some youtube videos on dropping the valve body and be careful with the electrical connector.
OK good luck and let us know if you have any codes

 

Many thanks, will do - have dropped the valve body before - taking care with shift rod and the input plug by memory - swapped two transmissions and used old valve bodies -

no codes present

Only historical was a speed sensor at about 150,000km ago so assume it would have been from low battery

will report back

 

sensors can cause the hard downshifts. Definitely pull the solenoids and mark them.. out them back in the exact same place.. I use a egg carton to separate and mark them. Clean the screens with a magnet. If the fluid looks really dirty I would pull out the 14 shift spools and clean them and check for broken springs etc…. if you find cracked or missing Orings that will be your problem and no need to dig thru more.

 

Hopefully I find a broken o ring. Are they green or black?

You are a man of my own thoughts. Use egg cartons heaps. Can write on the flap where everything is from if it is something that will be waiting on parts. and keep dust out anyway

i do have a low km valve body I can raid for springs etc if needed.

makes sense on the o ring as when revs raise the pump will produce more flow and reduce the symptoms of o ring failure.

 

What country are you in? My 2008 GL550 had blues on the bottom and black on top. I replaced with FKM V75… both top and bottom.
My son has a large R129 parts business and sells a lot on ebay. I am going to put packages together and sell them on ebay . I found it very hard to find in stock anywhere. MB will only sell the solenoids with Orings. If you are within my shipping area I should have my first big order this week. I will be selling the 16 Orings and 2 orange for the electrical plug for $25 USA plus shipping . Let me know if I can help you.

 

I am in Australia. I will let you know when I open it and have a look. Many thanks for offer. I am in a regional area so it is often hard to get parts. But delay to get from USA will be poor. Last shipment of parts took nearly 3 weeks.

 

Ok start looking around where you can order Viton metric Orings in Australia. Send me a private message ok once you drop the valve body and include some pictures. You should be able to feel the solenoids coming out how tight or loose they are. From my experience the bottom Orings flatten out .

 

Many thanks. Will do

 

Can you buy Amsoil in Australia? If yes get 2.5 gallons of Signature fluid .. best I have ever used. Put 45k miles and fluid still looked like new and valve body was spotless.

 

I will keep my eye out but I have got a heap of Fuchs titan. 4134.

 

make sure you check the specs on the Orings for transmission fluid and temp range.

 

Just pulled the valve body out. Everything looks quite ok but we notice that two of the yellow plastic spring loaded check valves are missing

has anyone seen this before. Seems to relate to k1 and b3 regulating valves



The circled valves are missing.

 

Did you find them in the sump or filter?

my guess would be a tsb for removing them.

 

There is no sign of them. Don’t think they were ever there. Have seen other people list same issue. Like never there.

no debris anywhere

 

WOW that’s a new one to me? Did you pull the solenoids ? How tight did they feel going in and out? Blue Orings at the bottom all intact? Also what is the part number on your valve body ? 220 270 1906?

 

Did you check all 18 shift spools and springs ? make sure nothing is stuck or broken springs ?

 

I don’t know if they ship to Australia?
https://cobratransmission.com/722.9-Valve-Body-Sub-Kit
Also I just read this page recently and wish I would have cleaned this screen. A new screen is included in Cobra’s kit along with the check valves. You can buy the solenoid Orings from them also.

 

Thanks for the attachment. I was not aware of that mesh strainer.

You are right. The smaller blue o rings on the solenoids were flattened off.

I have a set of o rings from an Australian transmission parts supplier in Melbourne.

I have read on the internet about others finding certain yellow plastic valves missing. Seems weird but there you go. I do have another valve body I could rob them from but we have decided to put it back together cleaned with new o rings. Flui. Filter Do an adaptation and see if improves

I cut the old filter open and there is no debris. Definitely not enough for the two valves

We did check operation of the valves no broken springs.

 

Where does one get documentation on how to work on these transmissions? The only thing that's stopped me from working on transmissions before is a lack of documentation.

 

There is quite a bit out there you have to google 722.9 and look for the manuals tips etc. I will try and include one that I like.

 

Here is more 722.9 info

 

More info
Solenoids for the 722.9
Remember to use a magnet to clean the screens and the well area where they sit.. after removing them. Mark and replace then in the same slot. I use an egg crate to hold them and mark.