denichristantra

Hi folks,

Anyone ever tried to do this before? I have 5th gear issue, it wont engage. Here is what i did to solve the problem :

1. Gear Selector checked (I have replaced the white tooth that connects the metal plates on "D")
2. HGS Unit replaced
3. Throttle Position Sensor checked
4. 5th Gear Solenoid in the valve body checked and in good condition
5. The electrical cables to the 5th Gear Solenoid and Kickdown Solenoid checked. Good flow.
6. Scanned the car, no fault codes.

Therefore, I'm quite sure the problem is not electrical. So, after i did all the above, i started looking at hydraulical problems. And here's what i did :

1. Modulator Transmission checked. Adjusted to 4,0 bar as specified in WIS
2. Control Pressure Cable (Bowden Cable) checked.
3. Upshift Delay checked (Replaced the hoses)
4. Disassembled the Valve Body, replaced the O rings, cleaned it thoroughly.
5. Springs checked, no damage, no broken spring in the Valve Body.
6. ATF flushed both in the Transmission and Torque Converter.
7. The ATF filling procedure checked. Dipstick checked both in cold (30 C) and in warm (80 C).

And the problem persists. I thought i have done everything that could possibly be done, until i remember i haven't checked the spools and the bores in the Valve Body. So i did. I tore it down again, finding play between spools and the bores..... i couldn't find any.

Reread WIS, and found that the valve spools responsible for 5th gear are not in the main valve body, but in the bottom cover or lower cover/auxiliary valve body. They are Valve Spool #101 and #100. So I tore the bottom cover down, and found 0,5 mm play in both spools. Was happy. Brought them to CNC Lathe workshop only to find that they didn't know the material used to make the spools. Looking at the appearance, they thought the spools were made from steel carbon.

Anyway, i bought steel carbon round bar, brought it to them. Waited for 10 days, took the new spools, put them in the bottom cover, and found 0,3 play in both of them.

At this point i was a bit desperate, more desperate when i dig deeper, i found that the max tolerance of play between a spool and a bore is only 0,005 mm.

So i brought them to another CNC lathe workshop, possibly the best in my city, and they said something a bit shocking. They said, even if they can make the spools correctly and fit the bores, there is no guarantee that the bores in my bottom cover is still symmetrical. They told me to buy a new bottom cover and gave up even before they touch my steel carbon bar.

Went home, browsed the internet for new valve body assembly and bottom cover with zero result. The part number is one of the rarest there is. So i went to buy a complete used 722.509 transmission in local Mercedes junkyards, and found none. They have 722.3, 722,4, 722.6, 722.9, but no 722.5 (Not even a broken one).

Anyway.... here i am, desperate, frustrated, and upset. I still believe that a good CNC lathe machine and a good lathe operator can fix this problem. Now i am thinking to buy a lathe machine and learn to create the spools myself, but it will be too much work and too much money spent.

So what to do guys? Maybe i missed something in the process? What will you do if you were in my position?

NOTE : All the gears other than 5th are present, smooth, and perfect.

Plutoe

Great third world solution. You should also post your solution on the iranauto.com.

kajtek1

Don't listen to clowns on this forum.
Go to benzworld and read or contact MAVA. He rebuilds those transmissions and is great forum contributor.

denichristantra

Thank you Kajtek1, i'll do that.

denichristantra

Heay, just wanna update the situation for people with the same problem who read this in the future.

It works. A good lathe operator and cheap alumunium round bar fix spool problem in the valve body.

My 5th gear works perfectly now. 30 dollar for the lathe guy, 20 dollar for the alumunium bar.