Transmission MYTH solved forever!!!!! GREAT RESULTS!!!

[kamil]

Hey...

Well if you have been following many threads lately you noticed that I have been posting about fixing my transmission hard shifts on the 240D. We have engaged in a conversation about the 3/2 valve on top of the valve cover. Many said that it does not control the transmission at all and some have claimed that it does. I opened the little black box on top and I noticed that I had two of those valves. I attached the MITY VAC and one was leaking BAD. I decided to change the locations on each one meaning I basically switched their spots. I didn't think anything would come out of it but let me tell you..... "The transmission shifts like BUTTER, I cannot even tell when it is shifting." If you are having bad problems with your transmission please do yourself a favor and check these valves. As a matter of fact I still need to purchase one since I just rotated them and that means that one is still bad. I have pics from my other threads to show exactly what I am talking about.. I even found a great price on the valve for about 25 bucks.

I just want to thank everyone that has helped me through my numerous threads. I know I ask alot of questions but you cannot learn if you don't ask. Thanks again for your help. I would not own a diesel BENZ if it wasn't for this site.

PS. I really cannot tell that my car is shifting. It is AWESOME.

Here is the pic of where the two little valves are located....



Here is a pic I found on the internet to show you what the valve looks like...mine wasn't this yellow but it was white instead

[rs899]

I am sure someone will correct me if I am wrong ( and someone will probably correct me if I am right as well), but the purpose of the switchover valves on top of the valve cover is related to EGR valve function( at least on my 300D it is). If somehow one knew that one's EGR valve was non-functional then there would be no point in having that mess on top of the valve cover.

I bypassed those valves and just went from the front port of the vac pump to brake booster line straight to the vacuum control valve and after a lot of fiddling , got my tranny to work acceptably.

Rick

[kamil]

mine had instant results though... and here is a copy and paste from FASTLANE as to what the 3/2 valve does....

Note: 3/2 way : White Plastic
Mounted on valve cover. Cam lever operated by linkage. Controls EGR, injection pump and automatic transmission via vacuum routing combinations

this is straight from Fast Lane's site

Rick,

I did the same thing. My EGR valve leaks anyways - so I just plugged the vacuum line that goes to the 3/2 valves. It's one less thing to worry about with transmission tuning.

[Brian Carlton]

We had a very good discussion going on this exact topic. DMorrison had explained the entire situation in the thread and then the thread disappeared right at the changeover.

I had questioned him regarding those valves becasue I was quite sure that the valves were only used for EGR on the 617. There is no routing of any lines back to the transmission vacuum shift valve on the 617.

However, he explained that the 616 absolutely does utilize one of those valves for the transmission and the other valve for the EGR. He posted some excellent vacuum diagrams as well.

So, I believe, based upon his comments, that the 616 uses one valve to control the transmission shifts and the 617 does not.

So, Kamil, you can just plug the valve that is utilized for the EGR and save yourself the cost of a new valve.

[redbaronph123]

i dont have (at least i dont see it) that on top of my engine...

[MTUpower]

Originally Posted by kamil

Hey... I have pics from my other threads to show exactly what I am talking about.. I even found a great price on the valve for about 25 bucks.

I [/IMG]

Those valves cost how much???? I'll go to the local yard and pull five of them for you for a $5.05 each- that's five bucks for pulling them, a nickel for the valve.

[Brian Carlton]

That would be worth it. Odds are that three of them are bad, but so what? You got two good ones for $5.00

[MBDFahrer]

Am I the only one that is evil enough to rip off the U-Pick parts junkyard with a 5 finger discount?

[dmorrison]

When getting a used airswitch suck on one opening and block the other with your finger. If air comes thru the metal shaft area the switch is no good. This leak will allow air into the vacuum system and mess with what ever your running.

Dave

[Mercedes Man]

Can someone explain why some engines have 3/2 valves and others don't?

Also, I always thought that you were supposed to feel the transmission shifting in a Mercedes.

[kamil]

Originally Posted by Mercedes Man

Can someone explain why some engines have 3/2 valves and others don't?

Also, I always thought that you were supposed to feel the transmission shifting in a Mercedes.

I'm also curious as to why some people claim that they only have one valve.

I always thought the same thing about the transmission making you feel every shift. It just kept getting worse and worse so I decided to tackle the problem somewhere. I literally don't feel any type of shifts (basically you can tell when the car is shifting by the engine sound)

[Pete Burton]

If the shift is very soft and you don't feel it and the engine RPM goes up slightly between shifts that isn't a good thing. That would indicate flaring or slipping in the trans clutch packs. If it shifts without raising the RPM between shifts, that's great, don't touch it.

[kamil]

Originally Posted by Pete Burton

If the shift is very soft and you don't feel it and the engine RPM goes up slightly between shifts that isn't a good thing. That would indicate flaring or slipping in the trans clutch packs. If it shifts without raising the RPM between shifts, that's great, don't touch it.

no raising RPM

[MTUpower]

Originally Posted by kamil

I'm also curious as to why some people claim that they only have one valve.

Because some do have one valve. My '80 TD has ONE.