B2 transmission piston, small push rod fell out -- Pics included

17973 Views 31 Replies 12 Participants Last post by PrecisionHD, Nov 26, 2017

Jcom7777777

Discussion Starter · Apr 8, 2009

7

Hello everyone.

I have an issue that can hopefully be solved by this forum and its great members.

I will get right to the main issue. When the transmission filter was removed, a small push pin fell out. There was also rounded plastic chunks in the bottom of the tranny pan. I would like to determine what this pin is, what the plastic might have come from, and where the pin is supposed to be.

Now some background...

1992 300D 2.5 Turbo
722.4 Transmission
210,000 miles

While leaving from a stop, I began to accelerate. About 1 second later the car stopped accelerating. Upon shifting into 2, 3, and D no motion only engine reving. I was able to shift into reverse and backed the car home about a mile. I purchased the car about 6 months ago and it has been a daily driver with NO transmission issues whatsoever, until now.

I did some research and thought the B2 Piston might be the culprit. I have attached pictures of the B2 piston and the push pin that fell out.

Of the 2 pins in the picture, the SMALLER pin is the one that randomly fell. The other pin was securly in with the piston.

The piston is entact and not in 2 pieces, so I do not think the whole B2 Piston issue is the cause for my problem...the new issue is this random small pin/rod that fell when taking out the transmission filter.

Any advice would be greatly appreciated.
Happy Driving.

See less See more

1 - 20 of 32 Posts

mbtech124

· #2 · Apr 8, 2009

On the 722.4 the bands will break. But if the band is not broken you can reinstall this without removing the transmission. Remove the valve body and the intermediate plate with the rear smaller valve body from the transmission.
You want to get a longer adjustment pin for the one on the piston side. Put the small one back in first and then just reinstall the new longer pin and the piston. I almost forgot. You will have to remove the a plastic piece also that is pretty obvious once you get the intermediate plate off.
If the band is broken then the transmission must be removed.

Good luck.

Jcom7777777

Discussion Starter · #3 · Apr 9, 2009

Thank you for the info. A couple questions about your response:

Do you have any idea if the smaller pin butts up against plastic? I am wondering where the plastic chunks may have come from.

Also, If I was to get a longer pin in place of the piston pin, is this to take up space which was once occupied by the broken plastic?

Would a longer piston side pin cause misalignment?

mbtech124

· #4 · Apr 9, 2009

The short pin has a plastic retainer. It is not necessary except for installation.
The pins come in different sizes for adjustment purposes. The only concern is that you do not get it to tight. There still needs to be some play so the band is not engaged all the time. But these were normally so loose that you can get at least one size bigger on the adjustment pin.

Jcom7777777

Discussion Starter · #5 · Apr 13, 2009

I went to the dealership and purchased a new small pin, 2 longer pins of different sizes, and a spacer.

The longer pins came an about 5 different sizes. The short pin only came in one size. The spacer looks like it fits between the small pin and the brake band.

The parts cost $21.20 and should be here on Tuesday. I hope this solves the problem. Ill write a follow-up post when the job is complete.

Jcom7777777

Discussion Starter · #6 · May 23, 2009

Fixed

This is where the smaller pin fell out of. After installing all the new parts, the car is driving great. No problems. Thanks for the help guys, couldnt have done it without ya!

See less See more

BenzHell

· #7 · May 26, 2009

Need an easy tutorial

Hi there...I have run into the same problem and have started a thread on this issue where some of the good guys here are helping me out in diagnosing the problem. They said maybe this is the issue so I have been looking around and found this thread ...My Problem..:crybaby2:reverse ok but no drive,2,3,4 just revs. As I am going to attempt to see if the problem is the B2 with NO EXPERIENCE WHATSOEVER ON CARS...I would like to know would you happen to have a PICTURE tutorial with like step one and pic step two and pic step three and pic and so forth and so on....? Something that even a child could follow

I need it cause these guys in Japan are asking me between 3 to 6 g's to fix it. When hopefully it will cost under $100 and a few hours of gettin greasy elbows. All help is appreciated:bowdown:

Regards,

Christian AKA BenzHell

Jcom7777777

Discussion Starter · #8 · May 26, 2009

BenzHell,
I do not have any sort of picture tutorial. But I do have a pdf file that shows how to disassemble and reassemble the transmission valve body...BUT I will need to search for it and I am not home at the moment.

My car did the same problem, reverse worked - but no drive in any gears. I thought it was the B2 piston issue, but upon checking, it was not. The push pin was the culprit.

If you take the transmission mount off and push the transmission over to the side, you can access the b2 piston area. You will need to take off a snap ring then a cap. Then the piston will come out.

If you discover that the piston is still good, your problem is most likely the same issue I had. You will have to drain the transmission fluid, take the pan off, take out the filter, then take off the valve body. The whole time you should be looking for that push pin that might have fallen out. If you find the pin, go to the dealership and purchase a new small pin, the plastic spacer, and a new adjustment rod. The adjustment rod comes in multiple sizes. I cannot accuratly tell you what size to purchase, just get something larger than what you originally had.

That should do the trick. You might as well get a new transmission filter and seal while your at it.

Ill look for that pdf file.

Good Luck.

See less See more

Jayare

· #9 · May 27, 2009

Christian,

"NO EXPERIENCE WHATSOEVER ON CARS" wants me to advise you to find someone that does have experience. This is not like changing a flat tire and more than general knowledge of things mechanical is needed. This will be an open can of worms for you as a first car project. Really, find someone that is not out to screw you and pay for the job to be done. The monies you were quoted sound crazy to me.

Good Luck,

Jayare

csquared4290

· #10 · May 27, 2009

Oh snap...Jayare is back!!!!!

BenzHell

· #11 · May 27, 2009

Jcom7777777 said:
BenzHell,
I do not have any sort of picture tutorial. But I do have a pdf file that shows how to disassemble and reassemble the transmission valve body...BUT I will need to search for it and I am not home at the moment.

My car did the same problem, reverse worked - but no drive in any gears. I thought it was the B2 piston issue, but upon checking, it was not. The push pin was the culprit.

If you take the transmission mount off and push the transmission over to the side, you can access the b2 piston area. You will need to take off a snap ring then a cap. Then the piston will come out.

If you discover that the piston is still good, your problem is most likely the same issue I had. You will have to drain the transmission fluid, take the pan off, take out the filter, then take off the valve body. The whole time you should be looking for that push pin that might have fallen out. If you find the pin, go to the dealership and purchase a new small pin, the plastic spacer, and a new adjustment rod. The adjustment rod comes in multiple sizes. I cannot accuratly tell you what size to purchase, just get something larger than what you originally had.

That should do the trick. You might as well get a new transmission filter and seal while your at it.

Ill look for that pdf file.

Good Luck.

Thank you for your reply and help. I have just obtained a lot of information on this from Michael. I am going to take some time and read over the material and will get back to you guys with an update. I would like to take a look at that PDF since you could never have to much information:thumbsup: You can PM me or post here when you found it. Once again thanks for taking out the time to help.:bowdown:

Regards,

Christian AKA Benz Hell

BenzHell

· #12 · May 27, 2009

Jayare said:
Christian,

"NO EXPERIENCE WHATSOEVER ON CARS" wants me to advise you to find someone that does have experience. This is not like changing a flat tire and more than general knowledge of things mechanical is needed. This will be an open can of worms for you as a first car project. Really, find someone that is not out to screw you and pay for the job to be done. The monies you were quoted sound crazy to me.

Good Luck,

Jayare

Greatly appreciate your concern as I to am worried about doing this as a first project. Though it is a pretty big job, from looking at some information I have been provided and some pic tutorials I have found it seems quite doable. Here in Japan it is difficult, in Japan if its broken it's broken, which means I need a new one or a total overhaul. Or me being an American my add into the mix of things. Also it is difficult to find someone who can work on Benzs outside the Dealer. I mentioned before in my thread that since my car has been customized dealers in Japan will not touch it (its the new LAW), so it leaves me with no choice. Pay some idiot a ridiculous price to try and fix my car or pay a couple of hundred and get my elbows greasy. Even if I am 50% stupid it still leaves me with 50% smart

LOL..... maybe that's enough to get the job done

I am still going to do a lot more reading before attempting it....maybe this weekend or the next....I will keep you posted..or check out my thread if you like. I plan to put pics of the job up.

Thank you again for your concern and help.:bowdown:

Regards,

Christian AKA BenzHell

See less See more

mariyadas

· #13 · May 31, 2009

Could you please post the pdf instruction

Hi Christian,
I have the same problem on my 1989 Merc 190E.
could you please post the pdf and the way you fixed yours?
Thanks a lot.

BenzHell

· #14 · Jun 1, 2009

mariyadas said:
Hi Christian,
I have the same problem on my 1989 Merc 190E.
could you please post the pdf and the way you fixed yours?
Thanks a lot.

Hi there, I am sorry to say that I have still not received the PDF from 777777...
But I do have some material which Metafly provided me with as well as things I have found myself. If you PM me I can email it to you. If you like you can follow my progress on my thread here http://www.benzworld.org/forums/w202-c-class/1446797-first-fuel-pump-next-tranny-please.html

Today was actually the first day but did not get very far due to some bolts that would just not give.

Regards,

BenzHell:thumbsup:

BenzHell

· #15 · Jun 2, 2009

Jcom7777777 said:
.

If you discover that the piston is still good, your problem is most likely the same issue I had. You will have to drain the transmission fluid, take the pan off, take out the filter, then take off the valve body. The whole time you should be looking for that push pin that might have fallen out. If you find the pin, go to the dealership and purchase a new small pin, the plastic spacer, and a new adjustment rod. The adjustment rod comes in multiple sizes. I cannot accuratly tell you what size to purchase, just get something larger than what you originally had.

That should do the trick. You might as well get a new transmission filter and seal while your at it.

Ill look for that pdf file.

Good Luck.

Hi there,

So it looks like I may have the same problem as you, well so far. I found that same small pin on top of the tranny oil filter. Now I have been trying to take out the B2 pistons cover but for the dear life of me it will not come out. Been trying with little flat heads but when you get one side nearly out, the other side goes back in. Try to wiggle it and it all just goes in like its being sucked in..gues its the oil.....Any tips on how you got yours out...Everyone says it was a snap to take off but that bugger wont give

So if that is ok then it looks like I will only have to put the little pin back in. Though someone said..........
"If the band is broken then the transmission must be removed." What does it mean? What band?

Also what do you mean by "go to the dealership and purchase a new small pin, the plastic spacer, and a new adjustment rod. The adjustment rod comes in multiple sizes. "PLastic spacer? Adjustment rod? What are they and where do they go?

I appreciate your help and anyone else:bowdown:

Regards,

Christian AKA BenzHell

See less See more

bigwiki

· #16 · Jun 7, 2009

This is a good thread. I would like to know more. Keep it going.

BenzHell

· #17 · Jun 12, 2009

Jayare said:
Christian,

"NO EXPERIENCE WHATSOEVER ON CARS" wants me to advise you to find someone that does have experience. This is not like changing a flat tire and more than general knowledge of things mechanical is needed. This will be an open can of worms for you as a first car project. Really, find someone that is not out to screw you and pay for the job to be done. The monies you were quoted sound crazy to me.

Good Luck,

Jayare

"NO EXPERIENCE WHATSOEVER ON CARS" OPEN CAN OF WORMS???

Just wanted to let you know, I DID IT!

Regards,

Christian AKA BenzHell

Jayare

· #18 · Jun 12, 2009

Christian,

Your efforts make us all proud to be a part of this forum. Fantastic that you were able to do this at your experience level. Way to go partner and

Good Luck,

Jayare

BenzHell

· #19 · Jun 17, 2009

Jayare said:
Christian,

Your efforts make us all proud to be a part of this forum. Fantastic that you were able to do this at your experience level. Way to go partner and

Good Luck,

Jayare

Thank you for your words. If it had not been for guys like you giving advice and guidance, this would not have been possible. RESPECT and THANKS to this forum and all the guys here...including you

Good Luck to you too!

Regards,

Christian AKA BenzHell

timmyr

· #20 · Aug 17, 2009

hello to all,
i recently had the same issue with my car, loss of forward. upon droping the tranny oil pan and pulling the transmission fluid filter, i too found the small thrust pin on top of the filter. I purchased a new(longer) thrust pin for the b2 piston, plastic retainer for the smaller thrust pin and put her back together, and all is well... for now

.

I've read up on this particular issue on a ton of forums, and the funny thing is that no one has ever mentioned measuring b2 brake band travel...how did you guys manage to measure the b2 brake band travel? i found it to be a pain in the ass! due to the location of the b2 brake band. i happen to have a pretty big vernier caliper and still had no luck. i'd also like to mention that the accepted b2 brake band travel should be inbetween 5.5-6mm(according to the automatisches getriebe 722.3 e-book). I think that it would be very useful for the rest of the members if someone familiar with the procedure could elaborate a bit more on how to properly measure b2 brake band travel?

thanks to all for the useful info

tim

See less See more

1 - 20 of 32 Posts

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.