Failed B2 Piston install - PeachParts Mercedes-Benz Forum

gozapper · #1 03-26-2013, 12:58 AM

Failed B2 Piston install

I replaced the B2 Piston with the transmission in the car. Also replaced the sleeve and seal.

I did a three mile test drive and all seemed well, no leaks. I thought we were ready to start driving it again. I went to put fuel in and drove 2 miles and lost all the fluid. Got it towed back home and looked at the B2 cover. It was partly hanging out of the transmission. The snap ring was partly
still in place. I have a parts car with a good transmission that I want to install. I am wondering what could have caused this failure. I removed valve body so I could make sure the dog leg was where it should be.I thought the ring in place all the way around. I know the groove was clean where the ring goes..I suppose there couldn't enough pressure on the piston to do this.

What is the purpose of the tab with hole?

Any comments will be apprieciated

Thanks, Tom

Stretch · #2 03-26-2013, 04:10 AM

Strange - it does look to me like there's some sort of damage on the left hand side of the casing right next to the piston cover =>

Could it be as simple as you didn't push the piston all the way in - fit the cover - and then make sure that the ring was firmly in place?

When I fit these ring clips I usually push with a screw driver against one end of the wire (at the open end) so that the whole ring clip spins round in its slot.

cho · #3 03-26-2013, 04:44 AM

.
damage it is
picture is inverted!

lack of lubrication while positioning circlip or too much brute force
applied during removal of circlip.

.

Stretch · #4 03-26-2013, 11:35 AM

Quote:

Originally Posted by cho

.
...
picture is inverted!

...

Indeed you need to be an all position mechanic to work on an old Benz!

Diesel911 · #5 03-26-2013, 11:57 AM

I tuned the Pic right side up.

Take a good look where I circled there is a crack. It looks like the cracked area has been knocked in???

97 SL320 · #6 03-26-2013, 07:28 PM

There is a big portion of the trans casting gone around the servo cover. When the cover was removed, did you push the cover in to the trans ~ 3/8" then remove the snap ring? Same goes for install.

Also, the open end of the ring should not be located in the open portion of the snap ring groove. I'd have to match up the parts, but the tab / hole in the servo cover might be a area for the open portion of the snap ring. My thinking is that the solid portion of the snap ring was on top of the tab holding the cover sideways, a couple of shifts and the casting broke out.

The trans will have to come out and be replaced / trans case replaced.

vstech · #7 03-26-2013, 09:37 PM

yup, you're gonna need a new case

vstech · #8 03-26-2013, 10:00 PM

if you can't find one local, just let me know. I can get one stripped out and sent to you if you need it.

tbomachines · #9 03-26-2013, 10:03 PM

I can't tell if Diesel911 has the same thing circled, but on the bottom left of the housing there's definitely a crack. Bad news.

Diesel911 · #10 03-27-2013, 12:40 AM

Quote:

Originally Posted by tbomachines

I can't tell if Diesel911 has the same thing circled, but on the bottom left of the housing there's definitely a crack. Bad news.

I rotated the Picture so it was rightside up. So what is on the bottom of the POs pic is now on the top.

whunter · #11 03-27-2013, 02:48 AM

Quote:

Originally Posted by gozapper

Failed B2 Piston install

I replaced the B2 Piston with the transmission in the car. Also replaced the sleeve and seal.

I did a three mile test drive and all seemed well, no leaks. I thought we were ready to start driving it again. I went to put fuel in and drove 2 miles and lost all the fluid. Got it towed back home and looked at the B2 cover. It was partly hanging out of the transmission. The snap ring was partly
still in place. I have a parts car with a good transmission that I want to install. I am wondering what could have caused this failure. I removed valve body so I could make sure the dog leg was where it should be.I thought the ring in place all the way around. I know the groove was clean where the ring goes..I suppose there couldn't enough pressure on the piston to do this.

What is the purpose of the tab with hole?

Any comments will be appreciated

Thanks, Tom

What year and model is this on?

Unfortunately the "transmission case snap ring lip" is broken away.

It may have been weak from previous road damage.
At this point, knowing the exact reason for the break is no help to you.

The transmission or case needs to be replaced.

.

gozapper · #12 03-28-2013, 01:09 AM

I want to thank all for their interest on this.

I figured out what caused the failure today while removing the seal that holds the sleeve in place.

I was looking at how to remove the seal and trying to figure out how to pry the seal with a long screw driver, but to do this the srew driver would put pressure against the part of the meat that the lock ring fits in. Then I remenbered trying to use this techniqe to remove the seal while transmission was in the vehicle. Back then I finnally removed the valve body to punch out the sleeve and seal fron inside the case.

I discovered this because I wanted to use the new piston in the doner transmission. This time I made a puller using the bolt and washer ground down on the sides so it would slip through the seal and a bolt thrugh a bar across the top of the opening. This was a challange even with the trans out of the car laying on it's side. But next time I think I could do in in the vehicle.

I have 3 new pictures to show the differnce between the old and new styles B2 Pistons Left one is the old style, one on right in new style.

Thanks for all the interest in my screw up. Maybe this could someone later doing this.

Tom

Diesel911 · #13 03-28-2013, 11:58 AM

Quote:

Originally Posted by gozapper

I want to thank all for their interest on this.

I figured out what caused the failure today while removing the seal that holds the sleeve in place.

I was looking at how to remove the seal and trying to figure out how to pry the seal with a long screw driver, but to do this the srew driver would put pressure against the part of the meat that the lock ring fits in. Then I remenbered trying to use this techniqe to remove the seal while transmission was in the vehicle. Back then I finnally removed the valve body to punch out the sleeve and seal fron inside the case.

I discovered this because I wanted to use the new piston in the doner transmission. This time I made a puller using the bolt and washer ground down on the sides so it would slip through the seal and a bolt thrugh a bar across the top of the opening. This was a challange even with the trans out of the car laying on it's side. But next time I think I could do in in the vehicle.

I have 3 new pictures to show the differnce between the old and new styles B2 Pistons Left one is the old style, one on right in new style.

Thanks for all the interest in my screw up. Maybe this could someone later doing this.

Tom

Pics from a Member over on Benz World. I posted a simple drawing on how to make the Tool on Benz Worked and the Guy made it and you can see the results.
I believe the cross piece is from a Gear Puller rented from Autozone but can't remember what he said.
If you do this use a thicker Washer as the one they Guy used bent.

I at first tried to use that tool as a Slide Hammer but found there was no room under the Car to do that.
So I used part of one of My Gear Pullers as the cross Piece.
The last pic is mine with out the cross piece.

vstech · #14 03-28-2013, 11:59 AM

the snap ring is actually quite easy to remove... but you have to press in on the cover first to release pressure on the ring. then a simple pic or small screwdriver will slip it out.