Grrrr!!! What did I do wrong!!??? Huge leak from TC housing after trans swap!!
 

Spent a week laying under my car in the rain taking the broken 722.4 out of my 300td and installing a "new to me" 722.3 only to find out I did something wrong or the "new to me" trans is faulty. Pretty much meaning I have to re do the whole job...


So after fit up there is pretty big leak coming out of the bottom of the torque converter housing. See pics and video.

The leak in the video is about a drip a second, after adding 6 qrts of atf, added another 3/4 of a qrt and it turned into a steady stream. Dont know if that is because I added more atf or because the car has been running for 5 mins longer.

<iframe src="https://player.vimeo.com/video/508157453" width="640" height="1138" frameborder="0" allow="autoplay; fullscreen; picture-in-picture" allowfullscreen></iframe>
<p><a href="https://vimeo.com/508157453">VID_20210203_131257783</a> from <a href="https://vimeo.com/user131134977">Aliyah Bellert</a> on <a href="https://vimeo.com">Vimeo</a>.</p>

https://i.ibb.co/crqYr2B/IMG-20210203-131325037.jpg

Here are the bullet points as to why I think I may have caused this problem.

I installed a new TC Seal. As far as I can tell it seated flat and a should work. But maybe I didnt push it is far enough or it wasn't seated properly. I did not use a press or a special "seal pusher" just gently pressed it in with small rubber malet lightly. PLEEASE SEE PIC AND SEE IF THE SEAL LOOKS OUT OF PLACE

The TC did not slide into place as easily the TC that I was in the old trans that I took out. (the TC out of the old trans was a 722.4 which is not compatible with the 722.3 I installed) Again I believe that it did slide into place correctly. I pressed it in and turned it until it slid in deeper and it felt locked in.

https://i.ibb.co/QXbpDpv/IMG-20210125-124016276.jpg

This TC that came with my trans is orange, Ive never seen one that isnt just rust color. I believe the basic part number was mx-10 or something. You can see it written in sharpie by the PO in the pic. I can confirm this a Mercedes TC, just cant confirm it is the correct one for this trans.

https://i.ibb.co/HD9FmSV/IMG-20210125-114345028.jpg

My concern is that the guy who sold it to me didnt have the TC so he bought one online or something that may not be correct. DOES THIS TC LOOK FAMILIER TO ANYONE?

After tightening up the bell housing bolts it just seemed a lot harder to turn the engine by hand then it did with the old trans installed. Making me worry the TC was not seated all the way thus applying a lot of pressure to the flywheel. Maybe I am just overthinking it when it comes to this one.

Lastly before I noticed the leak and when I was re filling with atf I had the car up and stands and was running thru the gears but i forgot to put my foot on the brake and went from drive to park. I got the click click click sound for a few seconds and then it stopped. Ive done this before with cars on accident while drive 30 mph and no problem was caused but not sure about this car.


Does anyone have any input on was causes a leak like this?

Does anyone have any input on what I should look for to fix it?

Could this be a bigger issue than just a improper seal or TC seat?

PLEASE SEE PIC AND SEE IF THE SEAL LOOKS OUT OF PLACE

Looks in place, sometimes the spring inside the seal can jump out while being hammered in. Pack the back of the seal lightly with grease or Vaseline to prevent this. Check the fit of the new seal on the torque converter neck before install.

The TC did not slide into place as easily the TC that I was in the old trans that I took out. (the TC out of the old trans was a 722.4 which is not compatible with the 722.3 I installed) Again I believe that it did slide into place correctly. I pressed it in and turned it until it slid in deeper and it felt locked in.

The converter must jump backwards twice while being rotated to be seated.

After tightening up the bell housing bolts it just seemed a lot harder to turn the engine by hand then it did with the old trans installed. Making me worry the TC was not seated all the way thus applying a lot of pressure to the flywheel. Maybe I am just overthinking it when it comes to this one.

Your not overthinking this it sounds like the converter may not have been seated.

Lastly before I noticed the leak and when I was re filling with atf I had the car up and stands and was running thru the gears but i forgot to put my foot on the brake and went from drive to park. I got the click click click sound for a few seconds and then it stopped. Ive done this before with cars on accident while drive 30 mph and no problem was caused but not sure about this car.

You probably didn't hurt anything.

Could this be a bigger issue than just a improper seal or TC seat?

No other than a bad front pump bushing or scoring on the neck of the converter.

Are you certain it isn't the converter drain plug leaking?

thank you for the response. I'm not sure if I got the double jump when I installed the tc. and also don't know why I didn't think of checking the seal to the neck of the converter before Installed it.

I know it will be kinda difficult but could you try to explain how the TV will jump back 2 times? I understand how it will click into those little notches that are on the TC shaft but how does it's jump in a second time?

I remember one night before. I started the install and was trying to check the OD of the TC vs the ID of the transmission input but I couldn't fit the calipers inside the bell and got a case of the "F it's"

i really think I just didn't seat the TC all the way. Now that I think about it I had to remove that plastic plug that stops the TC from falling out during install because the TC wouldn't spin freely (yes I turned it so the crooked part was facing out) This should have been a bigger red flag then I assumed it was in hind site.

Well live and learn I'm sure doing the job a second time will go 5 times faster now that I've figured out all the tricks and what order of doing things is the best.

I'll update once I get it pulled and inspect the TC seating.

And yes I did check to see if was as simple as the drain plug leaking. it wasn't that. New plug me crush washer torqued to spec as well

I have no good advice to offer but I will be watching this thread. I know that feeling of spending hours in onerous conditions, hoping for that glorious payout that somehow eludes you at the end. Damn that can be deflating.

Compare the front centering noses of the converters to confirm that they are same and that they both fit into the back end of the crankshaft.

Good luck!!!

If the leak occurs only with the motor running that would say the seating of the Torque convertor is suspect. As that is when the transmission pump fills the TC with fluid. That is why you check fluid level with the motor running.

If it leaked when just sitting then I would look toward dipstick holder and pan for leaks.

The front centering noses are different. I think they were the same diameter but the orange one is a bit longer than the old trans. maybe 1/4" - 1/2"

I just figured that nose would slip further into the crankshaft hole.

It just seems odd to me that none of the oil is coming out of the hole/vent that you use to unscrew the drain plug of the TC. The leak only comes out of the seam between the engine and bell housing and that is on the opposite side of the TC.

I would think at least some of it would be dripping out of the drain plug access hole.

Gonna be interesting to see what I find when I drop it today.


And ya it only leaks when it's running.

If you were able to batten down the torque converter flush to the mount by tightening down all the bolts through the window at the back of the engine then the nose should not be a factor. A longshot were you able to fully secure all the bell housing bolts?

ya I got them all torqued to spec. but after tightening them I could only turn the engine by the main crankshaft bolt on the engine. turning it with the power steering bolt was nearly impossible, it just felt extremely tight. I've always turned the engine by hand with ps bolt and pulling on the belt. the starter didn't have a problem cranking the engine or anything like that tho.

one thing I remember now is this, when I first started tightening the bell housing bolts I started from the bottom and tried to pull it together with an impact. At two separate occasions during this process I heard a sharp metal "ping" I assumed it was the two "alignment knubs" on the bell housing that were popping into place or the center alignment nub on the TV seating into the engine.. although on second thought it defentily resembled a sound of something metal either breaking or popping into or out of place.

After I this method of bolt up wasn't working I took all the bolts out, adjusted my jack on the transmission and started bolting down from the top. This made it so I didn't have to suck anything together with the bolts, everything was pretty close to lined up and the sound never happened again.

it's raining outside again and trying to get the drive to get under the car and get over this discouraged feeling I have. Hope to get going sometime today and get se. answers.

Thanks for the input guys

Suggestions...

Pull the transmission and look for obvious problems e.g., cracks and inspect the front pump for damage. I do not want to bring bad news but the front pump may be damaged. If you have a local transmission shop they may be willing to pull the pump and inspect, it isn't difficult.

Take the converter currently in use and see if it goes flush against the flexplate, if not figure out why. Is the nose too long, too wide or does it have a burr on it?

Put the transmission up without the converter, it should easily go flush to the block. It may help on the install if you get threaded rod or bolts of the same thread, cut off the heads thread them into the block and use them as alignment dowels. Take the trans back out.

Replace the front seal, put the converter in the trans spinning it and pushing it backwards until it jumps back twice, install the trans and it should go flush to the block just as it did without the converter. Bolts are not needed and should never be used to draw it into place. Sometimes it easier to stand the trans on its tail to get the converter seated.

Good luck!!!

The two jumps are one as the splines on the center shaft engage into the converter and the second one is when the two slotted ears on the converter neck engage the pump. Each "jump" will be a slight (1/4") movement back toward the transmission.

Good info Sugar Bear.

You guys wanna know what happens when u don't seat the TC properly and try to torque it down to the fly wheel??? u break it.

the two drive nubs on that are in the transmission side were snapped off.

I believe this happened when I thought the TC was seated and torqued the bell housing down, this is when I heard two pops.

Here is the damage. the two broken nubs and in the last pic you can see what seems to be a hole.

https://i.ibb.co/k3Pz1xt/IMG-20210204-170820352.jpg
https://i.ibb.co/hCkmj7p/IMG-20210204-171037678.jpg
https://i.ibb.co/Cz3Dmdx/IMG-20210204-171247276.jpg

This for sure couldn't have happened from me putting the car in park from drive?? It's just really odd I could miss something so obvious and not seat that TC down. But I def remember having issues with with clearance of that plastic retainer nub and said **** it.

damn I feel stupid. its a learning experience tho.
Took me about 8 hours at least to pull it the first time this time I had it dropped in an hour.

So what's my next step? can this part be replaced? Can I just pull this whole front section off my old trans and swap it over here?

That is a shame, but it could have been worse if the pieces got into the trans.

Does the NSS switch even work if it's not plugged in up at the cluster? that's where the end of that harness goes correct??