Got stranded yesterday need advice - PeachParts Mercedes-Benz Forum

yuke · #1 07-06-2016, 08:17 AM

Was a bad day yesterday as I traveled 700 miles to visit my 92 yr. old mother I was there about a week and when I was returning home from pa. I had to pay a bill about 7 miles from my mothers house the ran fine and shifted thru the 4 speed auto. trans. smoothly, when I went to leave 5 min. later the car would not move at all in any gear it was almost like the driveshaft was unhooked but it did hold in park like it should. When I would put it in gear I could hear a little movement it seemed in the driveshaft but would not move an inch in forward or reverse. I checked the trans. fluid it was a little low I added a qt. but it made no change at all. I had to rent a u-haul truck and trailer and trailered it home because I have to go to work on Thurs. Does any one have any ideas as what could have happened and gave me no forewarning to leave me stranded? I still have the car on a trailer so I could take it to a trans. shop if needed. I do'nt know if I want to spend $2-3 grand to rebuild it. The car is an 85 (300)SD I think it has the 722.3 auto. trans. I heard some people talk about a nut that can work itself off at the rear of the trans. that would leave the driveshaft in limbo but I do'nt think it would hold in park like it does? I also heard people talk about a B-2 piston could that be my problem if so where is it and is it hard to change?

greazzer · #2 07-06-2016, 09:27 AM

My first MB, 85 300TD had that funky little nut come loose circa 2008. I was buzzing along on the interstate and then nada ... I was getting ready to pull the drivetrain until Phil (R.I.P.) called me around 11PM to inspect and test for that nut. Turned out that call saved me a really long, miserable weekend. Nut was around $5 bucks shipped. You'll need a 12pt 30mm socket in the event it's that.

pimpernell · #3 07-06-2016, 09:28 AM

Quote:

Originally Posted by yuke

Was a bad day yesterday as I traveled 700 miles to visit my 92 yr. old mother I was there about a week and when I was returning home from pa. I had to pay a bill about 7 miles from my mothers house the ran fine and shifted thru the 4 speed auto. trans. smoothly, when I went to leave 5 min. later the car would not move at all in any gear it was almost like the driveshaft was unhooked but it did hold in park like it should. When I would put it in gear I could hear a little movement it seemed in the driveshaft but would not move an inch in forward or reverse. I checked the trans. fluid it was a little low I added a qt. but it made no change at all. I had to rent a u-haul truck and trailer and trailered it home because I have to go to work on Thurs. Does any one have any ideas as what could have happened and gave me no forewarning to leave me stranded? I still have the car on a trailer so I could take it to a trans. shop if needed. I do'nt know if I want to spend $2-3 grand to rebuild it. The car is an 85 (300)SD I think it has the 722.3 auto. trans. I heard some people talk about a nut that can work itself off at the rear of the trans. that would leave the driveshaft in limbo but I do'nt think it would hold in park like it does? I also heard people talk about a B-2 piston could that be my problem if so where is it and is it hard to change?

Please understand that I do not recall the year or model of my older mercedes,but the "nut" that you describe was the cause of my car acting the same way. It was a "lock nut" that holds the "band adjustment" setting in the tranny. It had worked itself loose, and the bands were slipping, and the car would go nowhere. The band adjustment screw was reset, locknut tightened, and I was on my way as if no time at all. Hope this is the same in your case.

yuke · #4 07-06-2016, 10:10 AM

Greazzer to inspect that nut do you have to drop the whole driveshaft or just the front? That was my 1st guess as what happened. Would your car still lock in park and not roll when that nut came off? Im hoping that is what is wrong with mine. Were you able to fix it right where you were at?

leathermang · #5 07-06-2016, 11:06 AM

I would guess that the adjustment lock nut will be on the side of the trans...
and hopefully NOT require pulling the driveshaft...
but I do not know for sure..

pimpernell · #6 07-06-2016, 11:15 AM

Quote:

Originally Posted by yuke

Greazzer to inspect that nut do you have to drop the whole driveshaft or just the front? That was my 1st guess as what happened. Would your car still lock in park and not roll when that nut came off? Im hoping that is what is wrong with mine. Were you able to fix it right where you were at?

It was located on the side of the transmission as another poster stated.

https://**************.com/problems/transmission/1968-1981-automatic-transmission-wont-go-or-slips-badly-reverse

greazzer · #7 07-06-2016, 11:36 AM

Quote:

Originally Posted by yuke

Greazzer to inspect that nut do you have to drop the whole driveshaft or just the front? That was my 1st guess as what happened. Would your car still lock in park and not roll when that nut came off? Im hoping that is what is wrong with mine. Were you able to fix it right where you were at?

This sounds horrible, but I don't recall doing any of that. I think I jacked up the rear and turned the rear tires by hand and noticed the DS just spinned (I think). Whatever I did, I did it in around 5-10 minutes, and you can see where the nut came loose and the yoke was not engaged on the splined shaft. I had zero before hand symptoms. Car ran strong and then nada ...

greazzer · #8 07-06-2016, 11:41 AM

here's some pics of what you're looking at ...

t walgamuth · #9 07-06-2016, 11:44 AM

Did you check the fluid level?

yuke · #10 07-06-2016, 12:36 PM

Yes I checked the fluid level it was a little low but it did read on the stick so for good measure I put a qt. In and there was no difference. My only thought was that if it is the nut on the tail shaft that I would think it would not lock in park but mine locks very solid we even rolled it a little and I put it in park and it stopped the car abruptly. The way I understand is there is a nut on the inside of the output shaft which is hard to get at and there is one on the outside of the shaft where it connects to the flange whkch is the easier one to get at and could be the problem as in greazzers case. I dont know where the other nut that keeps the bands tight is at but I will get under there and take a very close look. If the nut did loosen up I hope the splines didnt get ruined. The car is on a trailer right now with the middle cut out only metal where the wheels go so that might give me some good clearance under there that I wont have to jack and block it up.

leathermang · #11 07-06-2016, 12:45 PM

Quote:

Originally Posted by yuke

Yes I checked the fluid level it was a little low but it did read on the stick so for good measure I put a qt. .......

Ok.. I know this was under duress... etc.....
but as soon as you can you need to adjust the trans fluid level to the correct level..

OVERFILLING can , just like with oil in your engine, cause FOAMING... which introduces oxygen into the fluid quickly taking away its ability to function normally AND depositing varnish in place it should not be.

snapped_bolt · #12 07-06-2016, 12:56 PM

Hi,

I had the same symptoms, started car while doing errands, put it and gear and sudden nothing- no forward, no reverse.
I suppose you could test by having a helper step on the brake while you crack a trans cooler line on the radiator- a pressurized leak would indicate the front pump is working.
No pressure- no go. The drive tangs could be broken on the torque converter, or the splines in the front planetary gear set could be stripped.
When mine failed, there wasn't so much as a "click" to tell me anything could be wrong. It was almost as if the transmission had been stolen while I was in the store.
No other symptoms of impending failure preceded this.

snapped_bolt

yuke · #13 07-06-2016, 02:14 PM

I just was under the car and looked very closely at the rear of the trans shaft everything looks good there so if it is a spline or tang it seems like you would not be able to see it unless you ripped it apart. I looked for a nut on the side of the trans but I guess unless you knew what you are looking for you wont see it. It would be good to establish if there is pressure like snapped bolt suggested I was wondering snapped bolt did you ever establish exactly what failed on yours and how did you repair it? I imagine it would be much cheaped to find a good used one rather then rebuilding the trans.any one close to N.W. In. have one?

leathermang · #14 07-06-2016, 02:24 PM

YUKE,
' establish pressure ' is in line ....
WEAR GOGGLES....

snapped_bolt · #15 07-06-2016, 02:33 PM

I replaced it with a used one. I got lucky up here, it showed up on Craigslist a few days after mine died.
I still have the transmission that died. I removed the bell housing and found damage behind the front pump, three distorted Philips head screws (2 in the pan); the splines on the front planetary were stripped.

Link to new thread with the pictures of damage-

722.117 Failure mode

The pan was surprisingly clean, I theorize a PO had some work done on it, but the Philips screws had NOT been installed with Loctite. I do not know if they were part of the failure or the splines in the planetary would have stripped or not.
I am going to replace the front planetary along with the damaged parts with good used parts. It's somewhere on the "long list"! The bell housing gasket along with the front pump seal should be replaced at the same time.
I have a recent quote from some Mercedes dismantlers in Glendale, Oregon at $100 for the entire bell housing assembly; I am not certain whether this includes the front planetary set but it would certainly cost a lot less to ship the parts rather than a whole transmission.
I will go out and pull that bell housing again and take pics of the damage I found inside.
If you drain the fluid and the pan is full of wear debris it will probably need more than what I have mentioned. But since these transmissions are no longer being made, consider the repair!

Once again, if this is the front planetary, it should be repairable; if so, ordering just the parts needed would be cheaper than shipping an entire transmission.

In my case I was fortunate to find an intact replacement, drove to their shop, threw the replacement in the trunk, went home and installed it.

And YES you should wear PPE when checking for pressure- face shield, gloves- crack the line just enough to see if it will spray. Dripping doesn't count.

Cheers,

snapped_bolt