Is my transmission failing? - PeachParts Mercedes-Benz Forum

firstdiesel · #1 04-17-2013, 03:49 PM

I read through as many links as I could find that was similar to mine, but nothing exactly.

I was offroading about a month ago, well not really off roading, but I was parking in a grass lot for an event and all of a sudden the transmission started to slip? Engine revved and no power to the transmission twice, maybe three times while driving on an uneven grass surface. Went to the event, came back and no problems, shifting fine. Shifting seems okay since then aside from a quick 2-3 shift which I've had for a while.

Two days ago I'm coming out of a regular parking lot this time, normal operating conditions, and I brake at the intersection. I look for traffic, go to accelerate and no acceleration. If felt as if it wanted to grab, short bumps like it wanted to, but didn't. I let it go back to idle and then eased into it and it drove, almost normally. Brake at the traffic light and before I could come to a complete stop I went to continue and it flared as I released it engaged and then drove normal again.

Since then, normal shifting with an occasional bump when transferring from braking to driving without a complete stop.

Fluid level is normal, fluid and filter changed less than 1500 miles ago (2-3 months). Trans mount replaced.

Only problem is that I am chasing a door lock vac leak on the "unlock" side of the system. Will fix that this weekend.

Does that sound vac related, B2, K1, converter, rebuild or something very simplistic that can be fixed cheaply and quickly?(yeah, right!) I would like to fix this before I'm stranded.

Thanks

Todd

junqueyardjim · #2 04-17-2013, 08:20 PM

Well, easy things first, it is not vacuum - never. Vacuum is only there so you don't feel the shifts so much. So, go on to the main things. Looks like your car has 275,000 plus miles. They will all fail at some point. 275,000is a lot of miles, and perhaps it is pretty much untouched. You state that you have changed oil and filter. Did you change the convertor also? It is kind of a pain, but not difficult really. Just a bit messy. If you did not change the convertor oil, I would dump it again, drain the convertor, and a new filter. I think it is highly likely that you have some debris in the valve body and it moves around, so then it works, then it doesn't. As a part of the refill, I think I would ad some specific transmission additive, like STP or NAPA or LUCAS - yea Lucas, help us pay for the football field. But it might help. Then carefully fill it exactly to the level. Put in your additive, add 5 quarts - start it and slowly run it through the gears, leave it run and check it and bring it up to the add oil mark. Then take it for a 2 or 3 mile drive, park it in same place, then with engine running check oil and add as necessary - very carefully.

firstdiesel · #3 04-17-2013, 08:59 PM

Thanks Junqueyardjim. No I didn't drain the torque converter with the change, I don't know why I chose that route, but I guess I should have.

When I did change the fluid, I followed posts from here about do's and don'ts, and when I got a look inside the fluid was just slightly brown but mostly the correct color and did not smell foul or burnt. There was no debris in the pan or filter, that I could see, but there was some white-ish foam where there were cracks in the pan gasket/sealant, which means it must have been a while since the last change.

The forum has mixed feelings about additives, but I see your point. If I can get 1-2 years more I hope I'm in a place to get a good rebuild. Is there a "flush" of some sort, or should I stay away from that with the trans having so many miles?

Stretch · #4 04-18-2013, 12:57 AM

If you didn't drain the torque converter then I'd guess that your fluid is going to be murky again by now. It is a bit of a gamble (cost wise if the transmission needs lots of work) but it is probably worthwhile changing it again - this time drain the torque converter though. Put in a new filter too.

A flush is a waste of time in my opinion.

The white foam isn't a good sign - that could be emulsion => water ingress. Have you been loosing coolant recently?

Have you checked the shifter bushings?

Get your vacuum leak fixed as well - it does have an effect on the modulating pressure though not to the extent of the earlier vacuum only transmissions.

firstdiesel · #5 04-18-2013, 10:12 AM

Thanks Stretch, I have been losing coolant, but I know from where. It seems that is is leaking right near, or at, the plastic radiator drain plug, which I also need to replace as I can see drops on the garage floor right under it and on the lower front faring.

In a previous thread I posted a picture of the foaming here:

Trans VCV and modulator question.

Post #4. It is exactly where the gasket was cracked so I attributed it to air versus liquid, course if its raining it would be air and liquid.

The shifter feels solid with little or no slop in the linkage, but I have had some problems pop up before the shifting issue where I am unable to start the car in park. I put it in neutral and it starts right up and then I am able to start the car in park for days at a time, no problem. If it sits for more than a day or so I have the no start in park problem.

I'll climb under the car and look at the shifter bushing. Last time I was under there it was whole and yellowed, but whole.

The vacuum with be dealt with this Saturday.

zakatekaluka · #6 04-18-2013, 11:04 AM

I am just going to add my two cents and second the suggestion to check the shifter bushings. Your problem sounds exactly like the one we struggled with for months in our 85 300TD. The last straw was when I tried to start it and couldn't, but then got it going in neutral just like you said. It almost took a very pricey trip to the transmission shop when someone asked if we had checked the bushings. DUH moment that saved us so much time. Hope it's a cheap fix for you, too!

Stretch · #7 04-18-2013, 02:40 PM

That foam is a bit strange.

Here's the picture from your other thread (I'm glad I hadn't contributed to that thread - that would have been embarrassing!)

I'm a bit concerned that your radiator MIGHT be leaking between the water and oil cooler side. If you find white foamy muck in there the next time you change the oil and filter then I'd be tempted to swap it out / get someone to test it just in case (as well as the cooler lines). However, if you can fix the leak that you know you've got and it stays good then you'll probably be OK.

Let us know how you get on with the shifter bushings.

firstdiesel · #8 04-18-2013, 06:17 PM

zakatekaluka, I hope it is too!

Okay here's a little update on the drivablilty of the car. I had to go about 15-20 min of highway driving south of me this afternoon. Car performed as it normally should, stopped at the first traffic light after my drive and slip, slip, slip, barely engaging the transmission. Nursed it to my location expecting it to be towed. 30 min later went out started it and it drove away normal again. Took a 1-1000 count to go into reverse, so about 2 whole seconds. Drove a little soft and by the time I got home, it was somewhat normal again!

Could someone enlighten me on the symptoms of a failing torque converter for my own knowledge, not saying that is what it is. I think I'll be looking into the bushing tomorrow morning instead!

Stretch, thanks for the photo. Now people can see it better. I'll get a shot of the bushing as well.

firstdiesel · #9 04-23-2013, 04:39 PM

Update:

I climbed under the car and snapped a couple of photos of the bushings. The front bushing actually looked relatively new like the new nylon clear type bushing. It is still flexible and not yellowed. The rear bushing looks like it was replaced, but did not look like the front one. It had a Mercedes part number on it so I am assuming that it is correct. I did change that one out with a new clear nylon one since it was easy to access and I was already down there.

The car seems to shift nicely and starts in park so far but if I am in first and coast a little and then accelerate again I can sometimes, sometimes, feel a short slip. Problem now is that I hear a tinny, not tiny, high pitched noise at around 2000 rpms that seems to change with the rpms and not speed.

I just got a quote for a rebuild on this transmission for $3000!

Don't know what I'm gonna do, but it isn't that yet. I got an online quote for $1600 rebuilt transmission and torque converter with 2yr warranty $100 shipping both ways and $800 core charge from these people: Rebuilt Automatic Transmissions & Gears - Rebuilt vs Remanufactured - Auto Car & Truck Transmissions anybody ever use them?

It seems to slip more after highway driving, could this be a heat thing? There is no oil or transmission fluid in the expansion tank, it is clean and clear.

Stretch · #10 04-24-2013, 03:31 AM

Well if you can't feel any movement in the bushings then I guess they're OK.

You could very well be just at the end of the life of the transmission friction parts. However, before we go all doom and gloom on the beast how about having a read of this?

'84 300SD Transmission Issue (1=>2)

Does anything there sound familiar?

Could it be B2?

Put it this way checking / sorting out a B2 piston is less expensive than a rebuild but it might not fix it...

firstdiesel · #11 04-24-2013, 08:44 AM

Thanks Stretch, I read through the post and I don't know if it will fix it, but as I have been driving very short distances lately it seems to be ok but over longer distances is when I am seeing the 1st gear start to slip. I am willing to roll the dice on a K1, B2 just to find out and save the big cash even if it ups the tally in the end.

What would cause a whine, that I am not sure is coming from the transmission, that is relative to rpms in the transmission? Does that make sense? Would it be a pump or T/C?

How hard is it to remove the transmission without a lift? I'm really considering taking motor and trans out and hitting all the engine leaks while out of the car. Just don't know if I can afford the down time, its my everyday driver and I don't have the stable some other members have.

chasinthesun · #12 04-24-2013, 11:10 AM

If you see that those bushing linkage pieces are good their is another suspect in this area ,its the bolted rod that extends down to the linkage ,its in one of your posted photos.UNbolt this end and inspect it for wear its afitted bolt into a sleeve ,youll see what I mean you you unbolt it ,resecure and make sure its tight.I just had an issue were I had thought my trans was a goner, I had some slop in the shifter but wasnt looking at that at the time ,A Couple of weeks ago I went to put it in gear and whala ,its good, changed those linkage bushings and found that bolt was not tight and had oil all over the place.Been drivng since then with no issues.Its probably a fine detail were that shifter ends up to let the trans perform its operation.

firstdiesel · #13 05-06-2013, 08:49 PM

Well I've only drive the car about a mile or so daily so I have been driving it real easy and all has been "okay".

Here is a question: Is a torque converter for a 722.315 that hard to find?

I've been doing research to see if it could be one of my problems. Here is what I found out about bad torque converter symptoms:

Loss of power
Transmission slippage
Torque converter noise (grinding or whistling noises)(I have a whistling/whining noise)
Abnormal transmission engagement (mine hesitates slightly before driving forward)
Transmission surging

With that in mind I called a couple of T/C shops locally and asked about mine and they all say they don't have one! I give them the part # from my local Mercedes dealer and they have no matches. One person said there is a code stamped into the T/C and I will have to pull it to find out what it is.

Here is my plan:

Remove transmission
Replace T/C
Replace pump and shaft seals
Replace rear shaft seal (its out, why not)
Replace ,as point of maintenance, the B2 valve and seals/o-rings
Replace ,as point of maintenance, the K1 spring
Replace filter and gasket

I'm talking a couple hundred vs. $1600-$2000+ here.

Any ideas?

Oh, and I was having shifting problems earlier in the year and took care of that through fixing vac leaks and adjustments from advice on the forum. A month or so after that, I have the aforementioned post.

biopete · #14 05-07-2013, 01:35 AM

I'd start with a valve body. You'll probably need that anyway. They are easy and can be cheap. I got one for 100.00 and another for 150.00. I wish I would have gotten a valve body when my trans first started acting up. Instead I spent a lot of money on flushing and additives. Then reverse went out and needed a new trans. Then after that I still needed a valve body. I think driving with the bad valve body accelerated the demise of my trans. And I think new fluid releases gunk in the valve body causing it to need real cleaning. Just thoughts though. I don't know anything about transmissions.

Stretch · #15 05-07-2013, 02:53 AM

Quote:

Originally Posted by firstdiesel

Well I've only drive the car about a mile or so daily so I have been driving it real easy and all has been "okay".

Here is a question: Is a torque converter for a 722.315 that hard to find?

I've been doing research to see if it could be one of my problems. Here is what I found out about bad torque converter symptoms:

Loss of power
Transmission slippage
Torque converter noise (grinding or whistling noises)(I have a whistling/whining noise)
Abnormal transmission engagement (mine hesitates slightly before driving forward)
Transmission surging

With that in mind I called a couple of T/C shops locally and asked about mine and they all say they don't have one! I give them the part # from my local Mercedes dealer and they have no matches. One person said there is a code stamped into the T/C and I will have to pull it to find out what it is.

Here is my plan:

Remove transmission
Replace T/C
Replace pump and shaft seals
Replace rear shaft seal (its out, why not)
Replace ,as point of maintenance, the B2 valve and seals/o-rings
Replace ,as point of maintenance, the K1 spring
Replace filter and gasket

I'm talking a couple hundred vs. $1600-$2000+ here.

Any ideas?

Oh, and I was having shifting problems earlier in the year and took care of that through fixing vac leaks and adjustments from advice on the forum. A month or so after that, I have the aforementioned post.

If you are prepared to go through all this trouble I reckon you'd be better off buying some gauges and making some measurements first.

(I don't know why but I got the impression you weren't really up for some in-depth work)

What you are essentially saying is that you want a rebuilt transmission without the bands and the clutch plates - to my mind that seems a bit strange if you are going to go through the trouble of the other stuff...

...the problem is that if you are not careful the fixing of a little problem gets turned into a full on rebuild - is that really what you want?