Transmission Slipping, do I have to replace it?

This is my first post so please let me know if I need to post more info!

I have a 2002 T1N Freightliner 2500 with 135,000 miles on it. Over the last few weeks I have started noticing some transmission slipping, or flare shifting (I guess it is called). It starts to really act up once the engine is warm and seems to have gotten worse over the last couple days. It used to just happen between 3rd and 4th gear but now it seems to be more frequent.

History:
I had the ATF fluid changed 1,000 miles ago in Montana. I found out later the mechanic did not drain the torque converter, used about 6 qts of BG Universal ATF, and noticed a fair amount of metal on the drain magnet.

Forward to last week. The CEL comes on and throws a P0100-128 Mass air flow sensor: Plausibility. Simultaneously, we notice a very slow leak (only leaks when running) in the transmission, which appears to be coming from the wiring harness.

I replaced the MAF, had the codes cleared, the transmission adaptations reset, and the ATF fluid checked. The transmission was found to be slightly over full, but the tech said he didn’t want to correct the fluid level because of the leak.

The CEL light has not come back on, but the tranny is still flare shifting, possibly worse now. I took the van into Superior Auto in Medford (the MB dealership was backed up for months), and they declared very confidently that it would need to be replaced.

Is there anything else I can do!?! I’m at the end of my rope talking to dealerships and reading forums. I live a long way from sprinter service centers (Mt. Shasta, CA), but the head mechanic at Superior claims he worked on the sprinter side of a MB dealership for a good number of years and is familiar with the transmission. Would appreciate any advice! Thanks!

From what you wrote it seems like you never drained the wrong fluid and did a torque converter drain as well. These need the correct fluid found here. https://www.idparts.com/transmission-service-kit-fluid-nag1-p-3048.html For another $10 id parts has the replacement socket to stop your leak. To me a full drain and refill with proper fluid and cleaning the harness connector would be an economical test before deciding something else is going on like an internal clutch etc.

veganxxx said:

From what you wrote it seems like you never drained the wrong fluid and did a torque converter drain as well. These need the correct fluid found here. https://www.idparts.com/transmission-service-kit-fluid-nag1-p-3048.html For another $10 id parts has the replacement socket to stop your leak. To me a full drain and refill with proper fluid and cleaning the harness connector would be an economical test before deciding something else is going on like an internal clutch etc.

Click to expand...

So is the BG ATF fluid not the correct fluid to use? I've talked to several people and there seems to be some disagreement as to whether that is part of the problem. Also, the general consensus seems to be that draining the torque converter isn't a likely explanation for the slipping in the transmission. Just curious and trying to make sense of all the info, Thanks!!!

If your fluid level is too high, it can cause the fluid to foam. That can lead to catastrophic failure in your Nag1 transmission. I would also do a complete Trans service(correct fluid/filter/connector) Drain the TC. Check for wicking up to TCM. Double check your ATF is at the correct level at prescribed temperature.

pyles said:

... and noticed a fair amount of metal on the drain magnet.
...

Click to expand...

Metal muck/dust or chunks? Muck is not unusual.

Assuming muck.

pyles said:

So is the BG ATF fluid not the correct fluid to use?...

Click to expand...

My opinion. New BG ATFIII type fluid would probably not be a problem yet. Not staying with MB spec fluid would become more a problem as the miles pile on. It is arguable that there are good ATF fluids which are not on the MB list.

That said, not draining the TC (and not changing the electrical connector body) during the maintenance service may have you in the situation you describe. I would change the TC/pan fluid and connector body as suggested and see if the problems go away. After the complete change maybe change to a bit harder driving/acceleration mode for a time to see if the flare shift changes. Sometimes all the time gentle driving isn't always the best.

If that doesn't work the next step for me would be to clean the valve body as outlined by Doktor A. The new fluid can be properly drained and re-used if the valve body needs cleaning.

vic

Aqua Puttana said:

Metal muck/dust or chunks? Muck is not unusual.

....Assuming muck.

vic

Click to expand...

Yeah he said there weren't any chunks, just much and smaller debris. Okay so it sounds like starting from the ground up might be a good approach. I'm gonna call and talk to the mechanic and see what he can do.

I would first replace and stop the electrical connector leak before it wicks up into the transmission control unit under the drivers seat! Then make sure the transmission fluid is not overfilled! If problems do persist then go back and drain the transmission and TC and - while you are in there, clean the valve body as Vic suggests per the Dr. A procedure and then replace the ATF with Sprinter approved fluid (don't overfill!) Only then would I consider that your transmission may actually need replacement but I would still see if other remedies/procedures are recommended here on-line before proceeding! Silver Star transmissions has been highly recommended for obtaining a quality rebuilt transmission but eliminate all other possibilities before taking this action! Too many shops and mechanics just don't know Sprinters and tend to use the "Hammer" approach to Sprinter problems - even some of the Mercedes/Dodge Dealers who don't happen to have a good Sprinter T1N mechanic on staff! Good Luck and keep on posting your progress!

Thanks for the input everyone. I brought up these concerns to the Medford mechanic and he wouldn't hear it so I'm done with that guy. Unfortunately, my girlfriend and I are on the road so I don't have access to the tools to do most of this work. After a whole day of calling around I got referred to Capitol City European Automotive in Sacramento. Michael, the head mechanic, said they would typically correct the fluid level, check the valve body, and TC before doing anything else. Gonna give these guys a shot.

I am nearly positive if you drain, refill, replace the connector because it is leaking and confusing your transmission computer TCU all will be well. It needs to be clean and dry because electrical sensors communicate through the 10$ plug. ANY mechanic should be able to do a drain and refill properly, although you need the Mercedes dipstick and the correct fluid. I use Shell 134 it is cheap and OG fill according to Dr. A!! available by the case anywhere that sells Shell oils like an industrial lubricants place, shell lists them on its own website.

Also, the trans needs the exact right amount of the correct fluid. this is maybe one hour of work, if you were at my house you'd be gone before lunch!!!!

Quick Update: I called and talked to the Folks at Cap City European and they quoted me a ridiculously high number for the a potential tranny replacement. Consequently, I am thinking about going with another shop. Three Points Star Motors has really good reviews and advertises that they work on sprinters. I talked with the owner and he said that they would run a diagnostic but he felt the symptoms pointed to a mechanical issue and that the tranny would likely have to be replaced. He basically said that if they found any pieces of steel or clutch plate when they drained the fluid, that would be confirmation that the tranny was shot. Should I be worried about that mentality in a mechanic? Is it better to find a mechanic who is committed to to finding a fix without replacement? Or is any mechanic worth his salt going to check the obvious before pushing a new transmission.

The big reason I ask is because the shop at capitol city seems to think they can fix the problem without replacement, but quoted me $2,000 more if it comes down to needing a new transmission. I don't want to take it to them, and then have to move it to another shop if it turns out they can't fix it.

Thanks for all your help eveyone, can't tell you how much I appreciate it.

Has service provider listened to the suggestion of a complete drain and fluid replacement?

pyles said:

... He basically said that if they found any pieces of steel or clutch plate when they drained the fluid, that would be confirmation that the tranny was shot. Should I be worried about that mentality in a mechanic? ...

Click to expand...

I thought that you already said there were no chunks when the pan/filter was done? It does sound a bit like he's preparing you for the transmission which he plans to install.

Let us review.

pyles said:

... Over the last few weeks I have started noticing some transmission slipping, or flare shifting (I guess it is called). It starts to really act up once the engine is warm and seems to have gotten worse over the last couple days. It used to just happen between 3rd and 4th gear but now it seems to be more frequent.

Click to expand...

1000 miles ago a partial service was performed. BG fluid was mentioned.

pyles said:

...History:
I had the ATF fluid changed 1,000 miles ago in Montana. I found out later the mechanic did not drain the torque converter,
...

Click to expand...

1000 miles ago and now a bit worse.

pyles said:

...Forward to last week. The CEL comes on and throws a P0100-128 Mass air flow sensor: Plausibility. Simultaneously, we notice a very slow leak (only leaks when running) in the transmission, which appears to be coming from the wiring harness.
...

Click to expand...

Could be related to oil wicking/harness, but if it is that is the first time that I've heard it here.

pyles said:

...I replaced the MAF, had the codes cleared, the transmission adaptations reset, and the ATF fluid checked. The transmission was found to be slightly over full, but the tech said he didn’t want to correct the fluid level because of the leak.
...

Click to expand...

Over full.

pyles said:

...The CEL light has not come back on, but the tranny is still flare shifting, possibly worse now. I took the van into Superior Auto in Medford (the MB dealership was backed up for months), and they declared very confidently that it would need to be replaced.

Click to expand...

Is that the same people that didn't bother to drain the TC and change the electrical connector body during the transmission service?

pyles said:

...Is there anything else I can do!?! ...

Click to expand...

Yes.

Goofy foot mentioned foaming. Foaming would be more prevalent after warm up and fluid circulation. You know the transmission is somewhat overfull.

I mentioned that you really should have a TC drain among a couple other things.

It would be best to have MB spec fluid.

Flare shifting is not unheard of with Sprinters. My 2004 with 320,000 miles occasionally flares. I am normally easy on the go pedal. After any flare incident I drive a bit harder for a while. The flare has always gone away. Been doing that for over 100,000 miles.

If the transmission is truly slipping then it could let you down. I can say that a flare shift of itself is not necessarily fatal. If it is accurate that no chunks were found, that is a good sign. Muck is from normal wear and tear.

I suggest that you go back and review the replies.

Good luck.

vic

So does anyone know if the original poster tried the helpful suggestions? My son’s 2003 with a rebuilt transmission has been slipping and I’m making him aware of this post. Thanks for all of the input.

Lack of followup can be frustrating...
Pulling the 13-pin connector from the transmission will show any leakage (it should be dry inside) and a hot-check of fluid level will diagnose an over-fill. In extreme cases the foamed fluid will bubble out the vent on top of the case and soak everything.
A sump and TC drain and fill uses about 7 quarts. Pan-only drains about 4, so the OP’s statement that the service tech poured 6 quarts put him firmly into “too full” territory. The level is checked hot, idling in park, and corrected for sump temperature.
As stated, because air is a lousy lubricant, foaming fluid can seriously damage the friction plates and bearings. It also drops the fluid pressure, which exacerbates the problem.

-dave

pyles said:

Quick Update: I called and talked to the Folks at Cap City European and they quoted me a ridiculously high number for the a potential tranny replacement. Consequently, I am thinking about going with another shop. Three Points Star Motors has really good reviews and advertises that they work on sprinters. I talked with the owner and he said that they would run a diagnostic but he felt the symptoms pointed to a mechanical issue and that the tranny would likely have to be replaced. He basically said that if they found any pieces of steel or clutch plate when they drained the fluid, that would be confirmation that the tranny was shot. Should I be worried about that mentality in a mechanic? Is it better to find a mechanic who is committed to to finding a fix without replacement? Or is any mechanic worth his salt going to check the obvious before pushing a new transmission.

Click to expand...

Within the industry, that is known as "panning for gold". If there is brass, bearings, or chunks of friction material in the pan, it's done.

The big reason I ask is because the shop at capitol city seems to think they can fix the problem without replacement, but quoted me $2,000 more if it comes down to needing a new transmission. I don't want to take it to them, and then have to move it to another shop if it turns out they can't fix it.

Thanks for all your help eveyone, can't tell you how much I appreciate it.

Click to expand...

There is nothing in life that cannot be done a little worse for a little less money.

And unfortunately, that can lead to multiple repair attempts that vastly exceed the expense of a competent repair. Sometimes it involves multiple repair attempts (at your expense) done by someone who isn't up to the task, PLUS the additional expense of a subsequent competent repair done by someone who is up to the task. And at that point, the competent repair usually costs more than it would have cost to begin with.

Real easy to financially jump from the frying pan into a Chernobyl Reactor #4 on this one.

Local trans places will sometimes offer deals on rebuilding the NAG1. Its not a difficult unit overall. These rebuilds are generally just replacing wear parts, and seals, and anything broken. They don't overhaul the valve body unless its needed, and they may not have a test stand. It can be worth it if you are tight on funds. Really, a full reman (silverstar etc) is the best route. You will essentially get a new transmission, that should provide OEM levels of life.