300D wont shift beyond 2nd - PeachParts Mercedes-Benz Forum

tomo366 · #1 11-03-2009, 05:46 PM

My 84 MB 300D was shifting fine, drove 20 miles this morning came home and picked up my daughter and now it won't shift beyond 2nd gear and the shift into 2nd is real hard Reverse is fine...........I have owned the car for 7 years 3rd owner and never had a trans problem..........I assume it is a vacuum problem. Help!

TIA

compress ignite · #2 11-03-2009, 06:32 PM

Unplug the "KickDown Switch" and see if that helps.

mhin1956 · #3 11-04-2009, 09:01 AM

I had similar problem w/ mine not shifting. Re adjusted the bowden cable and that seemed to change things..not bad, not good. Bit the bullet and took it in to local shop to at least change fluid and filter (clogged was the suspsect). The called w/ good news bad news..good news is that the transmission fluid was clear. Bad news was that almost 1/2 of filter was sucked up into valve body. Good news is that after extensive cleaning, the car now has another 4000 miles on it an shifts like a dream..check your filter!

leathermang · #4 11-04-2009, 11:28 AM

Search for ' trans-x ' in the archives...
cheap, won't mess up any further or different problems, and has been known to cure problems with this same symptom completely... not hearsay.... I am talking about my cars...it is just a varnish solvent..

Biodiesel300TD · #5 11-04-2009, 11:45 AM

When there is a sudden change in shifting like that it has to be some broke or came loose. I would check the bowden cable. It is a cable that is attached to the linkages on the top of the valve cover near the firewall, and goes down to the passenger side of the transmission. It controls the RPM at which the trans will shift. Make sure it's attached on both ends. Then I would check to make sure you didn't loose your shift linkage bushings. When you loose these it can be tough to get the car in to gear properly, which could keep it from shifting properly. If these check out I would try adjusting the bowden cable to see if the issue changes. If it does then the cable it probably the isuse. If nothing changes, then I would start looking into trans fluid and filter.

fruitmeister420 · #6 11-04-2009, 01:36 PM

B2??

Bruce Bonds · #7 10-17-2010, 06:10 PM

Thanks Leathermang. My 84 300D would not shift into 4th gear but just flared. I changed the fluid and filter and included one quart of Trans-X. Still no 4th gear. I slowly drained a quart of fluid and replaced it with a second quart of Trans-X. I am happy to report that the transmission now shifts normally through all gears without flaring or harsh shifts. Thanks again for your suggestion. Now, should I continue to drive it with two quarts of Trans-X or should I change the fluid again?

tangofox007 · #8 10-17-2010, 07:11 PM

Quote:

Originally Posted by Bruce Bonds

Now, should I continue to drive it with two quarts of Trans-X or should I change the fluid again?

Trans-X is a strong solvent. Some things, like friction material adhesive, don't need to be so exposed. Especially not to two quarts.

turbo97se · #9 10-17-2010, 08:02 PM

check vacuum and other stuff like these guys mentioned. If not those, then rev the car up to close to redline. If it shifts and there were no other issues present then it sounds like a valve body. My '87 had this issue ... chased vacuum issues for some time!

RustyToy · #10 10-20-2010, 09:34 PM

my '84 300D did the same exact thing. It was 1 quart low on fluid. Start with the simple things first. Check your fluid.

Just my opinion.

Chris_87_300D · #11 02-17-2011, 03:17 AM

First - I'm out of town on vacation and not quite/yet stranded so any "quick check/fix" ideas are welcomed to get me home.

I'm having similar issues with my 87 300D as on this thread. It has about 345k miles on the orig transmission and engine. I've read many threads which indicate borrowed time after 200k miles on a transmission...

My issues:

About a month ago, on several rare occasions it wouldn't shift into 3rd or 4th. If I "bumped" the shifter (let off the gas, shift to N and back to D quickly) it'd kick in to the correct gear. Fluid was a little low, I expected that was the issue. Synthetic fluid is very clear and ruby red, probably a couple of years old and 20k miles or so.

Took a long (6hr) vacation trip - no issues except while coasting down a long steep 6% grade it neutraled while in gear. It got quiet and I looked down and saw my RPMs at 600 or so. Gave it another "bump" and back to normal. Took the car out to the store the night after the long drive (still hot) and no 4th at all. On the way home, no 3rd either. Next morning, no 3rd or 4th. The only semi-reliable option to have it looked at was a dealer (no other MBZ trans indies nearby) - on the way to the dealer (mid-morning), it ran fine through all gears about 80% of the way there and then no 4th and then, when almost there, no 3rd. Seems to shift better at shop temps (70 degrees) but not when cold or hot.

Dealer diagnosis: "Needs trans and torque converter. Performed trans working, governor and modulator pressure test, checked vacuum system, found valves in valve body sticking at times, when hot, unable to replace just valve body due to mileage, needs complete trans and torque converter, client declined" (my disclaimer - the repair est. was $6,500, before tax). Dealer also said, "If trans is replaced may not shift as designed due to leaking lines and transducers, please advice client may need additional work done with trans replacement. Checked engine and transmission mounts. Front and rear flex disks cracking." On a humorous note, they noted that "Oil was leaking. EVERYWHERE."

Questions:

1. Seems like a TransX is worth a whack since I'm pretty much SOL away from home. Is there any disagreement to dropping 2 qts and adding 2 qts of TransX and then driving it home (350 miles)? Or, is that too long to go w/ that stuff in there...

2. Would anyone recommend a 2nd set of eyes or is the diagnosis above reasonable (I'd expect that it is). The only question I have re: the diagnosis is if the valve body can be coaxed into a bit longer life by cleaning out the varnish or if it needs replacement asap.

3. Can the valve body be replaced w/o R&R the Trans? Is there any reason to just start with that or, due to the mileage significantly > 200,000k, is the only wise option to rebuild?

4. Is putting in a rebuilt torque converter a no-brainer if the tranny is out? How about a recommendation re: replacing (with factory rebuilt) or rebuilding the existing torque converter?

5. Can anyone recommend a good MBZ trans rebuilder in Northern CA (Sunnyvale, San Jose, etc.)? I presume that rebuilding my own (known quantity) transmission is wiser than purchasing a 3rd party rebuilt one that managed to "survive" Hurricane Katrina (and I can't afford an MBZ factory rebuild).

Thanks in advance.

Biodiesel300TD · #12 02-17-2011, 12:53 PM

Trans-X will not hurt anything. Some folks put it in when they refill the trans fluid as a preventative measure. You may see some difference you may not. I don't know the much about your specific model, but have you changed the fluid and filter recently. It might be due. Also make sure you have the proper amount of fluid. Low fluid can cause odd issues.

tobybul · #13 02-17-2011, 03:40 PM

Many W123 transmission issues such as shifting are normally caused by improper vacuum to the tranny. I've had flaring and shifting issues, tried trans-x, etc at first but no luck. Later traced it to low vacuum. Low vacuum are usually due to leaks. Many owners still leave the vacuum distributor sitting on the valve cover connected. I took mine out and plugged all the hoses per the advise of Mr Carlton and it cured my tranny issues.

Chris_87_300D · #14 02-18-2011, 12:48 AM

Thanks to you both - I put a quart of Trans-X in to give it a try, very unlikely to make anything worse and at least a small chance of improving things. It's not viscous enough for me to put in 2 qts, though - seems like that much dilution to the ATF would be somewhat risky.

I've got a full tank of gas and my plan is to get on the road, pray that I get it into 4th, and once I get it there I won't stop until I get there (or have to stop for gas)...

I'll check vacuum when I get back unless I'm forced to do earlier - I expect that the dealer would have eliminated this possibility but, as per above, his notes were a bit contradictory about this. He was all up in arms because I removed the post-delivery pressure/vacuum changes to reduce cruise control surging because the tiny orifices kept plugging up and disabling the turbo. I have a fix that seems to work fine without all of the trouble and plumbing.

I guess that I'm really lucky to get 345k out of my tranny - I didn't realize that would be exceptional. Hopefully it won't be a 10 hour drive home instead of 6...

Chris_87_300D · #15 02-18-2011, 12:57 AM

Quote:

Originally Posted by tobybul

Many W123 transmission issues such as shifting are normally caused by improper vacuum to the tranny. I've had flaring and shifting issues, tried trans-x, etc at first but no luck. Later traced it to low vacuum. Low vacuum are usually due to leaks. Many owners still leave the vacuum distributor sitting on the valve cover connected. I took mine out and plugged all the hoses per the advise of Mr Carlton and it cured my tranny issues.

I haven't found Brian's post yet on the 4 way distributor...still looking though. This would be a quick possible fix of a bunch of potential leaks.

From the following 603 vacuum diagram: http://i323.photobucket.com/albums/nn447/Jeremy5848/1987%20Mercedes%20300D/Vacuum603.jpg,

Is the only necessary line the one that goes to 65-VACUUM DISTRIBUTOR? It looks like the two on the left could be disconnected (I've effectively done that already, but at the other ends so some leaks may exist). I'm not sure what "c - other ancillaries" would be for unless it's the HVAC control stuff (which I need). The stop unit #6 via the key shut off look to be driven off the large servo vac hose.

By the way, what are the ATM (line a) lines coming off the EGR and recirculating air valve vacuum transducers? Do these just open to the passenger compartment or do they drive all the HVAC vacuum switches?