1987 300TDT Wagon transmission slipping and no power at slow speed when cold. - PeachParts Mercedes-Benz Forum

ah-kay · #1 10-11-2019, 07:10 PM

Is there any correlation between slipping transmission and lack of power at slow speed? When I leave my house everyday the car has to climb a small stretch then the road levels out. It is not steep at all but it always struggles to do the 200' or so. I floor the pedal but it moves gingerly. It is much better when the car is at temperature doing the same stretch. The car has good power on the freeway, doing 80+ mph with ease. Is there anything I can check or measure to see why? The transmission is definitely slipping as it hesitates to shift or shift at high rev. Any ideas are welcome.

SkippyJasper · #2 10-11-2019, 07:16 PM

Low transmission fluid comes to mind. It expands when warm and probably just meets the minimum level.

How long since the last transmission drain, filter and refill?

That vintage had a no maintenance (sealed for life) recommendation from MB. That has since been changed to a service every 40-60,000 miles.

Sent from my iPad using Tapatalk

ah-kay · #3 10-11-2019, 07:46 PM

Quote:

Originally Posted by SkippyJasper

Low transmission fluid comes to mind. It expands when warm and probably just meets the minimum level.

How long since the last transmission drain, filter and refill?

That vintage had a no maintenance (sealed for life) recommendation from MB. That has since been changed to a service every 40-60,000 miles.

Sent from my iPad using Tapatalk

Transmission fluid level had been checked and is at level.

Father Of Giants · #4 10-12-2019, 10:12 AM

Quote:

Originally Posted by SkippyJasper

Low transmission fluid comes to mind. It expands when warm and probably just meets the minimum level.

How long since the last transmission drain, filter and refill?

That vintage had a no maintenance (sealed for life) recommendation from MB. That has since been changed to a service every 40-60,000 miles.

Sent from my iPad using Tapatalk

The sealed for life transmissions came out in 1998

Diesel911 · #5 10-14-2019, 12:02 AM

When I had that slipping when it was cold on the 84 300D changing the Filter and fluid cured it for about 1 year then my B2 piston broke.

Also even if you have the updated B2 piston and the updated nylon bushing for the B2 piston to slide on there is still a Lip Seal that has been there since 1987.

In the pic the B2 piston is removed and you see the seal and behind the seal is an amber colored ring that is the old type aluminum bushing that is replaced by a nylon one.

Usaguy · #6 10-14-2019, 01:48 AM

Quote:

Originally Posted by ah-kay

The transmission is definitely slipping

Hook up a T fitting on the line going to the vacuum modulator so that you can run a vacuum gauge into the car and observe what it's doing while you push the pedal. Also check that vacuum connection and report back.

Quote:

Originally Posted by ah-kay

Is there any correlation between slipping transmission and lack of power at slow speed?

bowden cable - regulates transmission shift point
vacuum modulator - regulates shift quality

I don't see how any of these two can have an effect on engine output since it's a mechanically controlled tranny (unless bowden cable is stuck and holding the linkage but you would feel that in the pedal)

Another possibility is that something binds up or a clutch pack engages in the transmission causing drag when it's cold (there is a check for that)

Diseasel300 · #7 10-14-2019, 10:17 AM

Quote:

Originally Posted by ah-kay

When I leave my house everyday the car has to climb a small stretch then the road levels out. It is not steep at all but it always struggles to do the 200' or so. I floor the pedal but it moves gingerly. It is much better when the car is at temperature doing the same stretch.

Is the RPM high and the car fails to pick up speed during this event? If not, the trans is NOT slipping. It's in the wrong gear, you have fueling issues, or your turbo is a POS and doesn't spool until it the oil gets hot.

Delayed shifts, or shifting at stupid high RPM is due to the bowden cable being too tight. WOT shifts leaning on the downshift button should be ~4600 RPM. Normal WOT upshifts should be somewhere around 4100 RPM. I went through similar issues with my SDL.

dlssmith · #8 10-14-2019, 04:39 PM

I concur on the turbo issue. And in particular the cat converter. I have had experience with them clogging more cold than hot when they are getting older. I would check all vacuum lines as well. Sometimes they act differently cold to hot.

ah-kay · #9 10-31-2019, 12:47 AM

I suspect the turbo is no good or not spooling. I have a good turbo from another car that just quit. I want to swap it in to check out. But before I do that, is there any quick way to confirm the turbo is the culprit? It is ok if there is none, no harm asking.

Diseasel300 · #10 10-31-2019, 10:49 AM

So.........trying to fix a slipping transmission by replacing the turbo? Blinkler fluid? Snake oil?

Seriously...you never followed up with ANY of the questions asked in this thread by anybody. Did you diagnose the trans as slipping? Just low power? Miss Cleo doesn't read these boards.

ah-kay · #11 10-31-2019, 11:41 AM

Quote:

Originally Posted by Diseasel300

So.........trying to fix a slipping transmission by replacing the turbo? Blinkler fluid? Snake oil?

Seriously...you never followed up with ANY of the questions asked in this thread by anybody. Did you diagnose the trans as slipping? Just low power? Miss Cleo doesn't read these boards.

I have spare turbo, the car has no power so I decide to change the turbo first. Slipping transmission could be in my mind. One thing at a time.

Diseasel300 · #12 10-31-2019, 11:51 AM

Quote:

Originally Posted by ah-kay

I have spare turbo, the car has no power so I decide to change the turbo first. Slipping transmission could be in my mind. One thing at a time.

Ok. If you resolve the power issue, the slipping should be much more noticeable too. I will attest to a crappy turbo failing to spool when cold. Before I rebuilt the turbo on my SDL it was a serious dog off the line when cold. Almost dangerously slow. Once the oil got hot, it seemed fine. After rebuilding the turbo it was like a completely different car.

86-300sdl · #13 11-02-2019, 12:25 PM

Hey bud....did you try bypassing the over boost vac line to alda?