PFDGSB

Going to look at an 87 S4 Auto, 110,000 miles.
I'm told the car shows, runs and drives well, but the auto tranny shifts "clunky" at low speeds, better at higher speeds.

The gent said "all of these Mercedes trannys shift like that." I'm sure that's not the case. But, should I be worried about a clunky-shifting transmission? Is this a fluid issue, or a tranny that's on its way out?

I haven't driven it yet. Clunky is how it was described to me.

Thoughts?

gazfish

If clunky= hard shift between every gear then could just be a vacuum leak in the pipe from the Engine. Has the current owner checked the fluid level or done any investigation other than saying it’s normal?

PFDGSB

The car is in Northern Vermont. It is owned by a dealership that typically sells higher-end cars. Keep in mind, that a higher-end car in northern VT might be different than a higher-end car in Beverly Hills.

I'm not aware of any work that has been done to try to fix the clunky transmission.

However, the car is coming with many good service records. Aside from the clunky transmission issue, all appears to be very well with the car, including a timing belt 10,000 miles ago.


If you think it could be a vacuum line, or fluid issue, that's great.

Any other known issues with these transmissions that might make it shift hard?

Tranny mount?

FredR

Clunky low load/low rev shifts is the classic sign that vacuum is not getting through to the shift modulator on automatic transmission units [driver's side as I recall] - that or the modulator itself is caput [very rare].

Usually an easy DIY fix. There is a multi way vacuum connector at the back of the inlet manifold and one of the lines services this functionality- it disappears over the bell housing via a nylon tube, transitions to a hard pipe along the torque tube and then back to nylon or tubing as it enters the modulator. The modulator itself also has a rubber cap and that needs to be functional or the same problem can happen [as I found out not long ago].

The system is easy to test and relatively easy to fix if problematic as sounds likely to be the case,

PFDGSB

Sounds good. I won't let the clunky tranny be a deciding factor.

FredR

I would ask the seller to attend to this relatively simple issue to prove the point at hand. They need to prove that the line from the engine bay to the tranny is not blocked and then demonstrate that when vacuum is applied at the engine end of the line and connected to the modulator it holds vacuum. The line could be blocked and something could also have failed to cause a leak. If there was nothing wrong to start with or proving the system does not solve the characteristic, then something else within the tranny is causing the problem and that would be much more worrisome.

Whereas the chances are the problem most likely lies in the vacuum not getting through to the modulator, one should not take that for granted without proving the point.

SwayBar

I do not agree at all.

If they're giving the car away, yes.

PFDGSB

I didn't end up going to see it. Will call them today and ask if they want to address they tranny.

Thanks for all of the quick feedback.

Mrmerlin

you should also get the flex plate checked before you buy the car,
this could be a buzz kill if the thrust bearings worn out