2010 Mercedes B180 6 speed manual gearbox problem.

[DonaldDukw]

Hi
My wife's 2010 Mercedes B180 6 speed manual has developed a gearbox problem.
Stationary I can select all gears perfectly. With the engine running and driving I can change up OK ( it feels a little stiff) but changing down is an issue. For example, I can't change down from 5th to 4th ( or lower) until engine speed drops low enough - then it drops in with a small clunk. There was no grating noise when I tried... it just won't enter the gear like it is blocked or the gate does not exist. This is the same going down through all gears. I

The clutch seems fine. Car has about 130k miles on it.

I hope it's not the synchro but expect it is

If it is the syncnro - is it an engine out job?

Any advice welcome.

Thanks

Don

 

[mattkh]

I do not have 2010 B180 manual.
Q1. Did it develop this over a few days or suddenly..?
Q2. Stationary but engine running, can you select all the gears..?
Q3. Have you done a uphill check to test for a slipping clutch..?
Q4. Can you see any signs of an oil leak..?
Finally a request for a picture of the engine bay showing the gear linkages please. This should also confirm whether the engine is lying transverse or otherwise.

 

[DonaldDukw]

Hi
Thanks for the reply
Q1 = slowly getting worse she says. Stared with first/2nd.
Q2 = Yes
Q3 = Yes - clutch is fine - there is no grating noise changing gears - just doesn't want to engage and I didn't want to force it.
Q4 = no leaks.
Dark here now. Will try tomorrow
Thanks

 

[mattkh]

Dark here now. Will try tomorrow
Thanks

Thanks.
Is the 1st to 2nd now better..?

 

[LostKiwi]

You're describing the symptoms of clutch drag where the clutch doesn't fully disengage. You therefore end up forcing the gear selection through the synchromesh which is why it's stiff and clunky. You can easily prove this if you know how to double declutch (not holding my breath on this as it's not something taught for the past 40 years or more).
The technique is as follows:
When coming down the box (5th to 4th for example) push in the clutch, move to neutral, release the clutch, blip the throttle to match the revs, engage the clutch (before the revs drop) move to the gear you want, release the clutch.

You need to be able to do this quickly for it to work.

This NOT a synchro issue, it's most likely clutch adjustment, clutch wear or if the clutch is hydraulic low fluid level or leak.