520D auto / ZF 6HP possible problem..

Evening.

In another thread I talk about a problem with my harmonic balanced failing. Now the rough idle when stationary in D is getting worse. I’m suspecting I may have a gearbox fault.

It seems to only happen when the car is warmed up, my initial thinking was as the harmonic balanced rubber warms it loses stiffness and vibrates with the engine under load. Prior to this I thought it was an injector issue causing a rough idle.

This evening I’ve noticed another issue which was a lightbulb moment

While creeping slowly in D or R, ie: parking, I felt the car surging ... as if I was lightly tapping the brakes every second.
This then rang a bell with me, i previously had experiences on the motorway when cruising that occasionally I would feel a very very slight and sudden deceleration as if once again I had lightly tipped the brakes.

Has anyone experienced issues like this before??

I’m very concerned that it is the torque converter on the way out but hope fully something simpler like the valve body seals leaking and fluctuations in valve body pressure when warm.i changed the fluid and filter a year ago but left the seals un disturbed. It was just a fluid change not a flush, the car drove so well until recently.
I have the typical harsh downshift from 2 to 1, which also tends to point towards valve body seals

Any thoughts and advice is hugely appreciated.

Cheers,
John

To add:

No fault codes in the EGS. Only some glow plug faults in DME, replacement glow module in the post.

@mods, can this thread be renamed please? ‘E60 520d engine vibration at idle’

Thanks...


I reset EGS adaptations, no change to the idling issue.
I disconnected the maf for the drive home.
No change, car was just a bit lifeless.

Tomorrow I will check engine mounts and the associated vacuum piping(active engine mounts). Also will check all other vacuum pipes that I can see.

I will also run more injector cleaner, although injectors look spot on in inpa... All rotational mass conformity values are well between +1 and -1

Update. I did a lot of city driving today and car was at its worst. In D at idle pulsating vibrations causing the whole car to slightly shuffle side to side, like as if the engine was hunting but the idle was steady. Vibration could be felt gently accelerating from a standstill until around 30kph or so.

After an hour or so cooling down outside I went back out to the shops with inpa connected. Checked all values and everything looked ok. Gear oil temp approx 70-75C. When stopped at the lights the pulsating vibration was gone it just felt again like a rough idle... however this completely went away if I moved the gear selector across to sport and manually selected 1st.
So it seems it’s happening when stopped in 2nd gear only. And it seem that it’s highly dependent or gear oil temperature or viscosity since it gets worse as it gets hotter.(car is perfect when cold)

Am I right in saying it sounds like a knackered torque converter or lockup clutch?

I will check fluid level in the coming days, may also try a friction modifier additive.

Quote:

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Originally Posted by John_D

Update. I did a lot of city driving today and car was at its worst. In D at idle pulsating vibrations causing the whole car to slightly shuffle side to side, like as if the engine was hunting but the idle was steady. Vibration could be felt gently accelerating from a standstill until around 30kph or so.

After an hour or so cooling down outside I went back out to the shops with inpa connected. Checked all values and everything looked ok. Gear oil temp approx 70-75C. When stopped at the lights the pulsating vibration was gone it just felt again like a rough idle... however this completely went away if I moved the gear selector across to sport and manually selected 1st.
So it seems it’s happening when stopped in 2nd gear only. And it seem that it’s highly dependent or gear oil temperature or viscosity since it gets worse as it gets hotter.(car is perfect when cold)

Am I right in saying it sounds like a knackered torque converter or lockup clutch?

I will check fluid level in the coming days, may also try a friction modifier additive.

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Have you driven another one John? Happy to compare mine if you want?

Quote:

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Originally Posted by 318 iS Cosmos

Have you driven another one John? Happy to compare mine if you want?

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I have not, but may take you up on the offer sometime if my head gets sufficiently melted :)

I remember how it was for the first year or so of ownership though, this is a new problem that has only manifested itself in the past few months so i have a good baseline for comparison.

situation update.. problem worsens with AC switched on, completely goes away if i select DS ,returns when i select D.

waiting for non-manky morning to do a proper inspection and fit the new TVD.

Cheers,
John

The symptoms seem to point more to an electrical or software issue as it looks like the mechanical functionality is working, albeit only in specific circumstances. It sounds like you need a really good diagnostician or auto electrician, otherwise head melting is almost guaranteed.

Gearbox oil/filter ever been changed?

Quote:

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Originally Posted by Roberto

Gearbox oil/filter ever been changed?

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About a year ago.

Replaced the vibration damper today.

Vibration still present after car warms up.

However, it seems to have changed a little bit I can’t put my finger on it. Engine much smoother and less rattly for sure.

I have more testing to do, bought a vacuum tester so next port of call will be vacuum pipes and engine mounts.

Happy to report that this is now solved.

The vibration was from the exhaust.
The rear silencer was vibrating which transmitted throughout the car.

The rubber hangers are worn( back left especially bad), allowing a tiny bit of up/down movement in the back box. I have temporarily fixed it by wedging something into a void in the rubber but have ordered all new rubber mounts.

The pulsing feeling when reversing slowly was the runout in my front brake discs causing uneven brake effort.

It’s nice to have a smooth idling car again and a very cheap fix.