Mild hybrid braking noise - normal or fault?

[Fibrous]

Originally Posted by neilgorin

I think this is something they can only do on the v60 due to the DCT gearbox, on the conventional torque converter box on the 22 year v60 and the current xc60 and above it wouldn't work as there wouldn't be a way to totally disengage the gear.

Ah OK so it's a function that is on the V60, certainly not on the XC60. Can you switch it off if you wish?

[neilgorin]

No option to switch it off at all, other than to click the lever into manual mode if you want engine braking.

In general the options on the car are seriously lacking compared to the older 2019 car, but I think that's the half hearted programming effort of the AAOS system vs Sensus.

[nu11eaf]

Originally Posted by Sergeant Grumpy

Blimey…..freewheeling……not something I want my car to be doing to be honest..
As said before, can’t say I’ve ever noticed it on my V90, but there is no mention of freewheeling in the manual for late MY22……
I know the engine sometimes stops just before actually coming to a stop at lights etc…..but have never noticed this on the move when lifting off the accelerator at speed.

On my D5 the freewheeling (coasting) only activates when in Eco mode when you lift of the throttle. Engine still runs, the gearbox drive goes into coasting and symbol in driver display says "coasting" so it is like knocking it into neutral or dipping the clutch in a manual gearbox. Touching the throttle or brake re-engages auto gearbox again, coasting does not work when using pilot assist or cruise control.

This is different to the mild hybrid system of the OP's car that shuts engine down.

[neilgorin]

Yes, on this one the engine goes off totally almost whenever it's off throttle and over approx 30mph. Braking doesn't bring the engine back on, it's only if you touch the throttle.

It does it on cruise as well as when being "pedalled" along.

It's almost like a full hybrid where they've forgotten to fit the drive motor...

[Steve Plowman]

Originally Posted by neilgorin

I think this is something they can only do on the v60 due to the DCT gearbox, on the conventional torque converter box on the 22 year v60 and the current xc60 and above it wouldn't work as there wouldn't be a way to totally disengage the gear.

It also does it on the xc40 b3 mild hybrid.
I get a similar noise if it is freewheeling at about 47 and I touch the accelerator or the brake

[SSM]

Not sure this is the same thing but, we purchased a new XC40 mild hybrid about 2 months ago. Occasionally when breaking we get a weird groan/rumble from somewhere. It doesn’t happen all the time but is very annoying. We have had the dealership look at it but no luck so far. The latest from Volvo, after they said a software update would resolve it (which it didn’t) was that the noise was “operational”. Not sure what that means but has anyone else got a similar problem.

[neilgorin]

Yes that's the exact issue I had with mine and on two XC40 courtesy cars I had including an April 2024 model which had the same setup.

My car had an update applied early May and since then I've not had it do it in the 2500 miles since.

[SSM]

Originally Posted by SSM

Not sure this is the same thing but, we purchased a new XC40 mild hybrid about 2 months ago. Occasionally when breaking we get a weird groan/rumble from somewhere. It doesn’t happen all the time but is very annoying. We have had the dealership look at it but no luck so far. The latest from Volvo, after they said a software update would resolve it (which it didn’t) was that the noise was “operational”. Not sure what that means but has anyone else got a similar problem.

Thanks for reply, it seems some people get it resolved but others don’t.
Any idea how I get Volvo to actually resolve this?
The dealer seems pretty useless and Volvo just say it’s operational but there must be a reason for it or a component that’s faulty surely.

[neilgorin]

That was my argument, but it seems that the noise is caused by a pressure release valve that was operating at the wrong time, supposedly the software update fixed it. It sounded like a grinding noise or in some cases a "flatulent" noise.

The update that stopped it started 3.0 - the older software 2.whatever I could get it to do it at will in my V60 and the XC40s the dealer lent me.

It may be your car is on the old software and will update itself in due course. The version is somewhere in the central screen if you go through the options.

[watto64]

Originally Posted by Sergeant Grumpy

Blimey…..freewheeling……not something I want my car to be doing to be honest..
As said before, can’t say I’ve ever noticed it on my V90, but there is no mention of freewheeling in the manual for late MY22……
I know the engine sometimes stops just before actually coming to a stop at lights etc…..but have never noticed this on the move when lifting off the accelerator at speed.

Our XC90 as a coasting function when in eco mode, and the rate of acceleration as 2 tonnes freewheels down a hill is quite scary. The upside is some very good MPG.