Yaris hybrid knocking

Interslice

Herselfs yaris has developed a sort of knocking noise. It seems to kick in when you are braking and then as you accelerate off gain it gets alot queiter. You can barely hear it then over 50km/hr until you brake again and it sounds like some has tied a strip of rubber around the drive shaft and its knocking of the chassis, slowing down as the car does.
Best way i could describe it.

Its a 171 1.5 hybrid with 30k km on it, still under the 3 year comprehensive warranty, just about. Has anyone come across this noise before?

If it was a normal car i would have said it could be a cv joint but with the hybrid braking CVT and all that going on I'm not sure what it is at all!

Would an inspection for something like this be covered under the warranty?

bazz26

If it's not a wear and tear issue then it should be covered by the Toyota warranty. They will need to diagnose it first though.

colm_mcm

You’ll sometumes hear of the brake discs rusting on the hybrids from underuse.

zilog_jones

Interslice wrote: »

If it was a normal car i would have said it could be a cv joint but with the hybrid braking CVT and all that going on I'm not sure what it is at all!

The way the wheels are driven and the friction braking is the same as any other modern car. Regenerative braking is done by the same motor that can drive the wheels (in the transmission).

Sounds to me like a stone is stuck in the brakes, or something else braking-related is loose. I had one stuck between the dust cover and disc on one of the rear brakes a while back, it would consistently only start rattling around at lower speeds or when braking.

Interslice

So dropped it in to denis mahonys this morning. Still making the noise pulling in. Got a phone call then around 11 to say they couldn't hear any noise and could i pop around to show them. Went for a spin with a mechanic.. noise gone! Happy days. Must of been something stuck in the brakes a stone or whatever.

He said, not regularly but you can stick it in neutral and brake hard to help clear them. They do rust up a bit especially at the back. I thought it was interesting that they dont have a regular brake booster but rather a nitrogen cylinder so you still have boosted brakes when the engines off. Must learn a bit more about the tech in them. Didnt see an altenator belt the last day having a look under the bonnet for something making a noise...

No charge after all that which i thought was sound.

zilog_jones

Interslice wrote: »

He said, not regularly but you can stick it in neutral and brake hard to help clear them. They do rust up a bit especially at the back.

The caliper slide pins can seize causing uneven wear or constant rubbing - I'd suggest lubricating every couple of years. That's assuming the Yaris has discs on the back?

I thought it was interesting that they dont have a regular brake booster but rather a nitrogen cylinder so you still have boosted brakes when the engines off.

I don't think it's any different from diesels, as they don't create enough vacuum like petrol engines. Didn't know there was nitrogen involved though.

Didnt see an altenator belt the last day having a look under the bonnet for something making a noise...

There's no alternator - there are two motor-generators: MG1 which is used for starting the ICE or charging the traction battery (so no separate starter motor either), and MG2 which is either driving the wheels (independently or combined with ICE power) or doing regenerative braking. Power steering and aircon compressor are fully electric. 12V battery is charged from the traction battery (DC-DC convertor) when the car is running.