Hissing on brake pedal release

[Paradroid]

So this is a strange one. My 2020 C300 was in for a service and MoT yesterday. Got it back late lastnight and driving home there's a hissing noise when releasing the brake pedal. Noise still there there this morning and definitely doesn't sound normal, so called the dealers, they didn't do any work on the brakes so weren't sure what it could be.

From a read on here, sounds like a brake servo or booster? Is there a chance this could have been damaged by someone hitting the pedal a bit too hard, or is it likely just a coincidence?

Recovery due any minute...

 

[Paradroid]

Recovery was a really sound guy but he didn't think anything was wrong. It is a quiet noise to be fair, what do people think?
Video taken with audio system and ventilation off. Engine running and in D, so pedal pressurised

New video by Dorian Farrimond

photos.app.goo.gl

 

[ALFAitalia]

My son has those Jordans!!

 

[Paradroid]

My son has those Jordans!!

He's a man of taste, and young enough to be wearing them! I'm not, but IDGAF.

Well this brake pedal noise is turning into a non-event. Recovery guy had a listen and didnt think it needed recovering but did seem to think the pedal was a bit noisier than expected.

Anyway just been out again tonight for another test and it's fine now. Seems to have fixed itself.

Seriously got me thinking about the extended warranty though. I love this car to bits but it is a bit niggly

 

[optimusprime]

Sounds like rubber noise to me get a tin of silicone spray and give it the works in and around the pedal above .

 

[Scooby_Doo]

I release my parking brake,via the switch, when my car's in the garage, always a hissing noise on release (since new).
I took out the 2 year extended warranty , £700.00, Nox sensor replaced a few months ago + free diagnostics. Is it good value ? It all depends what goes wrong , how much do you value "peace of mind" , I'll probably pay for another two years when it runs out in March.
I normally change my cars before the warranty runs out so depreciation is on average £5-£6k per year so £350 a year for the extended warranty pales into insignificance. It doesn't cover everything , read the small print, but I now only cover 6000 miles per year and the car is now 5 years old.

 

[optimusprime]

I know there used to be a filter on the servo years back for the air . Dont use and silicone i can see now they have electronic system

 

[Paradroid]

Thanks for the help guys. I do think it must just be some grit or dust that affected it considering how quickly it went away. Funny timing that it happened just at the time of the extended warranty letter being sat on my desk haha.

Anyway I've gone for the warranty, bought 2 years this morning. I think the peace of mind will help me continue enjoying this car as much as I already have for the last 2 years. And I can't see myself changing it - it's one of those cars where a step up the ladder is going to be a big step financially. Even one step (C43) is big - second hand prices of those are very strong!

 

[Paradroid]

I release my parking brake,via the switch, when my car's in the garage, always a hissing noise on release (since new).
I took out the 2 year extended warranty , £700.00, Nox sensor replaced a few months ago + free diagnostics. Is it good value ? It all depends what goes wrong , how much do you value "peace of mind" , I'll probably pay for another two years when it runs out in March.
I normally change my cars before the warranty runs out so depreciation is on average £5-£6k per year so £350 a year for the extended warranty pales into insignificance. It doesn't cover everything , read the small print, but I now only cover 6000 miles per year and the car is now 5 years old.

That's interesting, so you've probably recovered around half the cost of the extended warranty already with that single repair, and still have the peace of mind for the rest of the term. I did read the small print and it really is a long list of exclusions. They seem to treat lots of items as wear and tear. Like the gearbox is covered but not the mountings.

One factor for me was the M264 engine in my car. We believe it doesn't have the known issues of the older M274, but it was new in 2019 so a bit early to be certain how it handles age and mileage.

 

[Smiley]

Keep an eye on it - a hissing noise on releasing the brake is most likely a leaking servo, which wants fixing before it gets worse.
If you have bought the MB extended warranty then you should take a close look at the terms and conditions - there is a VERY long list of exclusions and it definitely does not provide "peace of mind" imo. If you have only just bought it you may have a cooling off period - you may want to reconsider after you have looked at the exclusions.

 

[Scooby_Doo]

Keep an eye on it - a hissing noise on releasing the brake is most likely a leaking servo, which wants fixing before it gets worse.
If you have bought the MB extended warranty then you should take a close look at the terms and conditions - there is a VERY long list of exclusions and it definitely does not provide "peace of mind" imo. If you have only just bought it you may have a cooling off period - you may want to reconsider after you have looked at the exclusions.

I've just had another look at the "exclusions" and nearly all are wear & tear items or items that would be dependant on the "style" of driving.
I wouldn't expect to be covered for any of the exclusions.

 

[Smiley]

There are some exclusions that would surprise me if I thought that I had paid for "peace of mind" - for example the car overheating is not covered, no gaskets or seals are covered, no wiring or loom is covered, the list goes on - some of it is wear and tear but there are plenty of other exclusions - it does not compare well with other marque warranties

The list of exclusions is below:

Claims for mechanical or electrical failure of covered parts if the failure is due to wear and tear. Bodywork, body seals (including any convertible roof, boot, sunroof, doors and so on), fixings and fastenings (nuts, bolts, brackets, studs, clips and springs (other than suspension springs )), glass, interior and exterior trim, interior panels, paint, lamp units and wheels. Any failure that is caused by the insured vehicle overheating. This is not regarded as a mechanical failure under the terms of this insurance.

We do not cover the following parts. • Air cleaners • Any seal, gasket or sealant • Auxiliary belts • Batteries - non-HV and auxiliary batteries • Bonnet, boot and fuel-flap release cables • Brake friction material and discs and drums • Brake pipes and brake hoses • Clutch assemblies, clutch fork, release bearings, pressure plate and carrier plate • Clutch master cylinder and clutch slave cylinder • Core plugs • Distributor caps • Drive shaft and steering rack gaiters • Electrical connection blocks, terminals and fuses • Exhaust system, muffler, heat shields and exhaust pipes • Fuel filters • Gearbox, axle and drive line mountings • Handbrake and parking brake cables • Hinges • Hoses and pipes (non-metal), hose clips and connectors (not including coolant hoses) • HT leads • Light bulbs and LED bulbs (except xenon bulbs) • Navigation CDs, DVDs and SD cards • Oil filters and gaskets • PAS high-pressure hoses or pipes • Pollen and odour filters • Reprogramming or software updates unless these are needed as part of a repair to a covered part or will solve the complaint or fault. We will only pay for one hour's work • Shock absorbers and suspension struts • Spark plugs • Sunroof cables, convertible cables, convertible roof material and straps • Tyres • Wheels • Wiper blades • Wiring and wiring looms