Brake Failure

[PDP]

My son in law got into his V50 after it had been stood outside all night.
He had only driven a very short distance and was approaching a roundabout when he pressed the brake pedal and found it was solid !

He managed to return home, (down a small country lane which had no traffic) and immediately had the car taken to the Dealers.

After inspection they informed him that a "valve" had stuck in the brake system. Evidently, if the vehicle is parked for any length of time, pressure builds up in the system. When the vehicle is started, the valve releases the presssure and the system is OK. In this case the valve stuck and didn't release the pressure, resulting in lack of brakes.

He was informed by the Dealer that Volvo (UK) had had about "4 or 5 other instances of this valve fault".

He is a Traffic Police Officer and was very concerned about the fault. As he attends accidents, and is sometimes given the statement, "My brakes failed" he has tested brakes by pressing the brake pedal to see if there is pressure there. If the valve fails, there is brake pressure but the brakes are not working. HIs colleague in the Accident Investigation Dept. is also quite concerned about this, so if anyone else has had this fault, could you please let me know and I will pass the details on to him as he will be taking this up with Volvo UK.
Peter

[RedXC]

Possible from power brake booster

[skibo]

i don't know what 'valve' this might be - something to do with ABS possibly? I don't really know how ABS works, but I've always invisioned some sort of electronically controlled valve between the master cylinder and each brake caliber.

[gtm]

Possible from power brake booster

This is possible but I would be more inclined to think the master cylinder push rod is out of adjustment. I have seen this a few times with other cars and usually some miles on them.

The rod does not allow the m'cyl pistons to retract far enough to expose the reservoir feed port thus any pressure that may build in the system cannot be released. So technically it's not a check valve but a blanked port which has caused the problem.

I cannot say for certain if this has a vacuum boster but a quick check is to pump the brakes several times before starting then to apply pressure to the pedal. If the booster is working correctly the pedal will travel maybe 1/2"-3/4" as the engine builds up vacuum when started. If this uses a motor driven booster then I don't know if this is a valid check for I've not tried it nor read if is a correct test for that type of system.

Cheers,
GTM

[Reo]

If you balance weights are inplace and this does not occure whil braking or if it get worse while braking have you hubs checked for being out of round. Yes I said the Hubs not the rotors.

[Diesel is dangerous]

Dear Sir,

A few years ago a lady driving a 850 Estate lost all brakes and two children were killed in the accident caused by this failure. A judiciary inquiry demonstrated that the failure was known from VOLVO but no recall was issued. Volvo dealers had instructions to fix the problem as customers would bring in their cars for service. A criminal trial has taken place in 2006, in Alsace, France.

I thought this sad story might interst you.

Best regards

[chizel08]

My son in law got into his V50 after it had been stood outside all night.
He had only driven a very short distance and was approaching a roundabout when he pressed the brake pedal and found it was solid !

He managed to return home, (down a small country lane which had no traffic) and immediately had the car taken to the Dealers.

After inspection they informed him that a "valve" had stuck in the brake system. Evidently, if the vehicle is parked for any length of time, pressure builds up in the system. When the vehicle is started, the valve releases the presssure and the system is OK. In this case the valve stuck and didn't release the pressure, resulting in lack of brakes.

He was informed by the Dealer that Volvo (UK) had had about "4 or 5 other instances of this valve fault".

He is a Traffic Police Officer and was very concerned about the fault. As he attends accidents, and is sometimes given the statement, "My brakes failed" he has tested brakes by pressing the brake pedal to see if there is pressure there. If the valve fails, there is brake pressure but the brakes are not working. HIs colleague in the Accident Investigation Dept. is also quite concerned about this, so if anyone else has had this fault, could you please let me know and I will pass the details on to him as he will be taking this up with Volvo UK.
Peter

You will need professional assistance to replace your volvo brakes. Anything can happen to you if the brakes failed.. if the brakes failed through no fault of your own then you may be able to sue the manufacture for compensatory damages. They have an obligation to ensure their product is safe and won't cause harm.