[bowser]

I have replaced a dozen or so front brake pads and rotors over the years and sort of thought I was pretty good at it until I did my 2006 S80.

All of the cars I have done were american and a few hondas but they all seemed alike. Just pull the calipers push the piston back, replace the pad maybe turn the rotors and reassemble.

But, when I did this on my S80 the brake peddle went way down, almost to the floor. I did not touch the hydraulic line so air was not my first thought. After running out of ideas I took it to the dealer because it is still under warranty. They said I had air in the lines. They bled the lines but still had a mushy peddle. They then said I "blew out" the master cylinder! How could that be?

Is there something different about a Volvo than say a Ford or a Buick?
There is one thing I did forget to do when making the repairs. I forgot to unscrew the resevoir cap. Some fluid did come out when pushing the pistons back.

Any help or suggestions for the next time appreciated. PS The dealer was great. They replaced the master cylinder under warranty!

Thanks,

 

[Dextrobrick]

Re: Problem with brake replacement job? (bowser)

Just like Ford, Buick, Honda, etc., Volvo uses the same type of hydraulic brake system as most every other automaker out there.

That said, one very special note to remember when working with ABS brakes--and this applies to all ABS systems regardless of brand--is to resist the urge to compress the brake caliper piston(s) back into each caliper during a brake pad change without first opening the brake caliper's bleeder screw to force the old and dirty brake fluid directly out of the system.

When a brake caliper's bleeder screw isn't opened prior to compressing the piston(s) back into the caliper, then all the old and dirty brake fluid inside the caliper will be backflushed under quite a bit of hydraulic force up right through the mighty expensive ABS control unit and then up into the master cylinder's brake fluid reservoir. This is also a great way to blow out old and weak seals in the hydraulic system.

Also since brake fluid is only good for about two years or so before it starts to naturally accumulate moisture build-up since all flavors of DOT-3, DOT-4, and DOT-4+ brake fluid are hygroscopic and will readily absorb moisture right out of the air and said moisture in brake fluid will readily boil leading to less than desirable and possibly catastrophic brake operation, the old brake fluid should definitely be flushed out and changed and the entire hydraulic system properly bled when the brake pads are changed. Just changing the brake pads while keeping the old and dirty brake fluid is really a truly half-arsed job since the brake pads are only as good as the brake fluid that's actuating them.

As always, when it comes to a car's brakes when in doubt...don't touch them.

 

[bowser]

Re: Problem with brake replacement job? (Dextrobrick)

Dextrobrick,
b
You were right on with this post. When I picked up my S80 from the dealer I talked to the service manager who told me that the rear seal was blown out and air was getting in the system as well.

I learned a lesson on this one. I will open the bleed screw when I press the pistons in. It's funny that of all the cars I have done brakes on I never had this happen, but they were all American except for a Honda. But then again what car is truly "American" anymore.

If you happen to come by this way again I would like ask where do I get a manual on a 2006 S80?

Thanks

 

[RearWheelPaul]

Re: Problem with brake replacement job? (bowser)

This isn't an issue if you change brake fluid annually.

I'm 18 years and counting on the same master cylinder and ABS pump. Replaced the seals in the brake calipers at the 15 year mark for safety sake -- even though everything was still working properly.

The moral of the story: Change the brake fluid often. Use a low hygroscopic fluid.