Sunday, February 15, 2009

Wheel Cylinder Servicing

I spent the weekend servicing the wheel cylinders on my Peugeot 206. The rumbling noise from the rear drum brakes have become very annoying and I just had to take it apart to fix the problem.


If there is rumbling noises from the rear drum brakes, it could be because the brake pads are dragging on the drums, caused by a jammed wheel cylinder. The wheel cylinder is jammed because of rust caused by leaking brake fluid.

The Haynes Service Manual says that the wheel cylinder is not user serviceable, but I just didn't believe it. So I decided to try to service it myself.


Before opening anything, screw down the master cylinder reservoir cap onto a plastic sheet to obtain an airtight seal. This helps to minimise fluid loss when you open the wheel cylinder.


Remove the hydraulic pipe and cap the end to prevent fluid loss and dust getting in.


Remove the rubber boots. Slowly push out the pistons, making sure not to get any remaining fluid in the cylinder from splashing onto the bodywork. Remember that brake fluid can dissolve paint and corrode metal. Scrape off any rust and debris.


Use a rag to clean the insides of the cylinder. Make sure not to block the fluid inlet port and bleeder outlet port.


Check the pistons for wear and tear. If the rubber boots and cups are damaged, then buy a new wheel cylinder. If they are still good, clean them with suitable cleaner. Don't use water, because brake fluid absorbs water and will make the pistons rust.



Lubricate the pistons with brake fluid or suitable brake grease. Lubricate the cylinder too.

Once all is cleaned, reassemble everything, remove the plastic sheet from the master cylinder reservoir cap, bleed the brakes and adjust the parking brake.

After the servicing, the rumbling noise from the rear drum brakes are gone. But now there's a soft rumble coming from the from disc brakes. I suspect the front cylinders need servicing too. Well, that will be a job for another weekend.

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