How to Test Brake Caliper Before Install


Old 11-28-14, 04:46 PM
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How to Test Brake Caliper Before Install

I'm replacing both front brake calipers on my 2004 Tundra and was wondering if it's okay to test for leaking piston seals using compressed air or a vacuum pump. I installed a new (remanufactured) Beck/Arnley caliper last weekend and one of the piston seals started leaking when I pressed on the pedal, so I'd like to test the caliper prior to starting. Seems like applying vacuum would be a good test because compressed air would move the piston regardless if a seal was leaking.
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Old 11-28-14, 08:16 PM
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I'm not a mechanic but I do all my own work so I'm just making some observations.

Usually rebuilt calipers are ok but I have seen them leak. Other then installing and bleeding them I don't know of any way of pre-testing them.

Usually the leak occurs as the piston extends outwards. It could be caused by a ripped seal or a scratch in the piston.
Old 11-29-14, 07:51 AM
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I'll extend the pistons a bit using compressed air (with wooden blocks inserted), then do a vacuum check and see what happens. "QC Passed" means nothing to me anymore.
Old 11-29-14, 08:05 PM
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You wont be able to put the pressure on it that the brake system does so you wont learn much.
Old 11-30-14, 06:47 AM
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Trust the QC sticker. This is not a perfect world. Sure one may not be right even though it has a QC sticker but two in a row is not likely. If the second one leaks I would look at installation as being the culprit.

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