Prod­uct Test: brake bleed­ers & fluid testers

10 sys­tems go head-to-head.

Car Mechanics (UK) - - Contents -

Re­peat­edly shout­ing in­struc­tions of “Up! Down! Hold! Pump quickly, push down and keep it there!” may get tongues wag­ging among the neigh­bours but will be fa­mil­iar to any­one who has had to coax an as­sis­tant to op­er­ate the brake pedal, while you at­tempt to purge ev­ery last air bub­ble from the brak­ing sys­tem.

Thank­fully, one-per­son bleed­ing sys­tems have negated the need to rope in a re­luc­tant vol­un­teer and are ideal for the home me­chanic. Aware that fully de­press­ing the brake pedal risks dam­ag­ing the mas­ter cylin­der seals, tool com­pa­nies have in­tro­duced tech­nolo­gies that pres­surise the brak­ing sys­tem via the fluid reser­voir, us­ing a spare tyre (such as Gun­son’s Eez­i­bleed), in­stead of a com­pres­sor that would fea­ture in a pro­fes­sional work­shop. How­ever, ap­ply­ing more than 20psi risks dam­ag­ing the hy­draulics and, be­cause most mod­ern tyres are in­flated to well over 30psi, you have to ad­just the pres­sure be­fore start­ing work. If ex­ten­sive re­pairs are re­quired, you risk flat­ten­ing the tyre fully and, un­less you have an­other one to hand, or can in­flate the tyre again eas­ily, you may be­come stuck. For­tu­nately, tool sup­pli­ers have recog­nised this and have de­vel­oped their sys­tems with hand-op­er­ated pumps, en­sur­ing that you will never run out of pres­sure.

The test pro­ce­dure

One litre of brake fluid, at most, was used to test each kit, all of which were sup­plied with a stan­dard 44mm cap, which tends to be the stock size for most mod­ern ve­hi­cles. Once in­stalled to the test car, the hand pump was op­er­ated to gen­er­ate an in­di­cated 15psi. The sys­tem was checked for leaks, prior to a rear caliper brake nip­ple be­ing opened, and fluid was ex­pected to flow for at least 30 sec­onds, without hav­ing to op­er­ate the pump again. We as­sessed how ef­fec­tively each kit topped-up the mas­ter cylin­der with fresh fluid au­to­mat­i­cally and checked if the reser­voir was over­filled af­ter­wards. We also mea­sured how much fluid re­mained in each kit, once the auto top-up func­tion stopped, to in­di­cate the de­gree of wastage.

While we have taken of­fi­cial prices into con­sid­er­a­tion, we re­searched a lower tar­get price and these brack­eted fig­ures are based upon those of­fered by cred­i­ble Uk-based re­tail­ers.

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