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How-to guide

How to bleed Tektro hydraulic disc brakes

Bleed Tektro hydraulic disc brakes, common on e-bikes, with Tektro mineral oil using Tektro's caliper to reservoir method, with the bleed plug torque values from Tektro's own documents.

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Difficulty
Difficult
Time
45 to 90 minutes

Tektro hydraulic disc brakes come on a huge number of e-bikes, including its e-bike lines such as the HD-E350 and HD-E725. This guide follows Tektro's own bleed procedure, which pushes oil from the caliper up to the lever reservoir and out into a catch bottle or bag (Tektro bleed procedure). Tektro's owner's manual says to bleed after a hose is shortened or replaced, after the system was opened to air, or when the lever feels spongy (Tektro owner's manual). For the basics, see bleeding hydraulic disc brakes.

Brakes are safety critical. Tektro says to use only Tektro mineral oil, and that other fluids, especially DOT fluid, will harm the system (Tektro bleed procedure). Never mix fluids or share a kit with a DOT brake.

If a Tektro brake leaks oil, or the lever gives no resistance, stop riding and get it serviced (Tektro owner's manual). Test the brake in a safe place before every ride after a bleed.

What you need

  • A Tektro bleed kit (syringe, a short tube for the caliper, a longer tube with an M6 bleed bolt for the reservoir), see brake bleed kit
  • Tektro mineral oil, see mineral brake oil. Tektro dyes it red so it's easy to spot (Tektro FAQ)
  • The right bleed block for a 2 piston or 4 piston caliper, and the pad retaining pin
  • Torx keys (T15), hex keys (3, 4 and 5 mm), a 7 mm wrench for calipers with a bleed nipple, and a torque wrench
  • An empty bottle or plastic bag, rags, isopropyl alcohol, gloves and safety glasses. Tektro's manual says mineral oil can irritate eyes and skin (Tektro owner's manual)

Steps

1Put the bike in a stand and remove the wheel

Tektro has you unbolt the caliper (5 mm) and let it hang (Tektro bleed procedure).

2Step 2

Remove the pad retaining bolt (3 mm), take out the pads so oil can't reach them, and fit the bleed block and pin (Tektro bleed procedure).

3Step 3

Loosen the lever clamp (4 mm) and rotate the lever so the reservoir sits level with the ground (Tektro bleed procedure).

4Step 4

Fill the syringe about three quarters with Tektro oil and push out any air (Tektro bleed procedure).

5Step 5

Remove the caliper bleed screw with a T15, or loosen the bleed nipple with a 7 mm wrench, and connect the syringe with the short tube (Tektro bleed procedure).

6Step 6

At the lever, remove the reservoir bleed screw and thread in the long tube with its M6 bleed bolt, with the free end in the bottle or bag (Tektro bleed procedure).

7Step 7

Slowly push oil up from the caliper until it comes out of the reservoir tube clean and with no more bubbles (Tektro bleed procedure, Tektro owner's manual).

8Step 8

Close the caliper side, remove the reservoir tube and refit the reservoir bleed screw. Tektro lists 0.6 to 0.8 Nm for the reservoir bleed plug and 5 to 7 Nm for the caliper bleed plug (Tektro owner's manual).

9Step 9

Wipe everything with isopropyl alcohol, refit the pads (pad retainer bolt 0.8 to 1.2 Nm), and reset the lever angle (one piece clamp 6 to 8 Nm, two piece clamp 5 to 7 Nm) (Tektro owner's manual).

10Step 10

Refit the caliper and wheel, squeeze the lever to center the caliper, and tighten the caliper bolts. Tektro gives 6 to 8 Nm for M6 caliper bolts and 5 to 7 Nm for M5 (Tektro bleed procedure). See center a disc brake caliper.

11Step 11

If your lever has a brake cutoff sensor for the motor, check that it still cuts power before riding. Tektro asks for this after any adjustment (Tektro owner's manual).

If the lever is soft but nothing leaks

Tektro's FAQ blames a soft lever on low oil or air. Its fix is to hold the lever body level with the hose angled slightly down, pump the lever about 20 times to move air up, top the reservoir up to 80 to 90 percent and then rebleed (Tektro FAQ). See fix a spongy brake lever.

Common mistakes

Videos

How to Bleed Hydraulic Brakes, Tektro and TRP Flat Bar and Drop Bar Levers from Park Tool: a full Tektro bleed with Park Tool's mineral kit.

When to get a pro

  • The lever is still soft after a careful bleed, or oil seeps from the lever, hose or caliper.
  • The hose needs cutting or a new fitting.
  • You can't confirm the motor cutoff still works, see check brake cutoff and throttle.
  • Any doubt at all, see when to call a pro.

Sources

Stuck after these checks? Find a shop near you.

Need a pro?

If these steps didn't fix it, find a shop near you in our partner network. For battery or wiring trouble, look for shops marked Battery and electrical.

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