TorqFix

Auxiliary belt replacement: BMW N51 (N51B30A, N52B25A, N52B30A, N53B25A, …)

Step-by-step auxiliary belt replacement for the BMW N51: 10 steps. What to remove, in what order, and what to check after.

Workshop procedure for BMW — the exact step sequence and torque figures, straight from real workshop data.

10 steps 8 engine codes

🧭 Before you start

Fits: platform codes 125I, |, 130I, 2.5I, 2.5SI, 3.0SI, XDRIVE, 30I, 323I, 325I, XI, 328I, 330I, 523I, LI, 525I, (155/160, KW), 528I, 530I, 630

  • Timing position: the crankshaft or camshaft is set and locked during this job
  • Special tools named: locking pin

Don't miss

  • At removal, mark the direction of rotation; when refitting ensure the drive belt rotates in the same direction

🔧 Engine codes this applies to

N51B30AN52B25AN52B30AN53B25AN53B30AN62B40AN62B44AN62B48B

📐 18 workshop diagrams for N51B30A

Real factory drawings for this job — timing marks, bolt locations and routing. Locked in the free view.

N51, N52(K), N53 belt — N51B30A · diagram 1
N51, N52(K), N53 belt — N51B30A · diagram 2
N51, N52(K), N53 belt — N51B30A · diagram 3
N51, N52(K), N53 belt — N51B30A · diagram 4
N51, N52(K), N53 belt — N51B30A · diagram 5
N51, N52(K), N53 belt — N51B30A · diagram 6
N51, N52(K), N53 belt — N51B30A · diagram 7
N51, N52(K), N53 belt — N51B30A · diagram 8
+ 10 more diagrams
🔒 18 workshop diagrams for this job Ask about your BMW N51B30A — free or sign up free to see the drawings

📋 Procedure

  1. Fit the ancillary drive belt
  2. Remove the tensioner locking pin
  3. Tensioner locking pin:
  4. Remove the fan cowling
  5. Turn the tensioner pulley clockwise to release the tension
N51B30A? Steps differ between engine variants — check this job against your exact car before you commit to it. Check my car — free →
  1. Lock the tensioner; use a locking pin
  2. Remove the ancillary drive belt
  3. Used belt:
  4. Note: At removal, mark the direction of rotation; when refitting ensure the drive belt rotates in the same direction
  5. Refit the fan cowling
Workshop diagrams

Ask TorqFix about your BMW N51B30A — it answers with the exact sequence for that engine and the workshop drawing for each step. First question is free after a 20-second sign-up, no card.

Ask about your BMW N51B30A — free → or sign up free to see the drawings

Other BMW procedures

Who makes these pages, and how

TorqFix was built by a mechanic — after a 2,700 km drive with five roadside repairs that no diagnostic tool could explain.

The figures on this page come from manufacturer workshop documentation and are shown as they are. The page is assembled automatically from that data — it is not written by an AI. The AI works in the chat, where it answers for your specific car. It writes nothing here.

Variants of the same model differ. Cross-check torque against the factory manual for your engine before final tightening.

Seen a figure that does not match your manual? Write to us — we correct it and note when. support@torqfix.com

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Workshop data on this page last updated 20 Sep 2026.