BMW Timing Chain Inspection: N47, N57, N20, N13, B47
In short. This guide covers checking the timing chain and tensioner on the diesel N47 and N57, plus the gasoline N20 and N13. The point of the check is to catch chain stretch and tensioner wear before cam timing deviation turns into synchronization faults and engine damage. Diagnosis uses three independent methods: acoustics at cold start, mechanical inspection with the valve cover and oil pan off, and live camshaft position data. Matching the check to a specific vehicle is done via the 17-digit VIN.
Coverage: Engines and Models
The stated scope of the check is four engines: N47, N57, N20, N13. Related articles and internal links additionally bring in the B47, which doesn’t appear in the topic title. That discrepancy is sorted out below, in the section on contradictions in the source data.
The companion profiles and symptom pages are tied to the F20, F21, F30 Sedan, and F31 Touring.
Cause: Why the Timing Drive Fails
The source names four factors that lead to timing drive damage:
- chain wear;
- tensioner wear;
- a clogged oil pickup screen;
- overdue oil changes.
The practical diagnostic takeaway follows straight from this list: the acoustic symptom and the camshaft position faults aren’t standalone failures—they’re consequences of timing drive wear.
One quantitative wear criterion is stated separately. The control unit compares specified camshaft position with actual, and deviation greater than 5° is considered critical. That parameter, not a subjective read on noise, is the objective line between “keep monitoring” and “time to tear it down.”
The physical mechanism by which a clogged oil pickup screen and overdue oil speed up chain wear isn’t explained in the source. The cause is stated exactly as the source gives it, with no added interpretation. The article treats the combination of 2A82 and 2A87 together as the classic chain failure on the N47.
Symptoms
- rattle after cold start;
- chain rattle (constant or progressing);
- camshaft signal fault.
Fault Codes
| Code | Meaning in this article | Meaning in related descriptions |
|---|---|---|
| 2A82 | timing chain fault, sign of stretch | “VANOS, intake” |
| 2A87 | timing chain fault, sign of stretch | “VANOS, exhaust” |
| 29F2 | listed among possible codes for chain damage | “ignition coil, cylinder 2” (ignition system) |
The source calls the 2A82 + 2A87 combination the classic case of chain damage on the N47.
The gap between the two readings is fundamental: it changes the order of work. Until cam timing deviation is confirmed, the VANOS codes and the ignition code can’t be treated as proof of chain stretch—they have to be checked against live camshaft position.
Diagnosis Without Disassembly
- Record the cold-start sound. Rattle within the first 2–5 seconds after startup is the primary acoustic indicator. The audio recording is the first diagnostic step, not a formality: it gives you a baseline to compare against on repeat checks.
- Read camshaft position in ISTA/INPA. Compare the specified value with the actual one. Deviation over 5° is critical.
Neither step requires removing parts, and both come before any repair conclusions. If the factory diagnostic software isn’t available, the source recommends going to a specialist shop—without live data, camshaft position can’t be checked.
Diagnosis With Disassembly
- Remove the valve cover. Measure chain stretch and tensioner extension travel.
- Remove the oil pan. Check for plastic shavings from the guides.
Teardown reveals what live data can’t: the actual geometry of the wear. Plastic shavings in the pan are direct confirmation of guide wear, not circumstantial.
Discrepancies in the Source Data
The article is internally inconsistent in four places. That matters in practice, because the reading you take determines the scope of work.
- Codes 2A82 and 2A87. The text presents them as timing chain codes and as the “classic N47 chain damage,” while the related descriptions list them as intake and exhaust VANOS faults, respectively.
- Code 29F2. It appears in the list of possible chain-damage codes alongside the others, while the related descriptions call it a cylinder 2 ignition coil fault. Its place in the ignition system rules it out as a direct sign of chain wear.
- Intervals. “Annual inspection after 75,000 miles without replacement” and “preventive replacement no later than 93,000 miles” aren’t delineated: where monitoring ends and replacement begins isn’t stated. Formally, these are two different actions with two different thresholds.
- Engine list. The title and the first part of the article name the N47/N57 and N20/N13; later sections and internal links add the B47.
The wording is given exactly as the source states it. Resolving these discrepancies without additional BMW documentation isn’t possible.
Repair
The scope of work specified by the source:
- chain replacement;
- replacement of both tensioners;
- guide replacement;
- camshaft sprocket replacement if needed;
- engine oil and oil filter change;
- camshaft position check in ISTA.
Torque specs for reassembly come from the manufacturer’s procedure: fasteners use prescribed values, up to 148 lb-ft, depending on the joint.
Tools
| Tool | Purpose and specs |
|---|---|
| ISTA/INPA | reading live data, comparing specified and actual camshaft position |
| Special camshaft locking fixture | holding the cams while working on the timing drive |
| Torque wrench | tightening to the prescribed torque |
BGS 1039 |
oil filter wrench, 3-3/8 in, 16-point, 3/8″ drive |
Proxxon MicroClick MC 200 |
torque wrench, 1/2″, range 30–148 lb-ft |
A clean oil service additionally calls for a filter removal tool, a drain pan for the used oil, and the prescribed torque values.
Prevention
- oil change every 9,300 miles;
- LL-04 oil;
- avoid short trips;
- let the engine warm up before loading it;
- after 75,000 miles without a chain replacement—annual inspection.
When to Go to a Specialist Shop
Without factory BMW diagnostic software, the source is direct: go to a specialist shop. The reason is simple—the central wear criterion is camshaft position deviation over 5°, and there’s no way to measure it without ISTA or INPA.
What Shop Practice Shows
The article contains no statistics on observation counts, so what follows below is only what the source itself supports.
The most common presentation at intake: rattle in the first 2–5 seconds after a cold start plus camshaft faults. The cheap part of diagnosis is acoustics and live data; the expensive part is removing the cover and the pan. The owner mistake the source names outright: overdue oil changes and short trips. A separate diagnostic error—issuing a verdict off a fault code without checking actual camshaft position.
FAQ
When should you replace the timing chain on a BMW N47?
As soon as chain rattle appears, a 2A82/2A87 code is logged, or camshaft position deviates—and no later than preventive replacement at around 93,000 miles.
What does it mean when 2A82 and 2A87 appear together?
By the article’s reading, that’s the classic chain damage case on the N47. But the related descriptions read the same codes as intake and exhaust VANOS faults, so until camshaft position is measured, the verdict stays preliminary.
Bottom Line
Checking the timing chain on the N47, N57, N20, and N13 rests on three levels: a recording of the cold-start sound, live camshaft position data in ISTA/INPA, and teardown with measurements of chain stretch and tensioner travel. The critical threshold is camshaft position deviation over 5°. Past that point—chain replacement, both tensioners, the guides and, if needed, the camshaft sprocket, with cam timing verified after reassembly.
The practical move: past 75,000 miles without a chain replacement, record the cold-start sound and read camshaft position. No diagnostic software? A specialist shop will pull that data.
Related Articles
Engine profiles: N47, N57, N20, N13, B47.
Symptoms and related checks: cold-start rattle; engine bay noise; starts and immediately stalls; jerking and rough running; white smoke from the exhaust; crankshaft sensor check; camshaft sensor check; fuel supply check; turbocharger check; coolant loss check.
Timing drive problems: chain wear, symptoms, and replacement scope on the N47, N57, N20, and B47.