BMW M62B46 V8: Oil Burning, the Timing Chain, and Longevity
At a Glance
The M62B46 is a 4.6-liter V8 from the M62 family, fitted to BMWs from the late 1990s into the early 2000s. It makes 347 hp and 354 lb-ft of torque, and it’s known for flexibility and silky-smooth delivery. The main weak spots are oil burning, the plastic timing chain tensioner, and head gaskets after overheating events. Kept on a maintenance schedule, it’s good for 186,000–249,000 miles.
The Problem
You get into the car on a cold morning, fire up the V8—and instead of a smooth burble you hear a diesel-style knock. A week later the oil level on the dipstick has dropped further than it should. Familiar territory for M62B46 owners.
This is one of the most interesting V8s of its era, but it punishes neglect. Here’s why it burns oil and breaks timing chain tensioners—and what it takes to cover 186,000–249,000 miles without a rebuild.
Symptoms
- Excessive oil consumption at high mileage
- Diesel-style knock after a cold start
- Rough running when cold
- Oil or coolant leaks around the cylinder head
- Unusual noise from the timing chain area
Causes
Oil burning comes from worn valve stem seals and piston rings. Over time they lose their seal, oil gets into the combustion chamber and burns. Let the level run unchecked and the damage can be serious.
The plastic timing chain tensioner goes brittle with heat exposure. If it fails, the chain can jump a tooth or snap outright—an expensive repair.
Leaking head gaskets are the consequence of overheating. The aluminum block and heads have different thermal expansion coefficients, so a heat event breaks the seal at the joint. Oil can migrate into the coolant and vice versa.
The diesel-style knock after cold starts is tied to a fouled throttle body and EGR valve. Carbon deposits disrupt their operation, which shows up as noise and rough running.
The Fix
Oil Changes
Change the oil every 4,700–6,200 miles. Capacity is 6.5 liters. Use only 5W-30 or 5W-40 oils meeting the Longlife-01 specification.
Checking the Oil Level
Check the level at every fill-up, or at least once a week. This engine’s appetite for oil means the level drops faster than on most motors.
Filter Changes
Replace the oil, air, and fuel filters every 9,300 miles. Clean filters are what keep the lubrication and fuel delivery systems healthy.
Throttle Body and EGR Valve Cleaning
Do this every 25,000–31,000 miles. It prevents the carbon buildup that causes the diesel-style knock. It matters most in city driving, with long stretches stuck in traffic.
Checklist for Buying a Used Engine
- Buy only from reputable sellers with a solid track record
- Ask whether the cylinder heads have been reworked—rebuilt heads with fresh gaskets are a plus
- Inspect the gaskets and valve stem seals—leaks are often visible to the naked eye
- Confirm the mileage and which ancillaries are included: alternator, starter motor, A/C compressor
The Bottom Line
The M62B46 is a strong, dependable engine—as long as you keep up with maintenance. Watch the cooling system and the timing chain; those are the most vulnerable assemblies. Change the oil on time, keep an eye on the level, and do the preventive cleaning, and the engine will cover 186,000–249,000 miles without a rebuild.
This engine is for owners ready to give it premium care. Cutting corners on V8 maintenance gets expensive fast. In return you get excellent performance, a distinctive soundtrack, and smooth operation.
M62B46 Technical Specifications
| Parameter | Value |
|---|---|
| Displacement | 4,619 cc |
| Power | 347 hp |
| Torque | 354 lb-ft |
| Bore | 3.7 in |
| Stroke | 3.3 in |
| Compression ratio | 10.5 |
| Octane rating | 95 |
| Oil capacity | 6.5 liters |
| Oil viscosity | 5W-30 / 5W-40 |
| Oil specification | Longlife-01 |
Unique Features
The M62B46 is the long-stroke version of the M62 family. The increased piston stroke with the same cylinder bore delivers more low-end torque—the engine is flexible and easy to live with day to day.
A combined injection system feeds fuel into the intake manifold and directly to the valves. That improves mixture formation across different load ranges and cuts emissions.
Massive balance shafts reduce noise and vibration—the V8 runs surprisingly smooth and comfortable.