BMW Engine Belts – Timing Chain vs. Timing Belt – Serpentine Belts and Replacement
This answer is applicable for many BMWs in addition to the one listed below.
car year: 2007
car model: X5 3.0si
I have two questions:
1) Does my 2007 X5 E70 have a timing belt or a chain?
2) How many other belts do I have on this car and which ones require replacement at 50,000 miles?
The N52 6-cylinder engine that is used in many of the later model BMWs (most non-turbo US models from the late 2000s on) uses a timing chain to drive the camshafts. The only US (and common gray-market) engines that BMW ever used a timing belt on were the M20 6-cylinder of the late ’70s, 80s and early ’90s (used in the E21 and E30 3-series models, and the E28 and E34 5-series models (320/6, 323i, 325e, 325es, 325i, 325is, 325ic, 325xi, 528e, 525i) and the M21 diesel used in the US 524td (and various Euro models) of the ’80s. All other US model BMW engines have used timing chains. The timing chains do not have a specific service or maintenance interval. However, we are beginning to see failures of the plastic timing chain guide rails (generally, over 150,000 miles … and certainly NOT every one), which then allows the chain to “slap around” a bit and make some noise.
Most later model BMWs (Early ’90s on) use the Serpentine style belts for the accessory drives. Two belts are typically used; one for the air conditioning compressor and one for the water pump, alternator and power steering. Many of the latest models use electric water pumps and electric boosted power steering. Therefore the belt would not run these accessories and these models often have just one accessory drive belt.
The N52 engine in your E70 chassis (X5 07 to current) X5 does indeed have an electric water pump. In this case, you will have just one serpentine accessory belt that runs the AC, alternator and power steering.
While first generation serpentine belts had a recommended service life of about 30,000 to 50,000 miles, the new generations carry recommended replacement intervals of about 80,000 miles. With these higher mileage replacement intervals, we also recommend replacement of the idler and tensioner pulleys.