BMW M20 Timing Belt replacement! A must do to avoid engine failure! The BMW M20 6-cylinder engine family uses a timing belt to drive the camshaft (as opposed to a chain or gears). These timing belts require periodic replacement in order to prevent breakage. Why not just wait until the belt breaks and replace it then? Well, the engine design is such that if the camshaft and the crankshaft do not turn precisely in-time, the valves in the cylinder head will hit the pistons This is known as an “interference” engine design. If the timing belt breaks, the camshaft will stop turning or come out of time with the crankshaft (and the pistons) we then have pistons and valves colliding, resulting in a minimum of a few bent valves. This requires that the cylinder head be removed and disassembled, and the damaged valves be replaced. This would be the GOOD scenario. Often, the damage will include broken rocker arms and even cracked rocker shaft journals or valve guides in the cylinder head. Of course, this means that the complete cylinder head must be replaced. The recommended replacement interval for the belt is 60,000 miles or 4-years. The 4-year mark is important for cars that do not see high mileage use. The belt will deteriorate over time, even if it does not have a lot of miles on it. If you do not know the mileage on the timing belt, we fully recommend that you replace it as soon as possible. You could be riding a literal time bomb. Common models that use these engines (that we see in the US) are: 320/6 and 323i through 82 (Euro gray-market), 325e, 325es, 325i, 325is, 325ic, 325ix through 91 (and 92 325ic), 528e. The timing belt replacement is not terribly difficult, but it does need to be precise. The Bentley or Haynes repair manual (for the applicable model), covers this task.
Posted on: Fri, 16 Aug 2013 20:13:57 +0000
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