Why does early timing chain stretching happen?
There are multiple factors contributing to this problem, not withstanding the 8 speed automatic transmission is one of the factors in my opinion. North American drivers prefer their cars to be automatic, in this case, the automatic is more economical, than the standard version which is preferred by the Europeans.
You may ask; Why is there a problem with the 8 speed automatic? The problem occurs with our driving habits and the programming of the automatic transmission. In normal ECO mode (the default mode) it will shift up quickly and efficiently to the highest possible gear to keep the fuel consumption at minimum, hence called the ECO mode.
4 Cylinder BMW N20 Engine
The quick up-shifting in daily driving will keep the engine’s rpm very low, which will cause the 4 cylinder engine to oscillate a lot more than would have been, if it driven on the autobahn at high rpm, where there are no oscillations are really present.
Naturally the chains, the guides are fairly weak design to make them light as possible. Our stop and go driving at low engine loads paired with an efficient automatic exacerbates the problem. Furthermore the extended oil changes also does not help to keep the whole thing properly lubricated for long life.
Needless to say the newer engines and their timing chains has been extensively redesigned to counter this common and often fatal problem.
In any case, if the chain makes noise it must be addressed immediately. All the components has to be replaced. For replacement, only an improved version available from the manufacturer. The replacement components must include the oil pump drive assembly as well, according to BMW repair instructions, also a revised, improved component.
There are multiple special tools required and attention to detail is essential to complete this rather delicate repair procedure properly and permanently.
You can see on the above photo a broken timing chain guard and a clogged oil pump pick up, which could be fatal to the engine.
In case you have any additional questions please don’t hesitate to ask. We are here to help. Thank you for your time and all the best.
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