BMW N43 BUDGET ENGINE REBUILD
Of all the car manufacturers around, it would seem that BMW don’t enjoy the best of reputations when it comes to engine longevity with four-cylinder petrols. Well, they used to but over the last 20 years these units have had a number of issues. The 2007–2013 N43 is a case in point. This was the final development of the 2001 N42 16-valve unit and it was a technological marvel; all alloy, chain-driven DOHC, directinjection, Vanos variable valve timing, balance shafts and ECU-controlled oil pressure for example. These engines did away with Valvetronic variable valve lift as it was incompatible for this application but the unit is still fairly complex.
The N43 has a few problems and the main one is the plastic timing chain guides breaking up. Not only can this lead to the chain jumping but the broken bits can be mashed up in the sprockets and the bits sucked-up into the oil pick-up. This starves the engine of oil resulting in major damage to the crank and elsewhere – resulting swarf can also ruin the camshaft bearings as well as the balance shaft bearings and the engine can end up as a complete write-off and not worth fixing.
So, I bought a 2008 318i N43 engine for £20 from a local garage – one that had been replaced with a good used unit and chucked in the skip. I stripped it down to see how bad it was – the crank was in trouble but other than that it looked OK.
The object here isn’t to do a no expense spared rebuild but to do a
