N63 engine reliability: strengths, watch-outs, and known issues

The first engine modifications caused a lot of trouble: rapid wear of bearings, peeling coating in cylinders, short life of timing chains, and even bursting spark plugs. However, it should be noted that all defective components were replaced under warranty without issue.

The majority of owner complaints on specialized forums are related to oil consumption. The culprits are usually stuck piston rings or hardened valve stem seals, but sometimes the cause can be a faulty crankcase ventilation system.

In some operating modes, this engine forces coolant out of the reservoir and it leaks directly onto the coils and injectors, which usually leads to serious breakdowns. Therefore, purchasing a plastic deflector to divert antifreeze is highly recommended.

The most problematic part of this engine is the short-lived fuel injectors; more than a dozen revisions were made before they became more or less reliable. Forums even describe several cases of hydraulic lock when starting after a long parking period.

The connecting rods of this engine are designed for stock power, but many owners decide to add a hundred or even more horsepower with inexpensive chip tuning. This often results in bent connecting rods, which can sometimes puncture the block.

Due to high temperature in the V of the block, oil often cokes in the turbocharger lines; the thermostat and auxiliary water pump have a not very high service life; and after 100,000 km, the Vanos and Valvetronic systems often require attention.