Workshop Journal: Gavin’s E46 M3 Engine Overhaul

We are often contacted by M3-owning enthusiasts wishing to give their car the impeccable service record that it deserves. Gavin was one such customer, wanting to give is 87k-mile 2004 E46 M3 an engine overhaul to not-only bring peak performance, but to futureproof it too.

Workshop Journal: Gavin's E46 M3 Engine Overhaul

Gavin enjoys his E46 M3 both on the road and on the occasional BMW Car Club trackday, and has gifted it with numerous OEM+ goodies from suspension enhancements to BMW Performance brakes and Recaro seats. The engine, up until coming to us, was untouched. Gavin decided to address the three main weaknesses of the S54 in one hit, requesting that we tackle the Vanos, head gasket and big end bearings.

Workshop Journal: Gavin's E46 M3 Engine Overhaul

As can be seen above, despite being a late car with the ‘improved’ BMW bearings and relatively low mileage, the bearings were in far from perfect condition. The crank was checked and within spec, so the bearings were replaced with King Racing coated items, with ARP bolts to boot. The perfect upgrade.

Workshop Journal: Gavin's E46 M3 Engine Overhaul

Gavin also supplied a set of Vibratechnics engine mounts, which we fitted during the work.

Workshop Journal: Gavin's E46 M3 Engine Overhaul

Onto the top end, which was stripped and had the head removed. Surprisingly, the gasket wasn’t showing any sign of failure, but of course was replaced anyway. The head was re-faced (needing only .004″), pressure tested, had the valves tested and was also fitted with new valve stem seals. It was then fixed back onto the block with ARP head studs and new gaskets/hardware throughout. The Vanos was rebuilt with our usual full compliment of Beisan Systems components including rattle repair, and Gavin also opted to have a Beisan Systems nylon upper chain guide fitted while the head was apart. The valve clearances were checked before the fluids were refilled (Castrol Edge 10w60 and new Genuine BMW oil filter, Genuine BMW coolant) and the engine could be fired for the first time.

Workshop Journal: Gavin's E46 M3 Engine Overhaul

Running flawlessly from the off, Gavin’s M3 could then be collected. Another happy customer.