SUPERTECH bronze valve guides BMW M42B18

The BMW engine concerned

These guides fit the 16-valve cylinder head with 6 mm valve stems of the M42B18, BMW's 1.8 litre four-cylinder built from September 1992. It powered the 318i, 318is, 318ti Compact and 318i Convertible of the 3 Series E36, with an output of 140 hp.

Each of the 16 valves slides in a guide pressed into the cylinder head. BMW lists this guide as 11 12 1 735 533, with a 6.0 mm bore and two repair sizes, 6.1 and 6.2 mm; the repair guide has a 12.7 mm (+0.2) outside diameter. A single SUPERTECH part number serves inlet and exhaust: 12.6 mm outside diameter and 43.3 mm length.

SUPERTECH manganese bronze valve guides

Pressed into the head, the guide steers the valve stem straight onto its seat, lets stem heat flow into the casting and anchors the stem seal. Once it is worn the stem rattles: the valve leans, closes poorly and oil is drawn toward the chamber, bringing heavy oil use, bluish exhaust smoke and falling cylinder pressure.

For this kit SUPERTECH picked manganese bronze, a copper-rich metal machined to very tight dimensions. The brand says heat moves through it far more readily than through the sintered guides that come on the production line. They normally go in with reinforced valves. The kit holds all 16 guides of the head, a single reference covering inlet and exhaust.

Valve guide technical specifications

Valve guide installation

Technical guide

Our reinforced valves for this engine have a 6 mm stem:

Our brand

Based in San Jose, California, SUPERTECH has developed valves, springs, retainers and guides for competition for more than thirty years. Finite element calculations, ultrasonic, X-ray and laser inspection: each new part is validated with builders of dragsters, rally cars and circuit machines.

Manganese bronze

Copper forms the base of this alloy, to which zinc, manganese, aluminium and iron are added. What comes out is a tough metal that endures friction and corrosion for years, a common choice for bushings and similar heavily loaded guiding components.

When valve guides must be replaced

• Engine oil disappearing past the valve stems
• Uprated valves fitted to an aged cylinder head
• Cylinder head reworked for circuit sessions, sideways competition or stage events
• Complete overhaul of the whole valve gear

Vehicle compatibility

OEM part number (valve guide): 11 12 1 735 533 (repair guide, outside diameter 12.7 mm +0.2)

Important: these guides do not suit the M42B18 built before September 1992, whose valves have a 7 mm stem.

Remember the valve stem seals

New guides call for fresh valve stem seals: BMW kit 11 34 9 065 438, or SUPERTECH seals VS-VBM6I-16 and VS-VBM6E-16.