SUPERTECH exhaust valve stem seals BMW M42 M44

BMW engines concerned

These seals fit the 6 mm stem exhaust valves of the 1.8 and 1.9 litre BMW 16-valve four-cylinders: the M42B18 from September 1992, when it moved to a 6 mm stem, then the M44B19. They are found under the bonnet of the E36 318i, 318is and 318ti Compact, the late E30 318i Convertible and the Z3 1.9i.

The cylinder head carries 8 exhaust valves, two per cylinder. The original seal surrounds the guide and meters the oil that lubricates the stem; BMW supplies it in seal set 11 34 9 065 438, valid for the 6 mm stem M42B18 and for the M44B19.

SUPERTECH exhaust valve stem seals

On the exhaust side of an M42 or M44, each seal sits right against one of the 8 hottest valves of the head. Once cracked or hard, it lets oil run down the stems into the chamber to burn there: you top up more often, the exhaust puffs blue and carbon clings to valves and ports. Yet the seal must not block everything, as a dry stem and guide wear fast.

For this job SUPERTECH uses Viton (FKM), a compound built to last despite the high temperature of exhaust valves. SUPERTECH states that this material is what makes them fit for strong heat, rated at 204 °C (400 °F) continuous. The seal sits on an 8.8 mm OD guide and hugs a 6 mm stem. The set of 8 fits the full exhaust of an M42B18 or M44B19; for the inlet, SUPERTECH sells polyacrylate (ACM) seals separately.

Stem seal technical specifications

Stem seal installation

Technical guide

The brand offered

Based in San Jose, California, for over 30 years, SUPERTECH builds valves, springs and guides, plus stem seals, for competition engines. Each new design starts as a finite element model, then gets tuned with respected engine builders on drag strips, rallies and circuits.

Why two different materials?

On the M42 and M44, the 8 inlet and 8 exhaust seals share identical dimensions, yet the exhaust valve gets much hotter. That is why SUPERTECH puts Viton (FKM), tougher when hot, on the exhaust (VS-VBM6-E) and keeps polyacrylate (ACM) for the inlet (VS-VBM6-I). Allow 8 of each.

When valve stem seals must be replaced

• Oil level dropping, blue exhaust smoke
• Cylinder head stripped for overhaul
• Valve guides renewed
• Fitting tougher valves or springs

Vehicle compatibility

OEM part number (BMW stem seal set): 11 34 9 065 438 (M42B18 from 09/1992, M44B19)

Remember the inlet valve stem seals

The inlet side wears at the same pace: use the strip-down to renew its 8 seals as well. For the M42 and M44, SUPERTECH offers: