SUPERTECH bronze valve guides BMW M50B25TU M52 M54

BMW engines concerned

The BMW M50 in its VANOS variable valve timing version (M50B20TU and M50B25TU, from September 1992), followed by the M52 (2.0, 2.5 and 2.8 litre), the M52TU and the M54 (2.2, 2.5 and 3.0 litre) are the 24-valve inline six-cylinder petrol engines fitted to the 3 Series (E36 and E46), 5 Series (E34, E39 and E60), 7 Series (E38 and E65), Z3, Z4, X3 and X5. The E36 M3 built for the North American market (S50B30US then S52B32US) use the same cylinder head.

Each of the 24 valves slides in a guide pressed into the aluminium cylinder head. BMW specifies a bore of 6.0 mm H7 for these guides and two repair sizes, 6.1 and 6.2 mm H7; repair guide 11 12 1 735 533 has an outside diameter of 12.7 mm (+0.2).

SUPERTECH manganese bronze valve guides

The valve guide centres the valve on its seat, transfers part of the stem heat to the cylinder head and carries the stem seal. When it wears, the valve rocks, seats poorly and lets oil pass along the stem: oil consumption, blue smoke and loss of compression.

BMW limits valve rock in its guide to 0.5 mm: beyond that, the guides must be replaced. SUPERTECH guides are machined to exact tolerances from manganese bronze, a copper alloy the manufacturer pairs with its low friction black nitrided valves for both performance and durability. The kit contains the 24 guides of one cylinder head, the same part number serving intake and exhaust.

Valve guide technical specifications

Guides supplied with a 5.98 mm bore, to be reamed after pressing in to the BMW size of 6.0 mm H7.

Valve guide installation

Guides are replaced with the cylinder head removed, by an equipped workshop: removal of the old guides, pressing in of the new guides, reaming to 6.0 mm H7, then checking each valve's contact on its seat.

Valve stem seals are replaced every time the valves are removed. SUPERTECH pairs these guides with its VS-VBM-I seals on the intake and VS-VBM-E seals on the exhaust.

Technical guide

SUPERTECH guides are designed to work with the brand's black nitrided valves, available for intake and exhaust on these engines.

Our brands

SUPERTECH, based in San Jose, California, has been designing valves and valvetrain parts for racing for more than 30 years, from drag racing to rally and circuit racing.

One part number for intake and exhaust?

Yes: SUPERTECH lists guide GDE-BMW-M50-EI for intake and exhaust. The kit of 24 therefore covers the 12 intake guides and the 12 exhaust guides of one cylinder head.

Should the guides be replaced with the valves?

New valves fitted in worn guides quickly develop play again. Checking valve rock, limited to 0.5 mm by BMW, shows whether the original guides can be kept or must be replaced.

When valve guides must be replaced

• Valve rock above 0.5 mm
• Oil consumption past the valve stems
• Fitting reinforced valves to a worn cylinder head
• Cylinder head rebuild on a track, drift or rally engine
• Complete valvetrain overhaul

Vehicle compatibility

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

Remember the stem seals

Replacing the guides goes with new stem seals. We offer the SUPERTECH seals matching these engines: