SUPERTECH inlet and exhaust valve stem seals Ford Mazda 2.5 L5-VE set of 16

Ford and Mazda engines concerned

This full set of 16 seals targets the Ford Duratec / Mazda MZR 2.5-litre 16-valve engine with 5.5 mm stems: L5-VE in the Mazda 3 (BL), 5 (CW), 6 (GH) and CX-7 (ER), 159 to 170 hp, then S7GA, S7GB, BGDA and BGDC in the Ford Transit Connect 2.5 and Kuga III hybrids, built since 2007.

Inlet and exhaust each count 8 valves on this block, and SUPERTECH caps every one with the same integral seal: the 16 pieces of the set therefore dress the whole head at once. Seated on the guide, each seal lets only the needed oil reach the stem.

SUPERTECH inlet and exhaust valve stem seals

In this twin-cam 2.5, be it in a CX-7 or a Transit Connect, the seal oils the 5.5 mm stem and holds back excess oil above the guide. With age and heat the lip rubber hardens and starts passing oil: the L5-VE's level drops between services, a blue haze shows when the engine fires or after a long stop at idle, and carbon coats 16 valves and 4 plugs.

SUPERTECH's VSI-D5.5E, an integral Viton (FKM) seal, matches the 11 mm guide and 5.5 mm stem of the 2.5 engine exactly. Made of 16 identical pieces, the kit covers inlet and exhaust in one job, with no sorting between the two rows.

Stem seal technical specifications

Stem seal installation

Technical guide

The brand offered

Working from San Jose in California for over 30 years, SUPERTECH designs race valves first, then the matching springs, guides and seals of its own. Ultrasound, X-ray imaging and laser measuring check each batch before reputed tuners sign it off on dyno and track.

Inlet or exhaust?

For the L5-VE, S7GA, S7GB, BGDA and BGDC codes, SUPERTECH sticks to a single item: its integral VSI-D5.5E in Viton (FKM) dresses the 8 inlet valves and the 8 exhaust valves alike, with a 5.5 mm stem and 11 mm guide everywhere. SUPERTECH rates this Viton at 204 °C (400 °F) continuous, welcome headroom on the exhaust. One set of 16 fits the whole engine.

When valve stem seals must be replaced

• The 2.5 burns oil and smokes blue as it fires up
• L5-VE head overhaul, valves removed
• All 2.5 guides renewed
• Stiffer springs or race valves fitted

Vehicle compatibility

FORD

MAZDA

Remember the uprated valves of the 2.5 L5-VE engine

Engine open? Check the 2.5's 16 valves too. On the exhaust side, SUPERTECH produces uprated valves designed for the L5-VE: