SUPERTECH exhaust valve stem seals Ford 2.3 EcoBoost

Ford engines concerned

These seals fit the exhaust valves of Ford's turbocharged 16-valve 2.3 EcoBoost four-cylinder: Ford Focus IV ST 2.3 (N3DA, N3DB), Mustang 2.3 EcoBoost (C23HD0D, N38H, N48H), Explorer 2.3 (C23HDTX) and Everest II 2.3 (C23HD0D), 269 to 330 hp, from 2014.

The 2.3 EcoBoost carries 8 exhaust valves, the most heat-exposed in the head. The seal surrounds the guide and meters the oil lubricating each stem without letting it reach the chamber.

SUPERTECH exhaust valve stem seals

On the exhaust side, the 2.3 EcoBoost exposes its seals to the hot gas rushing to the turbine. A baked or split lip lets oil slip down the 8 stems: the 2.3's level falls between services, a blue cloud escapes at start-up, and deposits spread to valves, manifold and turbo. Yet the seal must still pass an oil film, otherwise stem and guide would wear quickly.

For this position, SUPERTECH makes the VSI-FECO20-E in a blue Viton (FKM), 4.35 mm inside and seated on an 11 mm guide. This Viton withstands 204 °C (400 °F) continuously according to SUPERTECH, the strength expected next to the exhaust valves, which see the highest heat. The set of 8 covers the whole 2.3 EcoBoost exhaust; the inlet uses part VSI-FECO20-I, sold separately, 4.18 mm inside and also in Viton.

Stem seal technical specifications

Stem seal installation

Technical guide

The brand offered

For more than 30 years, SUPERTECH has turned out racing valves, plus the springs, guides and seals around them, from its home of San Jose, California. Each new design is first simulated by computer, then handed to recognised tuners for drag, rally and circuit use.

Why two different materials?

On the 2.3 EcoBoost, inlet and exhaust both get a blue Viton (FKM) seal, but not the same one: VSI-FECO20-I on the inlet (4.18 mm inside), VSI-FECO20-E on the exhaust (4.35 mm inside). Do not swap them at fitting. Count 8 seals of each type for one engine.

When valve stem seals must be replaced

• Oil dropping, blue exhaust on the EcoBoost
• Complete 2.3 head rebuild
• Valve guides replaced
• Hardened springs or valves to fit

Vehicle compatibility

Remember the inlet valve stem seals

Inlet seals age as fast as exhaust ones: change all 8 at the same visit. For the 2.3 EcoBoost, SUPERTECH offers this set: