Exhaust valve stem seals Subaru EJ20 EJ25

Subaru engines concerned

These seals cap the 6 mm stem exhaust valves of the Subaru EJ 16-valve boxer engines: EJ20-GN, EJ20EMPI, EJ20G, EJ20U, EJ20X, EJ20Y, EJ205, EJ207, EJ255, EJ257 and EJ25DET. They are fitted to the Impreza, WRX and WRX STI, Legacy, Forester, Outback and Baja, from 116 to 400 hp, since 1991.

The 8 exhaust valves, 4 per cylinder head, each have their own seal on the guide, letting through only the oil the stem needs. For the EJ205 and EJ207, the Subaru part number of this seal is 13211AA050, 8 per engine.

FERREA and SUPERTECH exhaust valve stem seals

At the exhaust, this seal works beside the engine's hottest valve. Once split, it lets oil creep down the stem into the port, where it burns: falling oil level, blue smoke, carbon. Nor can it seal fully, as a slight oil flow keeps stem and guide from wearing.

FERREA and SUPERTECH agree on Viton (FKM) here. FERREA presents it as a heat-resistant compound, backed by an integral spring that holds the lip sealed on the stem and limits oil loss. SUPERTECH quotes 204 °C (400 °F) continuous for its Viton seals.

Stem seal technical specifications

FERREA VS1015*8: EJ20-GN, EJ20EMPI, EJ205, EJ207.

SUPERTECH VS-TS6E-8: EJ20-GN, EJ20EMPI, EJ20G, EJ20U, EJ20X, EJ20Y, EJ205, EJ207, EJ255, EJ257, EJ25DET.

Stem seal installation

Technical guide

Our brands

	It was in Florida, in 1978, that Daniel Urrutia and Horacio Ferrea launched FERREA; its Florida and Argentina shops design and machine valvetrain parts for racing, where resistance to heat and wear counts.
	SUPERTECH turned to competition valvetrains over 30 years ago in San Jose and refines its parts with respected engine builders, in drag racing, rallying and on circuits.

Why Viton on the exhaust?

Much hotter than its inlet neighbour, the exhaust valve calls for a tougher material. Both brands settled on Viton (FKM): 204 °C (400 °F) continuous according to SUPERTECH, whereas polyacrylate tops out at 177 °C (350 °F). Count 8 seals per side here.

When valve stem seals must be replaced

• Oil burning, blue exhaust smoke
• Valves out, cylinder head overhauled
• Valve guides being changed
• Reinforced springs or valves fitted

Vehicle compatibility

OEM part number (Subaru EJ stem seals): 13211AA050 on the EJ205 and EJ207, 8 per engine; 13211AA110, 13211AA100 and 13211AA120 on the EJ255.

Remember the inlet valve stem seals

Use the same job to renew the inlet seals too, which sit in the same heads. FERREA and SUPERTECH offer them for these Subaru engines: