Volvo Anti-Drainback Valve Diaphragm - OE Supplier ML3Z6A606A

Inside the Volvo SI6 oil filter housing there is a small rubber valve that is designed to close down onto the oil drain when the oil filter is in place. This keeps oil inside the oil filter housing when the vehicle is off. This valve is also the reason you should always remove the oil filter first, when doing an oil change on your Volvo 6 cylinder engine.

When the valve becomes old and brittle from years of heat cycling, its sealing ability is reduced until eventually it allows the oil filter housing to drain while sitting. The resulting dry oil filter housing causes an extended period of time during engine start up where portions of the oil system is operating without oil pressure, causing increased engine wear.

Replacing the valve is simple, remove the oil filter and pull the tiny valve diaphragm out of the small lever bracket. If the old valve breaks apart, make sure to account for all pieces and remove them. The new valve simply pops in place with the extended rubber piece on the top pulling through the hole in the valve lever. A long pair of needle-nose pliers and some hand dexterity is recommended.

This part is made available as part of a TSB through Ford, so the packaging may be labeled as such.