Klifex Oil Filter Housing Anti-Drainback Valve

I had on-going P0011 issues. At some point, I realized it was the anti-drainback valve allowing the OFH to drain, which in turn led to low oil pressure on startup to the VANOS. Symptoms were the red oil light stayed on for a few seconds on each start (like a normal car would, after an oil change) and freeze frame of the P0011 showed it triggered at or right after startup.

Normally, one would just change to a new housing and change it again, when it fails. I am cheap and decided to try the anti-drainback valve replacement. I bought mine off ebay, from the Ukraine, for $30 shipped. Yes, the same one that is at war with Russia, but it still arrived in 9 days. It comes with a new OFH gasket also.



No instructions come with it in the box, but ebay listing (and the link above) showed a picture of using pliers to pull out the old unit, then installing the new unit, after lapping the plunger to seal surface. You reuse the spring from the original drainback valve. It's a really tight fit, so I ended up drilling sections of the original valve, until the rest of the old valve fell out. Original valve, mangled, but out of the housing:


Here you can see the grooves that the stock plunger eventually grinds into the housing, which is one of several reasons why it was no longer functioning:


The other issue with the stock design is that the plunger is too short. The Klifex design has a longer plunger which goes into a guide hole, keeping the plunger from dropping back in off-axis, when oil pressure is absent. Additionally, the replacement has wider plunger fins to spread the abrasive force of the plunger, as well as a better sealing surface shape.



If I remember. I'll report back on how well it's holding up.