1m9unqd¶

1 excerpts.

Reddit thread: Blown head gasket¶

reddit.com/r/SmartCar/comments/1m9unqd · p. 1 · Applies to: 451

Source: r/SmartCar (score 39, 25 comments) Topic: PCV valve / oil leak / blown head gasket misdiagnosis Models discussed: 451 Solution status: unclear

Problem: Mercedes quoted $6,400 to repair an oil leak initially suspected to be a blown head gasket. Vehicle was driven to 113k miles despite the leak.

Solution: Replace the PCV valve ($5 part). Multiple commenters (IAmEmIAmIAm, CasJrCorpus, SteveSteve71, Dreon718) confirmed PCV valve replacement as the likely fix rather than actual head gasket failure. SteveSteve71 provided detailed repair procedure: lower right side subframe bolts, remove intake manifold bolts and intake manifold to access PCV valve and hose; approximately 1 hour labor; top off oil and run engine until exhaust runs clean. whiteglove_stl noted PCV failure causes excess engine pressure buildup that can blow other seals.

Key facts: - Thread author received $6,400 repair quote from Mercedes for suspected blown head gasket - Multiple experienced commenters identified PCV valve failure as actual problem, not head gasket - PCV valve replacement costs approximately $5 in parts - Vehicle successfully operated for 113k miles with the leak using it as delivery vehicle - SteveSteve71 confirmed doing the repair on a 2012 451 pure with 225k miles total - PCV failure allows excess pressure buildup which can cause additional seal failures