Replacement Crankcase Vent Valve and Breather Hose Kit 121-050
Fits 1999–2006 models
$60.95
In stock
Air Intake
Crankcase Vent Valve
A crankcase vent valve controls how blow-by gases leave the crankcase and return to the intake to be burned. We list 2 crankcase vent valve and breather hose kits from $58 to $61 for 1999-2006 BMW models, including the 323i, 325xi, 328Ci, 330i, 525i, 528i, 530i, X3 and Z4.
Replacement Crankcase Vent Valve and Breather Hose Kit 121-043
Fits 1999–2006 models
$57.95
In stock
What the vent valve does
Some combustion gas always slips past the piston rings into the crankcase. The crankcase ventilation system draws these gases out, separates oil from them, and sends them back into the intake so they are burned instead of vented. The valve regulates crankcase vacuum. When it fails or its hoses crack, crankcase pressure and vacuum go wrong, which affects oil use, idle quality and fuel trims on these BMW six-cylinder engines.
Signs of a failed system
Common signs include increased oil consumption, blue smoke from the exhaust at startup, oil in the intake boot or throttle body, a whistle or rough idle, and lean codes. A strong suction at the oil filler neck with the engine idling, so the cap is hard to remove, also points to a failed valve or diaphragm. Oil leaks from gaskets can increase when the system cannot relieve pressure. Brittle plastic hoses often crack when you remove nearby parts.
Why buy the kit
These kits combine the vent valve with the breather hoses, because the plastic and rubber lines age at the same rate as the valve and often break during removal. Replacing them together saves taking the intake apart twice. Choose your year, model and engine, then check the fitment table. The job usually involves removing the intake manifold on these engines, so plan time for it and use new intake gaskets if yours are hard or flattened.
Crankcase Vent Valve questions
How do I test a BMW crankcase vent valve?
With the engine idling, try removing the oil filler cap. If it is very hard to remove from strong suction, or the idle changes sharply, the valve or diaphragm has likely failed. Check the hoses for cracks too.
Can a bad CCV valve cause oil consumption?
Yes. A failed valve can pull oil vapor and liquid oil into the intake, where it burns. That shows up as higher oil use, blue smoke at startup and oil pooling in the intake boot.
Do I need to remove the intake manifold?
On most of the six-cylinder engines these kits fit, yes, the valve and hoses sit under the intake. Follow your service manual and replace the intake gaskets if they are worn.