Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Diesel Models: 190D
The system consists of an oil separator located under valve cover, distribution tube on intake manifold, and return flow tube. California models are equipped with a diaphragm regulating valve located in the oil separator.
When the engine is running, blow-by gases flow through the oil separator, through a connecting hose, and to the distribution tube on the intake manifold. Oil from the separator returns to the cylinder head through the return flow tube.
On California models, the diaphragm regulating valve is used to prevent excessive vacuum from forming in crankcase.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.