FAQ
TL;DR: Owner reports ~100 ml oil loss per 1,000 km and notes “You cannot hear or feel anything without a load when stationary.” Likely causes: crankcase ventilation (ODME) issues, turbo oiling, or pressure leaks at hoses/IC. [Elektroda, electro_Nick, post #16761992]
Why it matters: This FAQ helps VW Passat B5 FL AVF TDI owners quickly diagnose boost leaks and oil-in-intake problems without guesswork.
Quick Facts
- Reported symptom: ~100 ml/1,000 km oil loss with oily intake joints and parking drips. [Elektroda, electro_Nick, post #16761992]
- Boost leaks may not show at idle; they appear under load/pressure. [Elektroda, Jamrug, post #16762238]
- Primary suspects: ODME (engine vent), turbo passing oil; check both early. [Elektroda, Somebody22, post #16762236]
- Oil-fouled intercoolers can be rinsed and the whole intake washed, then dried thoroughly. [Elektroda, Somebody22, post #16767184]
- Excess oil in the intake can trigger diesel runaway; fix sources before hard driving. [Elektroda, Somebody22, post #16767184]
How do I find a boost leak if I only hear it while driving?
Pressurize the system and inspect hoses, the S-connection, and the intercooler end tanks. Leaks often appear only under load, so idle tests miss them. “You can’t catch it at idle.” Focus on joints that oil has softened. Replace any suspect couplers. [Elektroda, Jamrug, post #16762238]
I found a big hole (about 2–3 fingers) in the front turbo pipe—what next?
Replace the damaged charge hose and check adjacent clamps and brackets for rubbing points. Reinspect all lower “snakes,” since prior failures suggest systemic stress or oil-softened rubber. After replacement, road-test under load and recheck for fresh oil mist at joints. [Elektroda, electro_Nick, post #16766657]
Can I replace boost hoses without tearing down the whole front end?
Yes. Drop the front end into the service/working position to gain clearance. Inspect for causes of the hole, because oil degrades rubber. Correct any misalignment or interference that could abrade the new hose during boost events. [Elektroda, Somebody22, post #16766794]
Why is there so much oil in my intake even after turbo regeneration?
Two common sources are ODME (crankcase ventilation) and the turbo passing oil. Check the ODME valve and lines first, then verify turbo outlet for fresh oil film. Addressing both prevents repeat hose failures and oil pooling in the intercooler. [Elektroda, Somebody22, post #16762236]
What is ODME (odma) on a PD TDI?
ODME is the engine’s crankcase ventilation. It routes vapors into the intake. If restricted or failed, it increases oil carryover, wetting hoses and the intercooler. Fix ODME issues before blaming the turbo alone. [Elektroda, Somebody22, post #16762236]
How do I compression-test the AVF engine through glow plug holes?
Remove glow plugs and measure compression per cylinder. Repeat after adding a small amount of oil to each cylinder; a rise suggests ring sealing issues. Note: unit injectors on PD engines often leak, affecting results. [Elektroda, Somebody22, post #16766499]
Could a clogged intercooler cause overboost or leaks?
Yes. Oil can clog the intercooler and increase restriction. Rinse the intercooler and intake plumbing with extraction gasoline, then dry thoroughly before reassembly. “It is best then to wash the entire intake.” [Elektroda, Somebody22, post #16767184]
Can dirty turbo vanes make the AVF overboost?
Yes. Check the turbo’s variable vane mechanism. If the air guides are dirty or sticky, the turbo can overboost and stress hoses and the intercooler. Clean or service the vane assembly as needed. [Elektroda, AutoSerwis, post #16767253]
Is it safe to drive with oil leaking from the intake?
No. Excess oil in the intake can feed the engine and cause a runaway. Fix ODME and turbo oiling, clean the intercooler, and eliminate leaks before heavy load. This protects the engine and hoses. [Elektroda, Somebody22, post #16767184]
How do I rinse a Passat B5 FL intercooler safely?
- Disconnect both intercooler hoses and drain the collected oil.
- Flush the core with extraction gasoline until clear; do not shake violently.
- Allow complete drying before reinstalling, then clean connected intake pipes. [Elektroda, Somebody22, post #16767184]
What does “Oil Test” mean in this context?
A member suggests searching for an oil analysis/test to assess engine condition. Use it to check contamination or abnormal wear indicators while diagnosing intake oiling. [Elektroda, sk700, post #16766021]
Why can’t I hear leaks at idle on this TDI?
Boost pressure at idle is low, so weak joints stay sealed. Under load, pressure rises and opens small splits or loose couplers. Road-load or pressurize the system to find the leak. [Elektroda, Jamrug, post #16762238]
Six months after turbo regeneration, I still see oil at the ODME-to-intake valve—normal?
Some oil mist after regeneration can persist, but visible pooling or rapid hose failure is not normal. Trace the ODME line and valve for wetness, then reassess turbo outlet for fresh oil. The poster saw this six months post-regeneration. [Elektroda, electro_Nick, post #16767846]
What else could cause repeated hose failures?
Investigate interference and alignment near the charge pipes. Oil-softened rubber tears easily. Correct any misadjusted components that can rub or pinch hoses during engine movement and boost events. [Elektroda, Somebody22, post #16766794]
