Vaico is not a bad company, but Hengst OEM and Audi Genuine PCV's seem to cause the fewest issues. That's not to say it is definitely the PCV, but signs point to it. A leak in the vacuum or boost plumbing could also trigger your symptoms. I also like RPMTech147's idea about failed motor mounts as a possible cause and his test for the condition.
What is the condition of the crank case vacuum when the car is idling (is the oil filler cap hard to remove when the engine is idling)? Excessive crank case vacuum sucks down on that oil filler cap making it hard to remove - another sign of a bad PCV. When you remove the oil filler cap, does the engine run worse or stall (another indicator)? There are other tests for the PCV, including disconnecting the PCV-to-intake-manifold hose and temporarily plugging the hole on intake manifold side - search the forums and YouTube for this procedure and others. If you want to get deeper into the diagnostics you'll need a vacuum gauge and some time in the Factory Service Manuals and/or on the forums researching procedures.
Replacement of a bad PCV is very easy. There are videos online that will walk you through, step by step, if you want to save a couple hundred bucks in labor costs.
Dunno if it'll help, but here is info I found on the forum from member gcpogcpo that could provide better understanding of an oft misunderstood part:
Below is an extract from the dealer as to how the system works which they sent to explain why there will be vacuum. The extract notes that the system is designed to reduce the vacuum from 700mbar to approx. 40mbar.
Perhaps it is this part of the system not working properly and as such is not reducing vacuum as much as it should? At the moment we know there is vacuum but don't know how much?
An objective test would be to measure the vacuum to see whether it is in line with the design spec. I have read of some people making a vacuum gauge that is connected to the oil cap and which can then accurately measure the vacuum.
Has anyone else heard of such a device?
Dealer extract :
Crankcase breather system.
It prevents vapours enriched with hydrocarbons (blow-by gases) reaching the outside atmosphere from the crankcase. The crankcase breather system consists of vent ducts in the cylinder block and cylinder head, the cyclonic oil separator and the crankcase breather heating.
How it works:
The blow-by gases in the crankcase are drawn in by the intake manifold vacuum via:
- the vent ducts in the cylinder block,
- the vent ducts in the cylinder head,
- the cyclonic oil separator,
- the pressure limiting valve and
- the crankcase breather heating and then fed back into the intake manifold.
Cyclonic oil separator
The cyclonic oil separator is in the cylinder head cover. It has the task of separating oil from the blow-by gases in the crankcase and feeding it back to the oil system. A pressure control valve limits the intake manifold vacuum from approx. 700mbar to approx. 40mbar. It prevents the same vacuum forming as in the intake manifold and thus engine oil being drawn in via the crankcase breather or seals being damaged. To purge the crankcase, air is extracted from the clean air line (downstream of the air filter). The clean air then flows into the crankcase through a line connection on the fine oil separator.
During the development of the system the following objectives were pursued:
• Reduction in noise emission
• Improved engine idling performance
To reduce noise, a plastic coil was integrated into the pipe system. A high hydrocarbon concentration in the crankcase could impair the engine's idling performance. Idling performance is improved by the crankcase ventilation shut-off valve N548. This valve closes the vent line when the engine is idling if the oxygen sensor detects an excessively high hydrocarbon concentration from the positive crankcase ventilation system. The crankcase ventilation shut-off valve N548 is activated by a PWM signal ↗ from the engine control unit. It is fully open when de-energised ("fail-safe position” )
So, check the PCV and engine mounts using these or other procedures you discover, and please update this thread so future users can gain insight from your experience.
Reply With Quote
Originally Posted by MongoMcG
Bookmarks