2021 GTS 58k air oil separator failure
04-13-2023, 09:44 PM
#16
Rennlist Member
I looked at the oil vapor separator on my S tonight. Fairly tricky setup. It seems to also incorporate the canister purge line. The separator feeds the intake system both upstream and downstream of the turbo.
Two principal failure modes:
- unmetered air into the intake resulting in CEL and misfire - reported in this thread
- plug or clog resulting in excess crankcase pressure, collateral damage is a failed rear main crankshaft oil seal - reported on mbworld by owners of M17x 4.0L TT V8 owners
In my view replacement of the entire PCV system after warranty expires is a prudent step, to avoid the two principal failures, and to minimize intake valve deposits to the extent possible.
Posting for further understanding:
https://www.underhoodservice.com/tur...-system/Modern turbocharged engines have large oil separators typically incorporated into the valve cover or on the side of the engine block. The crankcase pressure is not managed by a simple check valve. Pressures are monitored electronically or mechanically at both the crankcase and intake. The system directs the vapors to either before the turbo or intake manifold when the time is right.
These next-generation PCV systems can fail because they are exposed to high temperatures and combustion gases that can damage plastic, flexible diaphragms, and seals.
If the system starts to leak, it can allow unmetered air to enter the intake. This can cause misfires and lean codes. In some cases, the pressure generated from the turbocharger can find its way into the crankcase if the system has failed. This extra pressure can cause oil leaks. If the pressure is great enough, it can even restrict flow coming from the turbocharger oil return line, thereby shortening the life of the bearings.
Two principal failure modes:
- unmetered air into the intake resulting in CEL and misfire - reported in this thread
- plug or clog resulting in excess crankcase pressure, collateral damage is a failed rear main crankshaft oil seal - reported on mbworld by owners of M17x 4.0L TT V8 owners
In my view replacement of the entire PCV system after warranty expires is a prudent step, to avoid the two principal failures, and to minimize intake valve deposits to the extent possible.
Posting for further understanding:
https://www.underhoodservice.com/tur...-system/Modern turbocharged engines have large oil separators typically incorporated into the valve cover or on the side of the engine block. The crankcase pressure is not managed by a simple check valve. Pressures are monitored electronically or mechanically at both the crankcase and intake. The system directs the vapors to either before the turbo or intake manifold when the time is right.
These next-generation PCV systems can fail because they are exposed to high temperatures and combustion gases that can damage plastic, flexible diaphragms, and seals.
If the system starts to leak, it can allow unmetered air to enter the intake. This can cause misfires and lean codes. In some cases, the pressure generated from the turbocharger can find its way into the crankcase if the system has failed. This extra pressure can cause oil leaks. If the pressure is great enough, it can even restrict flow coming from the turbocharger oil return line, thereby shortening the life of the bearings.
Last edited by chassis; 04-13-2023 at 10:46 PM.
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bobblehead (04-13-2023)
04-13-2023, 10:21 PM
#17
Racer
In my case, it was under warranty. I remember that the SA suggested that it be replaced every 60K.
My vehicle gets driven primarily on the highway, and I do tend to exceed the speed limit.
My vehicle gets driven primarily on the highway, and I do tend to exceed the speed limit.
The following users liked this post:
chassis (04-13-2023)
The following users liked this post:
chassis (04-13-2023)