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Discussion summary
YOUR RESEARCH996T: Turbo oil drain/sump purpose?
Leading reported evidence
Fill sumps
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Suggestion
Another problem caused by the low position is that the oil would drain from the main oil gallery down through the turbo bearings when the car is not being used, this would fill the sumps then cause oil to enter the inlet.
Leading evidence: 'Fill sumps' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Fill sumps' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Suggestion
It's an output reservoir which i assume makes sure the Turbo cant run dry in any situation is my best guess .
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Suggestion
When the engine is running the oil pressure opens it so oil can flow to the turbo bearings.
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Suggestion · Original poster
Have seen quite a few turbo set ups over the years, but none with this tank/sump arrangement?
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Fill sumps
No successful repair reported for this finding.
0
Reported fixes
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Unsuccessful attempts
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Discussions
Read evidence and context
Discussions that contain suggestions
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Suggestion
Another problem caused by the low position is that the oil would drain from the main oil gallery down through the turbo bearings when the car is not being used, this would fill the sumps then cause oil to enter the inlet.
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911uk: 1 discussions
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Hi all, anyone know what the purpose of the oil tank/sump under the turbos on the 996T are? Have seen quite a few turbo set ups over the years, but none with this tank/sump arrangement?
It's part 8 in the diagram...
I have to admit i don't know the answer .. there is also very little info on it .. what i found is below ...
It's an output reservoir which i assume makes sure the Turbo cant run dry in any situation is my best guess .
Thanks for the detailed response! :thumb:
I really don't understand why they're there - especially when I believe the 996 GT2 and 997 Turbo don't have them?
Surely if it's needed for one, it's needed for all? :?:
They are there simply to collect the oil from the turbo bearings. Turbo bearings require no back pressure on their oil outlet, on the vast majority of engines the turbo is mounted high enough that the oil from the bearings can flow by gravity back to the sump without causing back pressure.
On the 996t the oil outlet from the turbos is below the level of oil in the oil tank due to their low position. The oil flows into the sump then is sucked out of the lowest pipe by a small pump located in the water pump housing, this pump returns it to the crankcase.
The upper pipe on the sump is a vent connected to the top of the main oil tank to make sure pressure or vacuum does not develop in the sump
Another problem caused by the low position is that the oil would drain from the main oil gallery down through the turbo bearings when the car is not being used, this would fill the sumps then cause oil to enter the inlet. To stop this on top of the turbo core at the oil inlet is a check valve. This is a simple ball and spring which takes a small amount of pressure to open. When the engine is running the oil pressure opens it so oil can flow to the turbo bearings. When the engine is stopped the spring pushes the ball back onto its seat which prevents the oil draining down.
So no you can't get rid of the sumps and the gt2 and 997 turbo do have them !
Mac
Great, thanks for the info!
Are there any other changes to the turbo set up that are unique to the 996/997 turbos apart from the oil sump and check valve? :?:
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