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tractor Dave · 31-07-23, 06:13 AM

The piston and spring under the temp sensor is a pressure relief valve. As above, might be blocked or partially blocked. As it's below the filter housing the oil inside never gets drained during an oil change and crud will always sink to the bottom.

31-07-23, 06:13 AM	#3
tractor Dave Senior Member Classic Audi Club Member Join Date: Apr 2018 Location: Wales Posts: 1,174	The piston and spring under the temp sensor is a pressure relief valve. As above, might be blocked or partially blocked. As it's below the filter housing the oil inside never gets drained during an oil change and crud will always sink to the bottom.