Hi all, just discovered an air leak in the bottom header of the intercooler on my 855 AWD, from a small hole about 2mm diam. which appears to be something deliberately introduced during manufacture [NOT a stone hit!] and is in the centre of a circle marked on the header. It may be something that should be plugged and the plug has come adrift, but why is it there and what should it be plugged with? Has anyone had this problem before, do they know what why it's there, and what has been done to fix it?

The intercoolers have a "weep" hole to let any condensed oil drain out. This hole is there by design and is not to be plugged up.
When the turbo gets old, the internal oil seal will wear and increasingly more amounts of oil will be introduced to the intercooler. This oil only gets to the intercooler when the turbo is active. It will collect on the air guide/splash pan and cross over to the drivers side and drip on the garage floor.

Klaus
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I still miss my 164