carbonb build-up in intake manifolds

[Acruz]

Hello,

I'm in the process of doing a rebuild on my 89 Carrera with Wayne Dempsy's book + the Bently Manual .
While cleaning up before re-assembly I had noticed the carbon build up in the intake manifolds, particularly #1 & #4. Please refer to the attached photo. Your comments/diagnosis would be appreciated.

Thank you,
Alex

[Steve@Rennsport]

Hi,

Thats certainly not abnormal,.....

Its caused by blowby from the oil tank pushing oil fumes into the intake system. Now, you can see some of the uneven flow from branch to branch and why we oftentimes have the intake manifolds Extrude-Honed to match.

Did you perform a leakdown before the engine was disassembled?