928 S V8-4957cc 50L (1985) Intake Manifold Leak Checking Instruction
To perform the respective leak tests rationally, a plate can be made (drawing #1) which permits a 100% checkup for leaks on vehicles Type 928, 911
Turbo, and 924 Turbo. A different self-made tool will be used for the 922 and 924 (drawing #3).
Checking the 928 and 911 Turbo
Remove sensor late stop and install sealing plate and seal using the two screw points.
Pressurize system with air to 0.5 bar (7 PSI).
There is no need to seal the exhaust system since the engines usually stop in such a manner that at least 1 valve per cylinder is closed, so that the pressure
of approximately 0.5 bar obtained via sealing plate will not be reduced through exhaust system.
With pressure built up, larger leaks can be heard, slight leaks can be made visible by means of a leak detecting spray, which is non flammable and
non-toxic, or soapy water.