1986 Porsche 951 Bell Housing Ground Cleaning (Rev. 2)
Copyright © 2006, Tom M’Guinness
All rights reserved.
Bad ground wires can cause a host of odd drivability problems, including in particular the ground wires on the bell housing. These ground wires support a host of engine sensors, some of which are very sensitive to small voltage changes. The picture below shows the location of these two ground wires and their typical condition after 15 years or so on the road.
Next time you have the intake manifold off the car, it may be worth taking the time to clean up these ground wires. I find it easiest to first remove the heater hose (if the coolant is already drained for other work). Also, be sure to cover the flywheel inspection port -- a piece of duct tape as shown in the picture below will do. If you don't cover the inspection port, you run the risk of dropping one of the ground bolts or washers into the flywheel area. A wire brush on a Dremmel does a good (fast) job of cleaning the bell housing and ground straps (or just a piece of sandpaper). Running a tap in the bolt holes, and using new bolts and washers will help ensure a good clean connection. The picture below shows the same ground straps after cleaning.
