REVISED: BROKEN CAM SENSOR CAM SHAFT RELIEF HOLE INSPEC.

MODELS AFFECTED: 1986-87 CENTURYS, LESABRES, ELECTRAS & RIVIERAS EQUIPPED WITH 3.8L (VIN CODES B & 3) V6 ENGINES

NOTE: This bulletin supersedes Bulletin 86-6-10A, dated May, 1986, which should be discarded.

If a broken camshaft sensor interrupter is encountered on one of the above engines, the following instructions should be followed for it's replacement:

I. Vehicle odometer registers more than 15 miles

o Install new camshaft interrupter Part No. 25531725.

o Install new timing chain cover and valve Part No. 12329552. The new cover has a built in thrust surface that limits forward movement of the camshaft.

o Inspection of the camshaft for a relief hole should not be necessary.

II Vehicle odometer registers less than 15 miles o Inspect the camshaft to ensure that the oil relief hole which runs parallel to the shafts center line and from the front to the back of the shafts rear bearing journal is drilled clear through. If it is not, finish drilling the hole through the shaft. Clean the hole, remove any burrs and reinstall it.

NOTE- Inspection of the camshaft for the relief hole can be accomplished by removing the timing chain cover, intake manifold assembly and valve lifters, and then moving the camshaft forward slightly. The hole should then be readily visible from the front side of the shaft. It may be necessary to rotate it 180 to view the opposite side.

o Install a new camshaft interrupter and timing chain cover and relief valve as indicated in Item I above.

Engines built after December 1, 1986, will be assembled with the new timing chain cover and interrupter and should not experience the breakage condition. Casting number on new cover is 25531877.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.