Trouble Shooting Crankshaft Grinding Problems


TROUBLE:  Chatter Marks - Regularly spaced marks.
     CAUSE:  General vibration.
     CORRECTION:  Tighten motor mounting bolts.  Check motor bearings and balance of motor.

     CAUSE:  Loose spindle pulley.
     CORRECTION:  Tighten pulley.

TROUBLE:  Regularly but widely spaced marks.
     CAUSE:  Bad driving belts.
     CORRECTION:  Replace belts.

     CAUSE:  Worn out idler pulley bearings.
     CORRECTION:  Replace bearings.

TROUBLE:  Long, regularly spaced chatter marks that form a checkerboard pattern.
     CAUSE:  Wheel out of balance.
     CORRECTION:  Balance wheel on wheel mount, repeat after trueing.  If trouble persists, run wheel without coolant to throw off excess water and store on side to prevent water from settling at lower edge of wheel.

     CAUSE:  Wheel out of round.
     CORRECTION:  True before and after balancing.  True sides to face.

TROUBLE:  Chatter marks have same frequency with building vibration.
     CAUSE:  Building vibration.
     CORRECTION:  Install mounting pads or move machine to different location in building.

TROUBLE:  Chatter marks fairly long, wide and evenly spaced at wide intervals and discolored; wheel glazed or loaded. 
     CAUSE:  Wheel too hard.
     CORRECTION:  Use softer grade or coarser grit wheel (also see Wheel Glazing).

TROUBLE:  Irregular chatter marks when using dead centers.
     CAUSE:  Work centers not true.
     CORRECTION:  Check fit of centers and lubricate point with white lead.

TROUBLE:  Chatter marks that form checkerboard pattern.
     CAUSE:  Faulty dresser.
     CORRECTION:  Replace worn-out diamond.  Tighten set-screw holding diamond.

     CAUSE:  Diamond cracked or loose. 
     CORRECTION:  Replace or reseat diamond.

     CAUSE:  Dresser not rigidly clamped to table.
     CORRECTION:  Adjust cam clamp.

TROUBLE:  General
     CAUSE:  Dressing
     CORRECTION:  Use sharp diamond rigidly held close to wheel.

TROUBLE:  Scratching of Work - Narrow and deep regular marks.
     CAUSE:  Wheel too coarse.
     CORRECTION:  Use finer grit wheel.

TROUBLE:  Widely spaced spots on work.
     CAUSE:  Oil spots or glazed areas on wheel face.
     CORRECTION:  Balance and true wheel.  Avoid getting oil on face of wheel.

TROUBLE:  Uneven marks on work.
     CAUSE:  Bad vee belts.
     CORRECTION:  Replace spindle belts.  Purchase set of six matched belts.

TROUBLE:  Fine spiral or thread on work.
     CAUSE:  Faulty wheel dresser.
     CORRECTION:  Replace cracked diamond; reseat diamond; use slower traverse speed; revolve diamond slightly every fifth dressing; tighten set screw on diamond.  Dress with less in-feed; do not allow diamond to stop while in contact with wheel; do not start dressing on wheel face.  Move diamond evenly across face of wheel; round off edges of wheel.

     CAUSE:  Sagging work.
     CORRECTION:  Provide additional steady rests.

TROUBLE:  Wavy traverse lines.
     CAUSE:  Ragged wheel dressing.
     CORRECTION:  Round off wheel edges.

TROUBLE:  Occasional deep marks.
     CAUSE:  Faulty wheel dressing.
     CORRECTION:  Replace worn out diamond; revolve diamond slightly; flush wheel with coolant after dressing.

     CAUSE:  Coarse grits or foreign matter in face of wheel.
     CORRECTION:  Dress wheel.

     CAUSE:  Bond disintegrates, grit pulls out.
     CORRECTION:  Coolant too alkaline for wheel bonding material; decrease soda content or change coolant.

TROUBLE:  Irregular marks.
     CAUSE:  Loose dirt settling on machine.
     CORRECTION:  Keep air and shop clean.  Clean machine daily.

TROUBLE:  Irregular marks of various lengths and widths; scratches usually fishtail.
     CAUSE:  Dirty coolant.
     CORRECTION:  Change coolant; clean coolant tanks, hose and wheel guard.

TROUBLE:  Deep irregular marks.
     CAUSE:  Loose wheel flanges.
     CORRECTION:  Tighten flanges; use blotters between mount and wheel.

TROUBLE:  Grit marks.
     CAUSE:  Wheel too soft or too coarse.
     CORRECTION:  Change wheel.

     CAUSE:  Dressing too coarse.
     CORRECTION:  Finer in-feed and slower traverse while dressing.

     CAUSE:  Improper procedure.
     CORRECTION:  Allow wheel to spark-out when finishing.

TROUBLE:  Grinding Grade of Wheel - Lack of cut; glazing, loading, burning of work; chatter.
     CAUSE:  Wheel acts too hard.
     CORRECTION:  Open up wheel grit by sharper dressing; 
     increase in-feed wheel pressure; discard gummy coolant; use coarser grit or softer grade wheel.  Increase work speed.

TROUBLE:  Wheel marks on work; short wheel life; wheel not cutting properly.
     CAUSE:  Wheel acts too soft.
     CORRECTION:  Decrease work speed and in-feed wheel pressure;
     dress wheel with slow traverse and less cut; change coolant.

TROUBLE:  Wheel Loading - Metal particles lodged on abrasive
grains or in wheel pores.
     CAUSE:  Incorrect wheel.
     CORRECTION:  Use coarser grit or more open structure to provide chip clearance; use more coolant.

     CAUSE:  Faulty dressing.
     CORRECTION:  Replace worn-out diamond.

     CAUSE:  Faulty coolant.
     CORRECTION:  Coolant too thick or heavy; change dirty coolant.

TROUBLE:  Wheel Glazing - Shiny appearance and slick feel.
     CAUSE:  Improper wheel.
     CORRECTION:  Use coarser grit or softer grade wheel or manipulate wheel to get softer grinding effect.

     CAUSE:  Improper dressing.
     CORRECTION:  Use sharp diamond; turn diamond 1/4 turn every fifth dressing; use faster traverse and deeper penetration.

     CAUSE:  Faulty operation.
     CORRECTION:  Use more in-feed.

     CAUSE:  Faulty coolant.
     CORRECTION:  Use less oily coolant; use more coolant; increase soda content if water is hard; don't use soluble oils in hard water.  NEVER use straight coolants.

TROUBLE:  Inaccurate Work - Work out of round.
     CAUSE:  Expansion of work.
     CORRECTION:  Keep temperature of work down by using more coolant and lighter cuts.

     CAUSE:  Work out-of-balance in machine.
     CORRECTION:  Correct with counterweights.

     CAUSE:  Faulty operation.
     CORRECTION:  Use less steady rest pressure.

TROUBLE:  Tapered journals.
     CAUSE:  Faulty grinding machine.
     CORRECTION:  Correct worn ways and alignment of tailstock and headstock; tighten headstock and tailstock spindle bearings; replace worn-out bearings; level machine.

     CAUSE:  Improper dressing.
     CORRECTION:  Check dressing fixture for rigidity; check diamond; move point of diamond closer to fixture.

     CAUSE:  Improper operation.
     CORRECTION:  Use harder wheel.

NOTE:  Machine MUST be level in all directions to insure accurate work.

TROUBLE:  Checking of Work - Work has check marks.
     CAUSE:  Improper grinding.
     CORRECTION:  Prevent wheel from acting too hard.  Don't force wheel into work; use more even flow of coolant; adjust idler to prevent belt slippage.

TROUBLE:  Burning of Work - Work shows discoloration.
     CAUSE:  Improper wheel.
     CORRECTION:  Use softer wheel; manipulate wheel to get softer effect; prevent glazing and loading; use more coolant; prevent chatter.

     CAUSE:  Faulty operation.
     CORRECTION:  Use less in-feed; eliminate belt and wheel slippage; prevent slippage of work.

TROUBLE:  Wheel Breakage - Radial break, three or more pieces.
     CAUSE:  Improper mounting.
     CORRECTION:  Use blotters between mount and wheel; correct uneven flange pressure; prevent dirt between mount and wheel.

     CAUSE:  Faulty operation.
     CORRECTION:  Prevent overheating due to lack of coolant or excessive wheel pressure on work.

     CAUSE:  Faulty grinding wheel.
     CORRECTION:  Sound wheel before mounting by tapping lightly to be sure that it was not damaged in transit or in handling.

TROUBLE:  Radial break, two pieces.
     CAUSE:  Flange too tight.
     CORRECTION:  Avoid excessive strains on sides of wheel.  Tighten flange as explained under Wheel Mounting.

                                                                         The AERA Technical Committee

                                      New Cylinder Liner O-Ring Seals On
                                      Cummins NH/NT 6 Cylinder Engines

Cummins Engine Company has released new O-ring seals for the cylinder liners in NH/NT 6 cylinder engines.  The new seals are made of an EP material and have a smaller diameter cross-section.

The new seal replaces both the old center seal #3008998 and the old lower seal #183049.  The new seal carries Cummins part #3032874 and is black in color with one blue dot.

The new O-ring seals are not to be intermixed with the former seals on the same liner.  Cylinder liner deformation will result.  You can use the former seals and new seals in the same engine as long as they are used in the correct combinations on each liner.  The illustration below shows the correct combinations.

                                                                       The AERA Technical Committee

                                               Oil in Cooling System on
                                         VW 1.5L & 1.6L Diesel Engines

AERA members have reported instances of engine oil in the cooling system on VW 1.5L diesel engines.  According to AERA sources, the problem is related to a crack in the cylinder head bolt hole located near the oil gallery feeding the cylinder head.

The oil feed gallery in the block is located on one side of the center head bolt hole and a coolant jacket is on the opposite side of the bolt hole.  Pressurized engine oil is diverted through a slot in the head gasket and is feed up the side of the head bolt to the cylinder head.  The oil also follows the bolt back down to the bottom of the bolt hole.  Should the crack in the head bolt hole extend to the coolant jacket, oil can mix with engine coolant.

This problem is generally found on engines equipped with 11mm head bolt holes.  Later design engines utilize 12mm head bolts and do not exhibit this defect.  At the time of this writing no successful repair procedure is available.

                                                                       The AERA Technical Committee

                                        Cylinder Head Specifications on
                                              Case 207 Diesel Engines

The following cylinder head specifications should be considered when remanufacturing Case Model 207 diesel engine cylinder heads.

The minimum cylinder head thickness has been established at 3.968 with a new head measuring 4.000 +/- .005.  Heads are measured from the deck surface to the rocker cover rail.

Valve recession should be checked and adjusted if necessary to a maximum recession of .015, below the deck surface, for both intake and exhaust valves.  Valves on new cylinder heads are generally flush with a +/- .005 tolerance.

                                                                       The AERA Technical Committee

                                         Main Bearing Saddle Repair Kits

The Cummins Engine Company has made main bearing saddle repair kits available for several engines.  These kits can be used to salvage cylinder blocks when a main bearing has spun and the main bearing saddle has been damaged.

Each kit contains an 1/8 drill bit, two hold down bolts (one for the lock ring and one for the other side of the saddle), a quantity of rivets and the appropriate number of repair sleeves.  Semi-finished or good used main bearing caps are also needed to complete the repair.

A main bearing saddle can be successfully repaired by following this procedure.
                                                                                                                            Remove the main bearing cap from the saddle to be repaired.  Using the appropriate align bore tooling remove .050 of material out of the saddle.  This will enlarge the main bearing bore by .100.

Clean the saddle and lock tang area.  Install the repair sleeve and align the lock tang slot of the sleeve with the one in the block.

From the repair kit, install the washer marked L on the lock tang side of the saddle.  Install the second washer on the opposite side.  Install the hold down screws and torque to 20 lbs.ft. (Figure 1).

Mount the 1/8 drill bit in a right angle drill, so that the drill extends 1/4 beyond the chuck jaws.

Using the 4 holes in the repair sleeve as a guide, drill through each of the holes into the saddle.  The proper hole depth is achieved when the chuck jaws contact the repair sleeve.

Clean the 4 holes and install the supplied rivets (Figure 2).  Peen the rivets until they are flush with the repair sleeve.

Remove the temporary hold down bolts and trim the ends of the repair sleeve so they are flush with the main bearing saddle.

Clean the main bearing bolt holes and install a good used or semi-finished main bearing cap.  Torque the main bearing bolts to specifications.

Using the appropriate align boring tools, refinish the main bearing housing bore to specifications.  Approximately .050 of material should be removed from the repair sleeve.
                                                                             
Main bearing bore repair kits or sleeves may also be available from several aftermarket sources.

                                                                        The AERA Technical Committee