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CRANKSHAFT REPLACEMENT CAUTION FOR 1998-2003 GM ENGINES | Crankshaft Replacement Caution For
1998-2005 GM 4.3, 4.8, 5.3, 5.7 & 6.0L Engines
The AERA Technical Committee offers the following information on crankshaft replacement caution for 1998-2003 GM 4.3, 4.8, 5.3, 5.7 and 6.0L engines. Design changes in the flywheel flange thickness have been made to some crankshafts used in the above-mentioned engines. This bulletin is being re-published with additional information.
The later crankshafts are shorter on the flywheel flange as seen in the listing below. These changes are due to the many different vehicle / transmission combinations being built by GM.
A flywheel spacer ring GM Part #12563532 and a longer bolt set GM Part #12563533 is required when using a thin flange crankshaft to replace a thick flange crankshaft. Also, if the crankshaft is being used in a vehicle, which is a standard shift application, you also need pilot bushing GM Part #12557583 or 12479894.
Note: GM part numbers correct as of 12-18-04.
Years Liters Casting # Trans Flange Thickness
1998 early 4.3L 236, 255 V-6 1.62 thick flange
1998+up 4.3L 236, 255 V-6 1.500 thick flange
1999-2000 4.8L 312 V-8 M/T 1.250 thick flange
1999-2000 6.0L 215 V-8 1.250 thick flange
1999-2005 4.8L 482 V-8 A/T .857 thick flange
2001-2005 4.8L 482 V-8 M/T .857 thick flange
1999-2005 5.3L 216 V-8 A/T .857 thick flange
1997-2005 5.7L 216 V-8 .857 thick flange
2001-2005 6.0L 216 V-8 .857 thick flange
All GEN III crankshafts used in Camaro, Corvette and Firebird have a .857 thick flange and also have a freeze plug installed at the bottom of the pilot shaft hole. The 4.8, 5.3 + 6.0L don?t have the freeze plug. The drilled hole thru the centerline of the 5.7L LS1 & LS6 crankshafts allows a path to balance crankcase pressure within the lower crankcase. Doing so has eliminated possible oil consumption when the engine is operated over 4800 RPM.
Caution: Early crankshafts use a flat reluctor wheel and late have a recess. Recess will work on all years. Do not use a flat reluctor on late applications as it will cause an engine misfire.
The AERA Technical Committee | |
DISK BRAKE REFINISHING | Disc Brake Refinishing
Brake discs can be refinished if precision equipment is a available and a few simple rules are followed. The first thing to do is to determine which of the following will need to be done. Resurface-Recondition or Replace.
Resurface with a flat sanding disc (with disc rotating) if scoring is light or if the disc surface has severe rust scale.
Recondition if scoring is deep or if runout, thickness variation flatness and parallelism are out of specification. Scoring of the brake disc surfaces not exceeding .015 in depth, which may result from normal use, is not detrimental to brake operation.
Note: Both sides of the disc must be treated in the same manner. If one side
needs resurfacing or reconditioning the opposite side should be
treated in the same manner.
Replace if the disc cannot be reconditioned to bring it within specifications and meet the minimum thickness specification after reconditioning.
Remember: The number cast into the brake hub is a discard dimension not a refinish dimension. Note the following chart for each vehicle line:
Minimum Thickness Discard
Model After Reconditioning Thickness*
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Chevrolet 1.230 1.215
Monte Carlo & .980 .965
Chevelle
Camaro .980 .965
Nova .980 .965
Corvette 1.230 1.215
Vega .470 .440
Truck C-K-P 1.230 1.215
10-30 Series
* This dimension is past into the hub surface. Following is a picture story of the specifications as printed in the 1971 Chevrolet Shop Manuals.
All specifications are important and should be held even though must customer complaints will result from specifications as shown in Figures 6 & 7 not being within limits.
The AERA Technical Committee | |
NEW CYLINDER LINER O-RINGS | 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 COOLANT | 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 SPECS | 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 | 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 | |
OVERHEATING OF ENGINES WITH ELECTRIC COOLING FANS | Overheating Of Engines With Electric Cooling Fans
Ever since gasoline prices have shot up, vehicle manufacturers have downsized cars and their engines. One of the best ways of making a car smaller is to turn the engine sideways under the hood. This has instituted the use of one or more electric cooling fans to move air through the radiator. Diagnosing overheating conditions on engines with electric cooling fans requires a few extra steps to ensure that the electrical control system for the fan is operating properly.
o Perform all of the tests associated with normal
installations, for example: check antifreeze level,
thermostat, water pump and hoses.
o Check that the cooling fan is moving air through the
radiator. With the fan turned on air should never blow out
through the front of the vehicle. If there is more than one
fan, be sure to check both. It's possible for the
electrical leads to be reversed during installation causing
the fan to move air in the opposite direction.
o If the vehicle is equipped with two fans, be sure that both
of them work. If the vehicle is equipped with air
conditioning, one of the fans may only operate when the air
conditioning is on. Consult the service manual if you are
not sure.
o Fans are controlled by a temperature sending unit. Check a
suspected faulty sensor by bridging the two connections. If
the fan comes on, then the sensor is at fault.
o Verify that the fan comes on at the temperature listed in
the service manual. Replace the sensor if the proper
temperatures are not maintained.
For additional information see AERA Technical Bulletins: TB 706,
SB 158 & SB 137
The AERA Technical Committee |
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