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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 |
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REVISED CYL. HEAD TORQUES ON 1997-99 5.7L VIN G |
Revised Cylinder Head Torque Procedure On
1997-99 GM 5.7L VIN G Engines
The AERA Technical Committee offers the following information on a revised cylinder head torque procedure on 1997-99 GM 5.7L VIN G engines. This procedure should be used anytime the cylinder head is being installed and supersedes information found in 1997-99 service manuals. This engine has an aluminum cylinder head and block and is referenced as the LS1 or Corvette engine.
The reason this procedure has been revised is the bolt material has been modified, which allows additional clamping force. The 11 mm head bolts should be replaced at the time of cylinder head installation and the new bolts come with a pre-applied sealer and lubricant.
1. Tighten new 11 mm bolts (1-10) in sequence to 22 ft/lbs (30 N.m).
2. Rotate those bolts (1-10) in sequence an additional 90° turn using a torque angle meter.
3. Rotate only bolts 1-8 in sequence an additional 90° turn using a torque angle meter.
4. Rotate remaining 11 mm bolts 9 & 10 in sequence an additional 50° turn using a torque angle meter.
5. Apply a .200 (5 mm) bead of locking compound (GM P/N 12345382 or equivalent) to 8 mm bolt threads, and tighten bolts (11-15) in sequence to 22 ft/lbs (30 N.m).
Note: Do not re-use 11mm bolts.
The AERA Technical Committee |
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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 |
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CYL HEAD INSTALLATION ON 89-95 GM 5.7L VIN J ENG |
Cylinder Head Installation On
1989-95 GM 5.7L VIN J, DOHC Engines
The AERA Technical Committee offers the following information on cylinder head installation for 1989-95 GM 5.7L VIN J, DOHC engines. This engine is used exclusively in the Corvette ZR1 model. Previously, there has been limited information published on this engine.
GM has determined the cylinder head mounting bolts may be reused if they show no signs of stretching or thread damage. Follow the steps listed below and refer to the illustrations to follow the torque sequence while installing the head.
1. Make sure alignment dowels are correctly located in block deck.
2. Install head gasket over dowels onto block deck. Caution: Head gaskets are
specific to their proper bank.
3. Lubricate clean head bolt threads and washers with light engine oil. Install
bolts in proper locations and finger tighten.
4. Torque all bolts in proper sequence to 45 ft/lbs.
5. Torque all bolts in proper sequence to 75 ft/lbs.
6. Torque all bolts in proper sequence to 118 ft/lbs.
The AERA Technical Committee |
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IDENTIFYING ONE PIECE REAR MAIN SEAL CRANKSHAFTS |
Identifying One Piece Rear Main Seal
GM 5.0 & 5.7L (305 & 350 CID) Crankshafts
Identifying the Chevrolet 5.0 & 5.7L (305 & 350 CID) crankshaft used in various GM cars and trucks has not been made any easier since the introduction of the one piece rear main seal crankshaft.
Currently AERA is aware that casting numbers 14088526 and 14088535 are cast iron crankshafts used in either 5.0L (305 CID) or 5.7L (350 CID) engines. Again, GM is using the same crankshaft castings in two differently balanced engines. A steel crankshaft with the forging number 14088532 is used in the 5.7L (350 CID) Corvette engines.
Both engines are externally balanced and use the same counterweighted flexplate or flywheel and a non-counterweighted damper. Equally shared are the connecting rods which weigh 603-604 grams. The rotating (big) end of the connecting rod weighs 424 +/- 2 grams while the reciprocating (pin) end weighs
179 +/- 2 grams.
The weight for a 5.0L (305 CID) piston and pin is 646 +/- 3 grams, whereas a 5.7L (350 CID) piston and pin come in at 743 +/- 3 grams. The total bob weight for the 5.0L (305 CID) engine is 1815 grams in comparison to the 5.7L (350 CID) engine at 1916 grams.
AERA mrmbers have visually differentiated the crankshafts by the balance holes drilled into the front and rear counterweights. Machinists using these specifications should be aware that all of the measurements are approximate and may vary slightly from crankshaft to crankshaft.
The holes drilled in the 5.0L (305 CID) crankshaft front counterweight vary somewhat. There are either two 1 holes drilled to a combined depth of 2.563, or two similarly drilled 1 holes along with a third .750 hole drilled to a depth of
.125-.313. The rear counterweight is much the same with either two 1 holes drilled to a combined depth of 2.250, or two similarly drilled 1 holes along with a third .750 hole drilled to a depth of .188-.313
The 5.7L (350 CID) crankshaft's front counterweight has two 1 holes drilled to a combined depth of 1.188. The rear counterweight also has two 1 holes drilled to a combined depth of 1.563.
To-date visually separating the crankshafts using the specifications outlined above has been validated by later balancing.
The AERA Technical Committee |
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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 |
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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 |
