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DISTRIBUTOR GEAR WEAR |
Distributor Gear Wear On
GM 4.1L (HT-4100 Cadillac) Engines
Premature distributor gear wear has been noted on GM 4.1L (HT-4100 Cadillac) engines.
Since there is no direct lubrication of the distributor gear, General Motors has revised the gear to help eliminate this problem. The revised gear carries GM Part #10499813 and can be identified by a cut ring on the body section of the gear.
Since the cam bearing housing bores are fully grooved, AERA members have enhanced lubrication of the gear. Drill a small (1/32) hole from the groove of the last cam bearing housing bore forward toward the distributor opening of the cylinder block.
Inserting the distributor into the block can be of assistance in locating this hole.
The AERA Technical Committee |
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OIL PUMP DRIVE/DISTRIBUTOR GEAR |
Effect Of Oil Thickening On Oil Pump Drive/Distributor Spiral
Gear On Cadillac And Other Engines
It has been reported that oil thickening, caused by overheating,
can cause failure of the oil pump drive and distributor gears in
Cadillac and possibly other engines. On Cadillac, the
distributor gear set is lubricated by oil spray from the timing
chain.
Thickened oil reduces this lubricating spray and also imposes an
added load on the oil pump. Replacing the failed parts is only a
temporary remedy. To completely correct this situation, it is
necessary to disassemble the engine and clean it thoroughly.
The AERA Technical Committee
September 1972 - SPB 9
##END## |
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HYDRAULIC LIFTER UPDATE |
Hydraulic Lifter Update On
GM 4.1L (252 CID) HT-4100 Engines
A revised hydraulic lifter assembly has been released by General
Motors for the 4.1L (252 CID) HT-4100 engine used exclusively in
Cadillac automobiles.
The revised lifter assembly carries part #5234360 and features a
revised foot radius for improved service life. It replaces
lifter #5234235 for this engine only. The former lifter should
be used for the current 6.0L (368 CID) engine and all past model
V-8 gasoline engines used after 1968. Whenever lifter
replacement is called for on 4.1L (252 CID) engines, the new part
number should be substituted.
Aftermarket manufacturers have followed suit and offer the
revised component under the following part numbers.
Dana 213-1685
Pioneer Barnes VT-969
Sealed Power HT-969
TRW VL-73
Check with your aftermarket parts warehouse or distributor for
additional part numbers.
The illustrations below feature a representative aftermarket design of
the lifter. However, the ribs are simply used for identification and
may appear in different locations depending on manufacturer.
The AERA Technical Committee
December 1990 - TB 721
Please Destroy TB 334
##END## |
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CRANKSHAFT MAIN BEARING UPDATE ON HT-4100 ENGINES |
Crankshaft Main Bearing Update On
GM 4.1L (252 CID) HT-4100 Engines
Cadillac has updated the design of the main bearings for all 4.1L
(252 CID) HT-4100 engines.
The new bearings feature a slightly bigger wall thickness. The
#5 main bearing has been reduced in length from 1.029 to .982.
This was done to reduce the amount of oil at the rear seal by
providing a channel to direct oil away from the rear seal.
Several aftermarket bearing manufacturers have updated their
inventory to reflect the new Cadillac specifications.
The main bearing oil clearance can only be checked on these
engines with the cylinder heads and intake manifold installed and
torqued to specifications. Bearing oil clearances can differ
greatly between an unassembled and assembled engine. Overall oil
bearing clearance should never exceed .002.
(ITALICS ON)
For additional information see AERA Bulletins: TB 474R, TB 491 &
TB 702
(ITALICS OFF)
The AERA Technical Committee
October 1990 - TB 703
##END## |
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LOWER END KNOCKING NOISE ON HT-4100 ENGINES |
Lower End Knocking Noises On
GM 4.1L (252 CID) HT-4100 Engines
Some Cadillac automobiles equipped with 4.1L (252 CID) HT-4100 engines
may experience lower end knocking noises.
According to Cadillac, such a noise may be caused by interference between the cylinder block or piston and the first crankshaft counterweight (see illustration). Apparently later style crankshafts were produced with fully machined counterweights to eliminate interference conditions.
Transverse engines use crankshaft Part #1629092 while longitudinal
engines use crankshaft Part #1629093.
For additional information see AERA Bulletins: TB 474R & TB 491
The AERA Technical Committee |
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LOOSE INTAKE MANIFOLD BOLTS ON HT4100 ENGINES |
Loose Intake Manifold Bolts On
1982-83 Cadillac 4.1L (252 CID) V-8 HT4100 Engines
Oil consumption, excessive coolant loss and poor performance may be due to loose intake manifold bolts on some 1982-83 Cadillacs equipped with subject engines.
To cure the problem, carefully retorque the bolts. This is preferable to installing a new gasket because the new gasket will crush over time and lead to another loss of bolt torque.
If the intake manifold gaskets must be replaced, not that a restrictor in the center exhaust crossflow port is located on 1983 right bank gaskets. This restrictor is not required on 1982 engines.
When retorquing the bolts, the correct sequence and ft-lbs must be adhered to or engine distortion may occur. The sequence is shown below:
Bolt Tightening Sequence
1. Tighten bolts 1,2,3 & 4 in sequence to 15 ft-lbs (20.0 N·m).
2. Tighten bolts 5 thru 16 in sequence to 22 ft-lbs (30.0 N·m).
3. Retighten all bolts in sequence to 22 ft-lbs (30.0 N·m).
4. Repeat Step 3.
The AERA Technical Committee |
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CLICKING NOISE |
Clicking Noise On
GM 4.5 & 4.9L Engines
AERA members should be aware of a noise coming from the front of 4.5 & 4.9L Cadillac engines. The clicking or rasping noise may appear on new and remanufactured engines.
Improper clamping load of the bolts that attach the water pump pulley to the water pump has been found to be the cause. Excessive paint buildup in the threaded bolt holes of the water pump flange may prevent the bolts from achieving the proper torque. A single loose bolt may allow the pulley to wobble
slightly, resulting in the clicking noise.
Technicians should be instructed to remove the paint by running a tap down the threaded bolt holes of the pulley flange before mounting the water pump to the engine. Both original equipment and replacement water pumps may be affected by this condition.
The AERA Technical Committee |
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CAUTION INSTALLING CAMSHAFT SPROCKETS ON 7.0L ENG. |
Caution on Installing Camshaft Sprockets on
1977-1979 7.0L (425 CID) Cadillac Engines
AERA members have reported that the camshaft sprocket on 7.0L (425 CID) Cadillac engines varies in thickness.
When installing a camshaft sprocket on this engine, be sure to check the protrusion of the mounting bolts (Figure 1) at the back side of the camshaft sprocket mounting flange. If the bolts extend to far beyond the camshaft mounting flange, they may come in contact with the cylinder block which could lead to an undesirable engine noise.
Be sure to use the proper grade bolt should the OE mounting bolts need to be replaced. Torque all mounting bolts to OE specifications.
The AERA Technical Committee |
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FWD & RWD BLOCK & CRANK CHANGES ON 1980-87 4.1L EN |
Crankshaft & Cylinder Block Differences
On 1980-87 GM 4.1L (252 CID) Engines
AERA members have reported that there are two different 4.1L (252 CID) cylinder blocks and crankshafts being used for the Cadillac front wheel drive (FWD) and rear wheel drive (RWD) automobiles.
The following chart shows the differences in cylinder block and crankshaft for each application.
Component Casting # Applic'n Description
Crankshaft 1617590 FWD 6 bolt flywheel flange
1 piece rear seal
Crankshaft 1617590 RWD 3 bolt flywheel flange
2 piece rear seal
Cyl. Block 1625964 FWD 1 piece rear seal
Cyl. Block 1618864 RWD 2 piece rear seal
Note that both the FWD and the RWD crankshafts carry the same casting umber, but can easily be separated by their differing flywheel flange configurations.
Due to the difference in rear main oil seals and the quantity of bolts that attach the flexplate to the crankshaft, neither the cylinder block nor the crankshaft interchanges between FWD and RWD applications.
The AERA Technical Committee |
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VIBRATION FROM CRANKSHAFT REPLACEMENT |
Vibration Resulting From
Crankshaft Replacement On
GM (Cadillac) 6.0L (368 CID) Engines
AERA members have reported a severe vibration problem after replacing the crankshaft on the GM (Cadillac) 6.0L (368 CID) engines.
The 6.0L (368 CID) engine uses two different crankshafts, #1609142E and #1486424. These two crankshafts are not balanced the same way and are therefore not interchangeable.
The counterweights of the #1486424 casting are larger than the #1609142E casting. While there is a difference in the shape and size of the counterweights, the most significant difference between the two crankshafts is the design of the rear flywheel flange.
It is important to pay close attention to the casting number and flywheel flange design when replacing the crankshaft in GM (Cadillac) 6.0L (368 CID) engines.
The AERA Technical Committee |
