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SALVAGED OEM ENGINE PARTS | Salvaged O.E.M. Engine Part Caution
More new engine components are being salvaged O.E.M. than ever before. O.E.M. production lines can save a block by custom fitting, for example, an oversize rod or main bearing. By doing so, an otherwise rejected part will be restored.
It does present a problem, however, when the engine is to be rebuilt. The unsuspecting rebuilder or mechanic will discover too late, that standard parts will not work. The unfortunate thing is that the engine has to be disassembled to find the problem and additional time spent in securing the special part.
To illustrate more specifically - the following situations have een brought to our attention:
1. Integral valve guides having oversize ID with valve stems oversize to match.
2. One or more replaceable valve guides with oversize OD.
3. All main bearing bores oversize and bearings with thick walls to compensate.
4. One or more valve lifter (tappet) bores oversize. Body of tappet is oversize to
match.
5. One or more rod and main bearings undersize ID to fit undersize crankshaft
journals.
6. Cylinder bores honed slightly oversize and fitted with special high limit
service pistons.
7. Push rods of varied lengths. (Must be identified and returned to their original
position).
8. A small quantity of cylinder blocks with deck height .030 lower than specified.
A special thicker head gasket was employed to compensate.
Summary: The best preventative action is to make no assumption that parts are going to be standard. The exceptions are small in number, but they do exist and must be considered. At times the blocks will be identified when special parts are used, but the mark of a good technician is still that he makes a thorough dimensional check and knows that the parts he installs match those originally used.
The AERA Technical Committee | |
VALVE STEM SEAL INSTALLATION | Caution On Installing Valve Stem Seals On
Chrysler, Dodge, Plymouth 5.2, 5.5, 5.8, 6.6 & 7.2L Engines
When installing intake valve stem seals in the subject engines, often the seals are crushed if the valve springs are excessively compressed during installation of valve keepers. Using the valve stem as a guide, the intake valve stem seals should be pressed firmly and squarely over the valve guides.
CAUTION: When installing valve retainer locks, compress the springs just enough to complete the operation. Do not force the seals against the top of the guides.
The AERA Technical Committee | |
FLYWHEEL RESURFACING CAUTION | Flywheel Resurfacing Caution
The AERA Technical Committee offers the following information regarding flywheel-resurfacing caution.
The clutch surface of the flywheel is a key bridge between the power generation source and the power transmission system. Problems that accompany the
flywheel into the shop fall into four major categories: Excessive wear, hard spots and metal discoloration, warping and runout. Below is a brief description of the four major categories.
1. Excessive Wear. Caused by grooves cut into the flywheel by a worn clutch
disc.
2. Hard Spots and Metal Discoloration. Caused by the slippage of the clutch
disc. The wasted energy transformed into heat causes nucleation and creation
of carbide hard spots in the flywheel surface. The heat caused by slippage
is localized in areas of the flywheel. Due to the mass of the flywheel acting as
a heat sink, localized heat of friction is drawn off rapidly which cools the hot
spots quickly and causes the to harden.
3. Warping. Caused by abnormal heating and cooling that a flywheel encounters.
This is accentuated by the fact that most of today's flywheels are made of
forged steel vs. cast iron. This forged steel, though more durable I subject to
greater warping due to its metallurgical makeup. A regular flat flywheel that
looks perfect may have .005-.010 dish.
4. Runout. May be caused by previously misaligned resurfacing methods. This
misalignment is most likely caused when the flywheel is resurfaced without
referencing the crankshaft flange.
SAE specification J618B notes that maximum runout for a flywheel surface is .0005 per inch of flywheel diameter. For instance if we had a flywheel with a
diameter of 13, take the 13 X .0005 = .0065 surface runout. Experience has shown that runout greater than .002 will most likely cause chatter and unbalance vibration. Excessive runout greater than .005 may cause severe vibration and self-destruction.
Flywheel grinders are used for resurfacing both flat and stepped (or recessed) flywheels. The flywheel machine achieves required flatness with minimum
amounts of material removed. Abrasive grinding processes will eliminate hard spots efficiently, creating a smooth and homogeneous surface. Alignment
or parallelism of the flywheel surface is maintained by referencing the crankshaft-mounting surface for the work piece. Critical centering of recessed flywheels is accomplished by using custom adapters or centering cones.
When confronted with resurfacing stepped or recessed flywheels, not only does the surfaces have to be parallel and correctly centered, but also the depth
relationship between steps must be maintained. Simply put, if .020 is removed from the lower step area, then .020 must be removed from the upper step area.
To assure that the correct dimension is to be used, measuring the clutch surface depth before and after grinding is done is recommended. Since grinding stones leave a radius on the corner of the clutch cover-mounting surface, squaring the radius to a perpendicular edge should finish the job. This will insure that the mating clutch pressure plate assembly will match up squarely when reinstalled.
The AERA Technical Committee | |
SPARK KNOCK (DETONATION) | Reducing Spark Knock (Detonation)
Chrysler Corporation has authorized a field fix for the purpose of reducing the possibility of spark knock (detonation) on 1979 passenger cars equipped with Federal 3.7L (225 CID) engines, 2BBL carburetor and automatic transmissions; and 1979 passenger cars and light-duty trucks equipped with 5.9L (360 CID) engines, 4BBL carburetor, California Emission Package and automatic
transmissions.
The recommendation is to change the timing as follows:
Passenger cars with Federal 3.7L (225 CID) engines -- From 12° to 8° BTDC
Passenger cars with 5.9L (360 CID) engines -- From 16° to 12° ± 2°
Light-duty trucks with 5.9L (360 CID) engines -- From 10° to 6° BTDC
After resetting the timing; idle set speed, propane idle speed, and hot fat idle speed should be checked and reset, if necessary, to conform to the specification on the vehicle emission label.
NOTE: It is mandatory that a new emission label be applied over the existing lain the engine compartment. Labels are available from your local Chrysler and Dodge dealers.
The AERA Technical Committee | |
OVERSIZE CAM BEARING HOUSING BORES ON VARIOUS ENG. | Oversize Cam Bearing Housing Bores on Various Engines
AERA members have reported finding oversize cam bearing housing bores on several engines during the past months. At times it is a single bore that is oversize, other times there are several oversize cam bearing housing bores in the same cylinder block.
AERA cautions members to pay particular attention to this area of the cylinder block during disassembly. It is recommended to measure each cam bearing housing bore or the outside diameter of each cam bearing as is it removed as part of the estimate process. This will prevent surprises on the assembly bench after the cylinder block has been machined to completion.
In most cases, these oversize cam bearings are not available from any source on an off-the-shelf basis. Custom fitting a standard bearing in an oversize bore can be accomplished by knurling or by plating metal onto the outside diameter of the bearing.
AERA recommends making your customer aware of the fact that his/her engine was manufactured with an oversize/nonstandard housing bore and the various procedures that can be used to overcome this problem. Some of these solutions may not be approved by OE, but have been proven to be successful in the field.
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 |
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