| The following technical bulletins were published by AERA. |
| | ENGINE NOISE DURING START-UP ON JAGUAR 4.0L ENGINES | Engine Noise During Start-up On
1997-2000 Jaguar 4.0L V-8 Engines
The AERA Technical committee offers the following information regarding an engine noise during start-up for 1997-2000 Jaguar 4.0L engines. It has been reported that some engines may experience a rattling noise when the engine is started. The secondary timing chain tensioner may be the cause of this noise. Research has shown that a noise can originate at the chain tensioners to cause a resonance in another part of the engine.
A revised, spring assisted, secondary timing chain tensioner has been introduced to eliminate this concern, commencing at engine No. 98102106XX. In case of a customer complaint, the revised tensioners should be installed on earlier built V8 engines.
The installation of the revised tensioner, shown below in Figure 1, is the same as the original style tensioner except that it must be installed in the compressed condition (retained by the clip) as shown in Figure 2.
The retaining bolts should be tightened to the recommended torque setting 89-124 In/lbs (10-14 Nm) before the clip is removed to release the piston and tension the secondary chain. Note: tying a string to the clip before assembling the tensioner assembly may help recover the clip if it is accidentally dropped. It should also be noted that the tensioner for left and right banks have different part numbers, NCA2017AF for the A bank and NCA2017BE for the B bank.
The AERA Technical Committe | | REVISED CUMMINS SMALL CAM V8 CAMSHAFT & BEARINGS | Camshaft & Bearing Changes On
Cummins Small Cam V8 Engines
The Cummins Engine Company has introduced a revised camshaft and camshaft bearings for its V/VT-504 & V/VT-555 small cam engines.
The Cummins small cam engines carry a camshaft bearing housing bore of 2.187. The revised camshaft is no longer cross drilled and requires new camshaft bearings. The new camshaft bearings feature a wider groove and supersede all previously used bearings.
For V8 engines with 2.187 camshaft housing bores, use Cummins part #3278345 for positions 1 & 5. Use camshaft bearing part #3031037 for positions 2, 3 & 4. These new camshaft bearings may be used in conjunction with either the revised or the former design camshaft. Do not use earlier camshaft bearings with the late model camshafts.
The AERA Technical Committee | | CRANKSHAFT THRUST BEARING FAILURES | Crankshaft Thrust Bearing Failures
Crankshaft thrust bearing failure on vehicles equipped with automatic transmissions have mystified the engine and transmission rebuilding industries for quite some time. AERA has attempted to address these failures with technical bulletins as early as 1981. AERA bulletin numbers TB 229, TB 284 and TB 336 have all discussed these failures from different viewpoints.
Greg Boehm of Valley Transmission in El Cajon, CA with the assistance of Ed Hale have documented results of their investigation into the causes of crankshaft thrust bearing failures. AERA would like to extend its thanks to them for sharing their findings with us.
Early AERA bulletins attempt to relate the failure of crankshaft thrust bearings with the torque converter, but replacement of the torque converter does not always solve the problem. Similarly, replacement of the complete transmission or the crankshaft and bearings does not always solve the problem either.
Using a device that incorporated a port-a-power with a pressure gauge and a throw-out bearing, tests were performed on a V8 engine with a failed thrust bearing and a THM 350 General Motors transmission. It was determined that excessive forward pressure was being placed on the thrust bearing (150 to 300 lbs.). After disconnecting the torque converter, the pressure dropped to zero
and the crankshaft would run wherever positioned by the fixture with no forward pressure registering on the gauge.
Replacement of the torque converter, stator support, and input shaft did not reduce the forward pressure exerted on the crankshaft. Other areas of the transmission were checked, replaced or modified in an attempt to reduce the forward pressure on the crankshaft to no avail.
Pressure gauges were finally hooked up to the transmission cooler lines. The transmission output line (converter fill) had 100 lbs. of pressure while the return line (lube oil) only had 10 lbs. This indicated a restriction in the cooler or the lines to the cooler. Bypassing the cooler substantially reduced the forward pressure on the crankshaft. Further tests indicated a positive relationship between lube oil/converter pressure and forward pressure on the crankshaft. Reducing the lube oil/converter pressure to 30 lbs. at full throttle reduced
forward pressure on the crankshaft to nearly zero.
It is believed that excessive lube oil/converter pressure builds up between the front pump and the hub of the converter creating excessive forward pressure on the crankshaft. The bypass valve generally cannot vent this excessive pressure.
The AERA Technical Committee advises the following steps be taken when thrust bearing failure occurs:
1. Attach pressure gauges to the cooler lines to compare inlet and outlet
pressures. They should be very close to the same reading and be in the 20
to 30 lb. range.
2. If the cooler inlet pressure is substantially higher than the outlet pressure,
investigate for any restrictions in the lines or the cooler.
3. If the line pressure is within specifications, the transmission should be
checked for spline wear on the input shaft which may be causing bind and not
allowing the converter to properly move rearward on the input shaft. Other
areas of the transmission should be checked that directly contribute to
relieving pressures and/or building excessive pressures.
In addition to the mechanical items above that can be corrected, the vehicle owner should be advised to avoid lugging the engine in high gear, and to avoid prolonged climbing of hills in high gear especially with heavy vehicles or while towing trailers, other vehicles, etc. Working the engine and transmission hard in
high gear dramatically raises the lube oil temperature which can lead to transmission failures that may increase pressures on the converter. It is best to manually shift the transmission into a lower gear to decrease wear and tear on the transmission.
The AERA Technical Committee | | LOOSE VIBRATION DAMPERS ON AMC/JEEP ENGINES | Caution On Loose Crankshaft Vibration Dampers On
Some 1974-1976 American Motors V8 Engines
It has been reported that some 1974-76 American Motors V8 engines have been operating with loose crankshaft vibration dampers. If this condition is found, remove the damper and inspect its keyway, the woodruff key and the flat washer under the damper bolt.
If the flat washer is distorted or dished, it should be replaced. Both keyway and key damage can occur when an engine has been run with a loose vibration damper.
It is recommended that a worn damper, the key and the damper bolt be replaced, however, if the keyway in the damper is not worn the damper can be re-used.
When the damper is reinstalled, the crankshaft, crankshaft seal and the threads of the new damper bolt should be lightly lubricated.
Torque the damper bolt to 80-100 ft. lbs. (108.0 - 136 Nm).
The AERA Technical Committee | | VALVE STEM SEAL SUBSTITUTION CAUTION | Valve Stem Seal Substitution Caution
Over the years there has been much discussion on the type of
valve stem seal that is best suited for a particular application.
Rather than adding fuel to the fire, this article will attempt to
shed some light on the general purpose and use of valve stem
seals on today's engines.
Valve stem seals can for the most part be categorized into two
distinct groups. The first style of valve seal grasps the valve
stem and moves up and down with the valve, shielding the valve
guide much like an umbrella, deflecting lubricating oil away from
the guide. The second style of valve seal, commonly referred to
as a positive valve seal is firmly attached to the valve guide
and acts as a squeegee on the valve stem.
Whether your shop prefers to use the deflector type or positive
type valve seal should not simply be a matter of personal
preference or dictated by stock on hand. Valve seal
manufacturers consider the engine's configuration, such as
overhead cam, in-line or V8, gas or diesel and the intended
application, passenger car, heavy duty truck or stationary power
plant when selecting a valve seal. Additional design
considerations are the PCV system employed and the amount of
operating space between valve guide, valve spring retainer and
valve spring. Follow OE guidelines or the gasket manufacturers
application catalog for the proper valve seal.
Choosing a seal that is not designed for the application can
result in not enough oil entering the valve guide leading to
galling of the valve stem or valve guide or both. On the other
hand, an improper seal may also lead to increased oil
consumption. Either misapplication will result in a comeback and
customer dissatisfaction with the work you have performed.
The AERA Technical Committee
and
Fel-Pro Incorporated
March 1988 - SPB 154
##END## | | BEDPLATE INSTALLATION CAUTION FOR 4.0L JAGUAR ENGINES | Bedplate Installation Caution For
1997-2000 Jaguar 4.0L V8 Engines
The AERA Technical Committee offers the following information regarding a main bearing bedplate installation caution for 1997-2000 Jaguar 4.0L V8 engines. This engine uses three different bolt thread sizes used. If the improper torque is used on certain bolts, lower end failure of the engine could result.
Jaguar uses 34 bolts to hold the bedplate onto the cylinder block and there are 4 different bolts used. The bedplate is to be installed after piston and connecting rod assemblies are installed and all bolts MUST BE replaced after each use. To install the bedplate correctly, follow the procedure listed below and refer to Figure 1 below for the proper bolt locations.
Step 1 Install ?P" bolts and torque to 10-12 ft/lbs
Step 2 Install ?F" bolts and torque to 18-19 ft/lbs
Step 3 Install ?M" bolts and torque to 18-19 ft/lbs
Step 4 Install ?S" bolts and torque to 10-12 ft/lbs
Step 5-6 Torque ?M" bolts to 25-27 ft/lbs + 135°
Step 7-8 Torque ?S" bolts to 14-15 ft/lbs + 150°
Step 9-10 Torque ?P" bolts to 14-15 ft/lbs + 90°
Step 11-12 Torque ?F" bolts to 14-15 ft/lbs + 150°
Center-punch bolts after torque sequence is complete.
The AERA Technical Committee | | IMPROPER ROCKER ARM APPLICATION | Improper Rocker Arm Application On
GM 2.8, 4.3, 5.0 & 5.7L Engines
Close examination of rocker arm components is necessary when rebuilding cylinder heads on Chevrolet 2.8, 4.3, 5.0 & 5.7L engines. Retaining the correct rockers for the individual engine may save future warranty claims on premature valve train wear.
Once the rocker arm components have been removed, it appears that they are similar/like components. This is where the potential problem begins. They only appear to be the same or interchangeable. Chevrolet supplies a single part number for the V8 & 4.3L rockers, and a different part number for the 2.8L
rockers. There is significant enough difference in the angle between the rocker wear face and the rocker mounting hole to warrant two different rocker arms.
Original equipment rockers are marked (see illustrations below) before installation at the factory to aid identification. Also the contact wear face of the 2.8L rocker is narrower and the pivot slot is slightly longer than the V8 & 4.3L rocker.
Aftermarket suppliers may not have any identification marks or the marks may be different than the original rockers, leaving cause for possible confusion.
Intermixing of components at the time of rebuilding may lead to premature valve train wear, and possible warranty claims.
The AERA Technical Committee | | SURFACING CAUTIONS | Resurfacing 1978-85 Small Block Chevrolet V8 Cylinder Heads
Beginning in 1977, one of the changes Chevrolet incorporated into
its thin wall casted small block V8 cylinder heads was the angle
of the spark plug cooling port. A potential leakage problem
exists on these lightweight heads, especially when heavy or
repeated machining of the surfaces take place.
Fel-Pro Company engineers state that the walls of the cooling
port angle towards one another in pre-1977 heads (see Fig. 1).
This different angle increases the sealing area between the
combustion chamber and the spark plug cooling port whenever any
machining takes place.
Figure 2 shows the difference between the newer and older design.
The cooling port walls angle towards the combustion chamber on
the newer design. Machining the surface of this head reduces the
sealing area between the port and the combustion chamber, which
can lead to cylinder leakage.
It is recommended that AERA members do not take off more stock
than is absolutely necessary when working ont he newer design
head, and that a composition type gasket be used in place of a
steel shim gasket. A composition gasket offers more sealing area
than the protrusion bead on a steel shim gasket, making leakage
less likely to happen.
( insert Figures 1 and 2)
The AERA Technical Committee
January 1986 - SPB 128
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