| The following technical bulletins were published by AERA. |
| | STUBBORN CAM CAP BOLTS ON 4.5L VIN N ENGINES | Stubborn Cam Cap Bolts On
1990-96 Infiniti 4.5L VIN N Engines
AERA members have expressed difficulty removing the
camshaft cap bolts on 1990-96 Infiniti 4.5L engines.
This difficulty raises concern when it is encountered
while attempting to remove the first bolt, as there
are a total of 48 bolts used. To compound this
problem, the bolt size is small and the bolt head is
an external TORX(R) type.
AERA members have reported socket breakage while
attempting removal, as these smaller tools have
limited integrity. Apparently, these bolts have taken
a set, as assembly torque of the bolts is a minimal
10 ft. lbs. These bolts had sealer applied at the
factory and, in some instances, excessive amounts may
have been used. This sealer is actually locking the
bolt shank above the threaded area and the head of the
bolt.
To facilitate removal of these bolts several methods
have been used. Using an impact driver and impact
socket has been the most effective. The impact driver
uses a shock method to break the bolt loose. Once
loose, removal is easily accomplished. One member has
indicated a sharp wrap with a hammer and blunt end
punch has worked for him. Of course, removing the bolt
head by using a grinding or end mill is also possible
for the most stubborn bolts.
Before installing the caps, position each camshaft so
their locating dowel pin is at the 12 o'clock
position. Then, install the camshaft cap mounting
bolts and torque them to 10 ft/lbs using the sequence
shown in the illustration below. Do not use any sealer
on bolt threads, use a light application of oil on the
threads and bolt head mating surface.
The AERA Technical Committee
April 1998 - TB 1558
##END## | | CYL HEAD INSTALLATION ON 93-96 3.0L VIN A | Cylinder Head Installation On
1993-96 Infiniti 3.0L VIN A Engines
The AERA Technical Committee offers the following information on cylinder head installations for 1993-96 3.0L VIN A engines. This engine uses two different length head bolts and one other small 6 mm bolt. For each head, one long bolt, seven short bolts and one 6 mm bolt are required.
Before installing the heads, place the number one cylinder at top dead center, making sure the crankshaft sprocket marks are lined up. Install the head gasket and cylinder head, then follow the procedure listed below.
1. Ensure bolt washers are installed on head bolts with chamfer
toward the bolt head.
2. Coat all bolt threads and contact surfaces with light engine
oil.
3. Install all bolts and hand tighten.
4. In sequence, tighten long and short bolts to 29 ft. lbs.
5. In sequence, tighten long and short bolts to 91 ft. lbs.
6. In sequence, loosen all bolts.
7. In sequence, tighten short bolts an additional 70-75^ turn.
8. In sequence, tighten long bolts an additional 65-70^ turn.
9. Tighten the 6 mm bolt to 106 in. lbs.
The AERA Technical Committee | | VALVE CROSSHEAD CLEARANCE | Valve Crosshead To Rocker Lever Clearance On
NH, NT & V-1710 Series Cummins Engines
Valve crosshead nose to rocker lever clearance on the subject engines must be checked during engine rebuild and at any time valve crossheads are replaced on engines using crossheads No. 123416 & 3000326. A minimum of .020 (.51 mm) clearance must be present as illustrated in Fig. 1, on the cylinder being checked with valves completely closed and crosshead in the upmost position. After installing rocker lever assemblies, check crosshead to rocker lever clearance as follows:
1. Turn crankshaft slowly in direction of rotation until the valves are closed on the cylinder being checked. With rocker lever held firmly against the stellite pad of the crosshead, a .020 (.51 mm) wire type feeler gauge must pass between the crosshead nose and the lower beam section of the rocker lever.
2. If the feeler gauge does not pass through:
a. Remove the rocker lever and/or crosshead and grind the nose of the crosshead or rocker lever beam in the area circled in Fig. 1 until enough clearance is obtained.
b. If the rocker is ground, grinding should cover the complete area illustrated in Fig. 2 in a continuous arc. Do NOT grind just the contact area.
Caution: A sharp depression in this area will cause a stress riser and eventual failure of the lever. Grind only enough material to achieve the required clearance. If grinding enters the oil passage, the rocker lever must be junked.
c. Grind sharp edges smooth.
The AERA Technical Committee | | | | | CRANKSHAFTS INDUSTRIAL |
Crankshafts Used In Industrial Applications On
GM (Chevrolet) 5.7L (350 CID) Engines
When the GM (Chevrolet) 5.7L (350 CID) industrial engine is used in some applications such as lift trucks, the only crankshaft that is applicable has the forging number 1182. Dimension A of the rear flange is slightly smaller than that of other crankshafts used in General Motors 5.7L (350 CID) engines.
The larger flange crankshafts will not pass through the center hole of the bell housing. This is very critical when an oil clutch system is used.
The AERA Technical Committee | | BURNED EXHAUST VALVES | Burned Exhaust Valves, Low Power & Hard Starting On
Cummins NH & NT Engines With Jacobs Brake 25B & 30
Cummins Engine Co. reported that if the following complaints are experienced in the NH and NT engines equipped with Jacobs brakes, the slave piston clearance should be checked:
A. Exhaust valve burning
B. Low engine power when at operating temperature
C. Engine hard to start or will not start at operating temperature
A standard slave piston adjustment of .018 +/- .001 has been established. The .018 clearance setting is a cold setting which results in zero slave piston to crosshead clearance when the engine is at operating temperature.
Should the slave piston clearance setting be less than .018, the following conditions outlined in A, B or C above may result as well as affect breaking power.
If the slave piston clearance is greater than .018 +/- .001, the following problems may occur:
1. Engine injector train component problems
2. Injector carboning
3. Bent injector push rods
4. Worn injector adjusting screws
5. Decreased camshaft life
6. Cam follower and follower shaft failure
7. Delay in breaking action
If the above problems are experienced and the engine is equipped with a Jacobs brake, the slave piston clearance should be checked with the latest Cummins specifications.
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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