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Cylinder head stress plate for Caterpillar 3126 diesel engines.
Engine Builders: The AERA Technical Committee offers the following information regarding a revised cylinder head stress plate for Caterpillar 3126 diesel engines. Previously AERA published Technical Bulletin 1561 concerning a stress plate for this engine.
The previously made plates covered a single cylinder and required multiple relocations of the plate to bore/hone all six cylinders. The revised stress plate covers all six cylinders and does not require removal until all honing operations have been completed. This stress plate should be used with a standard thickness head gasket with the cylinder head mounting bolts torqued to the values listed below.
Stress Plate Installation Procedures:
1) Verify the top of the cylinder block is clean, dry and free of nicks, burrs and is flat.
2) Torque all M20 bolts in numbered sequence to 99-121 ft.lbs.
3) Tighten large M20 bolts in numbered sequence to 305-335 ft.lbs.
4) Retighten large M20 bolts in numbered sequence to 305-335 ft.lbs.
As a reminder, it is also acceptable to install a repair sleeve for damaged or oversize bores on this engine. AERA is not aware of a company other than Caterpillar supplying this revised stress plate p/n 125-2064.
The AERA Technical Committee offers the following information pertaining to GM’s 5.7L VIN P LT1 engine. The 1992-’97 LT-1 engines employ a two-piece balancer (damper) and hub assembly. The damper is counterweighted and can be mounted to the hub in three different positions, two of which are obviously wrong.
When servicing these engines, to avoid vibration due to imbalance the damper and hub should be permanently marked before they are separated. If the damper is replaced, it should be matched for imbalance to the original and properly aligned.
If the crankshaft is accidentally rotated after placing alignment marks, position #1 cylinder at top dead center, then install hub with arrow on casting at the 12 o’clock position.
If the engine rotating assembly is not going to be balanced and a replacement damper is being installed, balance weights of the same size as used on the original damper must be installed in the same locations on the new damper.
The AERA Technical Committee offers the following information regarding low oil pressure after engine rebuilds on 1997-2002 Ford 4.2L VIN 2 engines. This condition may occur any time the oil pump screen and oil pan baffle have been removed and/or replaced.
These engines use either 6 or 7 nuts to secure the oil pan baffle to the lower portion of the main bearing caps (see Figure 2 and Figure 3). One of these 6 mm nuts must be installed after the oil pump pick-up screen has been installed and mounted to the cylinder block. If the mounting bracket is installed over the oil pan baffle nut and an additional nut is used to secure the bracket, low oil pressure may result.
If the oil pump pick up screen is installed over a stud nut it will tilt the pickup screen mounting flange just enough to allow air leakage. Air entering the oil supply tube will cause low and/or erratic oil pressure.
The torque values to use while installing the baffle and pick up screen are listed at top left.
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