1/1/2003
Connecting rod bolt torque specifications used in various Allis Chalmers agricultural or industrial engines
Engine Builders: In an effort to clarify the confusion about connecting rod bolt torque specifications used in various Allis Chalmers agricultural or industrial engines, the AERA Technical Committee offers the following information. This information applies to both early and late style engines, as several different hardware combinations have been used in the 201, 301 and 426 c.i.d. engines.
Two different connecting rod and cap mating surface finishes were used and identification can be made by visual inspection. Early style connecting rods have a serrated mating surface between the cap and the rod. Middle and late style connecting rods can be identified by a flat parting line between the cap and the rod.
All Models
To assemble, use a light amount of engine oil on capscrew threads and on the underside of the capscrew head. Tighten cap screw using a minimum of two incremental torque steps or three steps on higher torque hardware (7.0L). Non-serrated connecting rod caps MUST be aligned with the rod during installation. To do so, install hardware finger tight, use two feeler gauges between the rod/cap assembly and the side of journal to hold assembly snug to one side of journal. Tighten hardware in multiple steps and then remove feeler gauges.
2000 series, 3.3L and 4.9L series engines
(2200, 2800, 2900, 433 & 649 types, etc.)
Early-style rods use hex-head capscrews with washers and the rod cap bolt holes have a 30° chamfer. Capscrews are .375˝ – 24 x 2.00˝ long, Grade 8. Tighten these capscrews to 50 ft.lbs.
Later-style rods have the rod cap chamfer deleted and use a new 12-point capscrew. Capscrews used are .375˝ - 24 x 2.00˝ long, Grade 100. Tighten these capscrews to 45 ft.lbs.
Note: Do not use later 12-point capscrews in early rods with chamfered holes or loosening of capscrews will occur. Early rods may be machined to remove the chamfer and balanced to accept later capscrews.
3000 Series, 7.0L series (3400, 3500, 3700, 3750 & 670 types, etc.)
Early-style rods use serrated rod caps with hexhead capscrews and washers. Capscrews are .437˝ – 20 x 2.25˝ Grade 8. Tighten these capscrews to 85 ft.lbs.
Middle-style rods use smooth machined rod and cap mating surfaces. Socket head capscrews are .437˝ – 20 x 2.156˝ long, Grade 100. Tighten these capscrews to 70 ft.lbs.
Later-style rods use smooth machined rod and cap mating surfaces. 12-point capscrews are .437˝ – 20 x 2.156˝ long, Grade 100. Tighten these capscrews to 70 ft.lbs.
Note: Do not use middle- or later-type hardware in early serrated connecting rods.
Engine Builders: The AERA Technical Committee offers the following information on cylinder head cracks on John Deere 10.5L and 12.5L diesel engines. These cracks are located in the bridge area of the cylinder head and are caused by thermal-mechanical stress.
The cylinder heads may show signs of cracking in the bridge area between the intake valve seat and/or exhaust valve seat. It is not uncommon for these cylinder heads to experience this cracking condition.
If the crack is visible but does not go beyond the valve seat then the cylinder head is reusable. If the crack extends beyond the valve seat insert, the cylinder head should be replaced, according to John Deere.