3408 and 3412 Long Blocks Caterpillar

3408 and 3412 Long Blocks

Long Block Selection: General Information
 
The purpose of this technical supplement is to help you decide if there is a Caterpillar remanufactured long block available for a particular engine application. When making your decision, please keep the following points in mind.

Long blocks are not available for every engine application. The long blocks we do offer can, however, be used to service many applications even though the long block does not exactly match the original engine configuration. When the consist of the Reman product offering differs from the consist of a customer's engine, only the dealer and customer can decide whether or not it makes economic sense to change the parts that differ.

It's Caterpillar's policy to incorporate the latest critical engineering changes into Cat Reman products. Therefore, long blocks may be offered with some parts from a later design era as service repairs for engines from an earlier design era. An example is the 3406C crankshaft, connecting rods, and pistons which are not in certain 3406B long blocks. The result is that the parts in the long blocks match each other but do not match the parts consist of new production engines, nor do they match any single parts book. When long block parts consists differ from the official parts list, Reman provides an engine plate alerting the customer to Special Instruction or Service Magazine articles for information on non-standard parts.

Make sure any future engine/long block repairs, which do not use parts called for by the original parts book, or official replacements called for by parts and service sources, are carefully documented. If you choose to make any configuration or consist changes, good documentation can prevent problems the next time parts are ordered.

3408 and 3412 Long Block General Information

The 3408 and 3412 long blocks are shipped with the front cluster gears in place to maintain the timing between the camshaft and pistons to prevent damage to pistons and/or valves if the long block is rotated from its shipping location of "top dead center, number one firing." (The camshaft drive gear on these engines is not for use in engine arrangements with camshaft-driven fans.) Please reference the following Service Magazine articles for additional information:

    "Fan Now Driven By Crankshaft", May 23, 1983.

    "Fan Driven Conversion Group Available To Change Fans From Gear Driven to Belt Driven", October 17, 1983.

    "Fan Now Driven By Crankshaft", March 8, 1985.

The 3408 long blocks incorporate the thick web/thick cheek crankshaft design found in 3408B series engines. When used together, the new style block, crank and cam will directly replace the previous style components. Some flywheel housing machining may be required to accommodate the thick cheek crankshaft (see: Service Magazine 14, December '87 and Service Magazine 13, May '85). Since these "new style" long blocks are intended to service all 3408 engines, either style core will be accepted for full core credit.

The 3412 long blocks include the latest design (quieter-running, increased strength, straight-toothed) front gear group. Engines with the previous style helical front gear group will need the oil pump drive gear replaced with the new style gear (2W3875). The effective serial numbers for the change to the new style straight toothed valve gear group are as follows: 38S16935-Up, 60M05364-Up, 81Z1572-Up, 7DB00899-Up, 9XF00076-Up, 7315311-Up.

3408 and 3412 Direct Injection (DI) long blocks incorporate the latest wide taper connecting rods and thick top ring pistons. As of this writing, these improved parts can be be used in combination with each other, to service all 3408 DI and 3412 DI engines back to first production. Any future repairs must be made with parts, which are compatible with the long block. Please review the following Engine News articles for more information:

    "Connecting Rod Changes and Replacement Information", March 12, 1980.

    "Reference List of Pistons Used with the Different Types of Connecting Rods", September 10, 1980.

    "New Piston Group has a Thicker Top Ring", December 15, 1982.

Don't forget to use NPR or other sources to find the most current part numbers that replace the ones shown in these old articles.

3408 and 3412 Reman long blocks are shipped with temporary valve mechanism covers and a valley cover plate (117-5974) to guard against damage and debris during shipment. Lifting eyes are also provided to assist the dealer in removing the block from its packaging. The valley cover plate, the valve mechanism covers and the lifting eyes are to be returned with the core. The valve mechanism covers and lifting eyes from the core engine should be kept for use on the new replacement Reman long block. Information tags are attached to 3408 and 3412 long blocks to remind the mechanic which parts to return.

Long Block Selection: General Information

First, decide whether the customer's engine is a 3408 or 3412 and determine whether it has pre-combustion chambers (PC) or direct injection (DI). Normal parts and service sources can be used to look up this information by engine serial number, if necessary. This will narrow down the list of long block candidates shown on the following chart.

If the customer's engine is a "DI", you will have to wait until the next step to further narrow the candidate's list. Next, use normal parts sources (parts book, microfiche, SIS, etc.) to look up the current piston part number for the customer's engine. If the customer's piston is not one of the numbers shown under "Piston P/N's...", use NPR or other sources to find the most current part number intended to service the customer's engine.

If the customer's piston still doesn't appear in the chart, Reman does not offer a perfect service replacement long block. If you are willing to do further research, you may find a Reman long block which can be used as a service repair. The following articles may help with your research.

    "Connecting Rod Changes and Replacement Information" Engine News, March 12, 1980.

    "Reference List of Pistons Used with the Different Types of Connecting Rods" Engine News, September 10, 1980.

    "New Piston Group has a Thicker Top Ring" Engine News, December 15, 1982.

Don't forget to use NPR or other sources to find the most current part numbers that replace the ones shown in these old articles.

If the customer's piston or an acceptable service repair piston is shown, you should now have narrowed the candidates down to one or two columns of the chart. Next, follow the remaining candidate columns down into the consist section of the chart. Check the camshaft, then cylinder head part numbers shown against the part numbers called for (by normal parts sources) to service the customer's engine. By this point, you have narrowed the search down to one candidate long block part number. Now check the other part numbers listed in the same column of the consist chart. For a long block candidate to become a selection, all the part numbers listed under the long block part number should match the correct service part numbers for the customer's engine. You may select a long block which isn't a perfect match if you believe changing the parts which don't match is worth the time and money to do the work. Remember, 3408 long blocks have a thick cheek crankshaft intended to service all 3408's.

NOTE: Read the notes referenced in the chart. These notes explain, among other things, important adaptability and shipping information.
 

NOTE A- This number is for reference only. The Reman consist does not exactly match any production part.
NOTE B- Crankshaft is positioned at top dead center, number one firing, before shipment.
NOTE D- Core Plugs in rear face of Cylinder Heads may not match the customer's application. Form SEHS9776 is attached to rear of Cylinder Head.
NOTE E- The Lifting Group is for handling during installation and removal from shipping container. The customer may have to use the Lifting Eyes from the removed engine. Form SEHS9666 is attached to the Rear Eye.
NOTE F- This Valve Cover Group is for debris protection. The customer will have to use the Valve Cover Lids from the removed engine. Form SEHS9665 is attached to the Front Valve Cover Lid.
NOTE G- With 40 mm Injector Nozzle Adapters for use with later, long, thin, "PENCIL" style Fuel Injector Nozzles (Ref. Nozzle P/N's: 4W7018, 4W7019, and 4W7020). The Injector Nozzles are not included with the Long Block.
NOTE H- With 55 mm Injector Nozzle Adapters for use with short, fat, "CAPSULE" style Fuel Injectors (Ref. Nozzle P/Ns: 4W7012, 4W7013, 4W7014). For more information see: "New Cylinder Heads and Fuel Nozzle Adapters Used", Engine News, July 1985 (and Supplement:4/00/86). The Injector Nozzles are not included with the Long Block.
NOTE J- "Thick/Cheek Web" Crankshaft. This crankshaft, together with the later Cylinder Block, is intended to service early style engines. Do not reject this long block as a candidate just because the Crank and Block part numbers do not match the customer's engine. The parts in the Long Block match each other. Older Style Flywheel Housings will have to be machined to provide clearance for the thick cheek crankshaft. (see: Service Magazine 14 December '87 "Earlier Flywheel Housings Can be Modified for Use with Later Crankshafts" and Service Magazine 13 May '85 "New Crankshaft, Cylinder Block and Camshaft Used"). Heavy duty Rear Gear Group Applications will require exchanging the Rear Gear Group and/or Balancer.
* Use of 0R4278 Long Block for 988F Wheel Loaders having engine serial numbers before 48W40078 requires conversion of Front Gear Train to a helical design. Effective with engine serial number 48W40078, the Front Gear Train contains Helical Gears, and 0R4278 Long Block can be used by transferring components from the production engine, including the 4P3581 Rear Gear Group.