Cast iron housings and cylinder blocks can have small holes because of damage during operation or pitting that is caused by cooling system maintenance that is not correct. Repair of these small holes can some times be made with the use of pipe plugs. The maximum plug diameter is limited to 1.5 times the wall thickness of the casting to be repaired and the center to center distance between plugs must be a minimum of 152 mm (6.0″).
This repair procedure must be used for low pressure systems only, such as cooling system pressure in engine blocks. Do not use the pipe plugs to make repairs on castings that are used in systems with pressures above 170 kPa (25 psi).
To start, put a mark on the area in which the plug will be used. Use a center punch to make a small hole in the castings to start the drill. Drill and tap the hole to the correct size for the pipe plug to be used. Put 6V1541 Quick Cure Primer on both the threads of the pipe plug and the tapped hole. Put 9S3265 Retaining Compound on the threads of the pipe plug. Install the pipe plug and tighten it to the correct torque. See Illustration 1.
The pipe plug must be long enough to be above the front and back surfaces of the casting wall to make sure of the correct thread engagement. Grind the top of the pipe plug even with the casting surface. See Illustration 2. Put paint on the ground surface.
Caterpillar recommends to use the procedure that follows to clean the oil passages in all new, used and reconditioned crankshafts and cylinder blocks.
1. Use steam cleaning or a similar method to remove as much external dirt, oil or preservative coating as possible.
2. Remove all covers and plugs from the oil passages. See Guideline For Reusable Parts, Visual Inspection Of Crankshafts, Form SEBF8043 for information about crankshaft plug removal.
3. Position cylinder blocks upside down (oil pan rails up).
4. Use a petroleum base cleaning solvent and the correct size brush in a variable speed drill to loosen debris or carbon deposits (sludge) in all crankshaft or cylinder block oil passages. Operate the drill at approximately 300 rpm. The diameter of the brush must be slightly larger than the diameter of the oil passage that is to be cleaned. Make sure the end of the brush goes to the end of each oil passage. Each oil passage must be cleaned vigorously and repeatedly from every possible direction.
5. After most of the debris has been removed using the brush and petroleum base cleaning solvent, use the brush and a solution of detergent and water to clean out all visible debris.
6. After brushing, use the aerated nozzle (“Jiffy Gun”) and hot alkaline type cleaning solution to clean and flush all debris from the oil passages.
7. Flush auxiliary passages toward the main oil gallery, then flush the main gallery from one end. Flush all main galleries such as the camshaft bores in a similar manner. Always flush out the main galleries last, to wash away debris flushed from the auxiliary passages.
8. One major source of debris that is not obvious is small metal particles that are created when pipe plugs and other plugs are installed. The following procedure will reduce the dangers from this source.
a. Clean the cylinder block or crankshaft first with all plugs removed.
b. Use a small brush to clean the threads of each plug and tapped hole; use detergent and water. If threads are damaged or have burrs, use a tap to clean and repair them. Then clean the threads and passages again with a brush and use the aerated nozzle (“Jiffy Gun”) to flush the passages.
c. Install all plugs in the crankshaft and cylinder block. Be sure the correct plugs are used. Tighten each plug to its correct torque. See the appropriate Service Manual module.
d. Repeat flushing of the main galleries (after the plugs are installed) with the aerated nozzle and cleaning solution to remove particles caused by installation of the plugs. (Although auxiliary passages can only be flushed from one end, this operation will usually be adequate and better than not flushing after the installation of the plugs).
9. Use clean water under pressure to flush the rest of the detergent and water solution out of the oil passages. Then use air pressure to dry the cylinder block or crankshaft. (Do not allow surfaces to dry by evaporation. Corrosion and rust are more likely).
10. If the crankshaft or cylinder block is not to be used immediately, flush the oil passages with clean oil and put plastic plugs in all oil passage openings. Put a rust inhibitor over the complete cylinder block or crankshaft. Put the crankshaft or cylinder block in VCI (volatile corrosion inhibitor) storage bags for long term storage (more than 30 days). For more information about rust inhibitor materials, contact the local Caterpillar Dealer.
11. Before a crankshaft or cylinder block (that is new or has been in storage) is put into service, be sure to remove all plastic plugs and rust inhibitor. Flush out the oil passages. Then dry and lubricate as necessary before installation.
It is very important for an engine to have adequate (needed) lubrication during the first seconds of operation. A “dry start” (without needed lubrication) of an engine can cause bearing damage. An engine generally has enough oil on the parts for lubrication during engine start-up; however, this lubrication may not be enough or may be lost if the engine has been in storage for any length of time. To prevent the possibility of a “dry start” and bearing damage during the first seconds of operation, pressure lubrication of the engine is necessary (fill the main oil passages with oil under pressure).
Special Instruction, Form SMHS7701, gives the pressure lubrication procedure for engines.
It is essential to bearing performance that the lubrication system be maintained properly. This maintenance will help keep the oil clean and free of contamination. Correct maintenance includes …
- … using oil of the correct grade and viscosity
- … maintaining the correct oil level
- … adhering to the recommended oil and filter change intervals
- … using the correct oil filter; one known to be high quality
The appropriate Operation and Maintenance or Lubrication and Maintenance Guide will give recommendations for oil grade, viscosity and change intervals. Use of the correct Caterpillar filter is the best way to make sure filter performance is satisfactory.
Cleanliness is a major factor in preventing bearing failures. Do not assemble debris into the engine. Successful overhauls demand clean work areas and clean components for assembly. It is important that the correct procedures and tools are used to achieve the desired cleanliness.
Cleanliness must start with the disassembly of the engine. First, use a steam cleaner or similar equipment to clean the external surface of the engine. This will help keep the assembly area clean and reduce the chance of contamination in an assembled engine. Use plastic plugs and covers to prevent debris from entering the disassembled engine components. Use the correct tools, lifting devices and storage racks to avoid damage and protect the engine components.
One reason for bearing failure after an engine overhaul is debris that was not removed from the oil passages in the crankshaft and cylinder block. Some of this debris (carbon deposits or sludge) is a product of fuel combustion that, over a long period of time, mixes with oil and becomes thick.
Another source of debris is metal chips or abrasive material that is not removed after an engine or bearing failure or after a reconditioning operation. This debris can cause damage to the bearing journals and bearings when the engine is first started.
Extra care must be taken after a bearing failure to make sure all the debris and bearing material is removed from the entire engine lubrication system. The crankshaft oil passages must be cleaned. All plugs, orifice dowels, cooling jets and hoses must be removed from the block so the oil passages can be cleaned. Remove auxiliary equipment that is lubricated by the engine oil. Disassemble this eqiupment and clean the oil passages.
It is important that all debris is removed from the oil passages in the crankshaft and cylinder block. Cleaning must be complete and thorough, because cleaning that is not thorough may only result in loosening debris, allowing it to break free and damage bearings and other components after the engine is put into service.
Oil passages must be thoroughly cleaned with brushes to make sure all carbon deposits (sludge) and debris are removed. Good quality brushes are required. The following brushes are available from Caterpillar and are in sizes that will clean all current engine blocks and crankshafts.
NOTE: When the main oil passage in the cylinder block is cleaned, it will be necessary to weld a 3.18 mm (.125″) mild steel rod to the end of the brush handle. Make sure the rod is long enough to let the brush go all the way through the cylinder block. See Illustration 1.
Most of the time debris can not be removed completely when only a high pressure wash or a high pressure nozzle is used to clean the oil passages. A nozzle with a high aerated flow or pulsating flow is recommended. One aerated nozzle that can be used is the “Jumbo Jiffy Gun” with “Air Boost.” Parts for this tool are shown in the chart that follows.
Use a 2 to 3% (by volume) alkaline type cleaning solution (detergent) with the cleaning gun (aerated nozzle). The temperature of the cleaning solution must be 43 to 55°C (110 to 150°F).
Special Instructions will be available to give more detailed information about the cleaning equipment and procedures.
All 3400 Series Engines
Petroleum products can damage the rubber used in spacer plate water seals (4W1055 Seal). This damage can be caused by the use of a water soluble oil in the cooling system or by contamination during maintenance or assembly.
When petroleum products come into contact with these seals they cause the rubber to swell. This can result in extruding and eroding of the inside diameter of the seal lip.
All Caterpillar-built Engines, Except 1100 and 3100 Series Engines and 3208 Engines
The 5P8665 Cylinder Liner Puller is available to remove cylinder liners from all Caterpillar Engines that use cylinder liners. This new tool is easy to install and remove. An impact wrench with a .50″ (12.7 mm) drive will have enough force to remove the liners. Generally, less than 10 seconds is needed to remove each liner.
The arm assemblies on the puller are adjusted to fit the length of the liner to be removed. They are then pushed together and installed into the cylinder liner. The spring loaded arms are then moved out so the feet on the ends of the arm assemblies are under the bottom of the liner. The bolt is turned clockwise to remove the liner.
The 5P8665 Cylinder Liner Puller can remove cylinder liners with dimensions up to 7.00″ (177.8 mm) in diameter and 18.00″ (457.2 mm) in length.
The separate parts of the 5P8665 Cylinder Liner Puller are available to make repairs if necessary (see the Illustration).
During the installation of a new cylinder block as a replacement for a damaged block, many dealers have desired a recommendation on the installation of new main bearings. This can be a problem when the bearings in the former cylinder block are in good condition and are not badly worn.
In the past, for some specific conditions, the recommendation has been given to install the used bearings, but this recommendation will no longer be made. Tests and inspections made during a period of time show that the installation in a new cylinder block of bearings that have been used in a different block can cause problems and is not generally practical.
When a cylinder block is machined at the factory, necessary tolerances cause small differences between cylinder blocks. These differences can change several factors that have an effect on bearing wear, including stress points, wear areas, clearances, bearing crush and possibly taper in the bearing bores. Because of these wear factors, bearings which have been used in one cylinder block can have a shorter service life when installed in a different cylinder block.
For this reason, the recommendation is to install new main bearings during installation of a replacement cylinder block. The use of new bearings in a new block is the best procedure to be sure the bearings will give maximum service life.
All Engines In All Applications
The Service Manuals and other Caterpillar literature give the procedure to check the clearance between the main bearing journals and main bearings with the crankshaft installed in the engine. In some Service Manuals, part of this procedure is to “Rotate crankshaft one complete revolution with lead wire installed.” This instruction is wrong. An accurate check of main bearing clearances can not be made if the crankshaft is rotated (or even moved).
Also, most Service Manuals do not tell you to lift up the crankshaft when the engine is in the normal operating position. Unless the crankshaft is lifted, the lead wire will be made too flat by the weight of the crankshaft and cannot give you a correct measurement of main bearing clearance.
The procedure will be changed when revisions are made to the Service Manuals. This note will be used:
NOTE: When the bearing clearance is checked and the engine is in its normal operating position, such as in the vehicle, the crankshaft will have to be lifted up with a force equal to the weight of the crankshaft and held against the upper halves of the main bearings to get a correct measurement with the wire. The wire will not hold the weight of the crankshaft and give a correct indication. If the engine is in position on its side, such as on an engine stand, it is not necessary to hold the crankshaft up. Do not turn crankshaft when lead wire is in position to check clearance. If lead wire is not available, PLASTIGAGE can be used to check bearing clearance.
Write a note in the Service Manual engine modules in the disassembly and assembly sections under crankshaft that makes reference to this Engine News.
Publication Date -30/08/1978
All Caterpillar Engines
There have been some reports about marks on engine bearings in parts shipments. These marks are caused by tools that are used to measure bearing thickness. They do not affect bearing performance or service life in any way.
There are three basic quality control marks found on some bearings. The most common type of mark is two parallel lines near the edges of the bearing, as shown in Illustration 1. Illustration 2 shows another type of mark. There are usually five or six of these marks evenly spaced on the back of the bearing. The third type of quality control mark is shown in Illustration 3. These are short marks which extend in from both edges on the front of the bearing.