CLIP 3E4071 - Caterpillar

Table 1
Tools Needed
Part Number Part Name Quantity
348-5430 Multi-Tool Gp 1
285-0901 Blowby Tool Group 1
NETG5044 Software license 1 Table 2 lists typical ranges of crankcase blowby for engines with a low number of service hours. The ranges are approximate. Use the values for reference.
Table 2
Approximate Ranges of Crankcase Blowby for New G3400 and CG137 Engines
Engine Liters Per Minute Cubic Feet Per Minute
G3406 189 to 212 6.7 to 7.5
G3408 and CG137-8 212 to 288 7.5 to 8.3
G3412 and CG137-12 307 to 354 10.8 to 12.5 Measure the crankcase blowby of an engine after approximately 250 hours of operation. Record the data as a benchmark. Continue to measure the blowby periodically. Comparing the recorded data to the new data provides information about the condition of the engine.Note: Crankcase blowby is one of the three factors that help to determine the major overhaul interval. For more information, refer to the Operation and Maintenance Manual for your engine.After a new engine is used for a short time, the blowby can decrease as the piston rings are seated. For an engine that remains in good repair, the blowby will gradually increase as the piston rings and cylinder liners show wear. More fumes are exhausted through the crankcase breather. The crankcase breather will become clogged more rapidly. Excessive crankcase pressure can also cause oil leakage at the gaskets and the seals.The blowby of a worn engine may exceed the blowby of a new engine by two times or more.Note: A problem with the piston rings causes the oil to deteriorate rapidly. Information regarding the condition of the piston rings can be obtained from the measurement of the blowby and the results of oil analysis.A sudden increase in blowby could indicate a broken piston ring. This condition will cause the engine to run rough. The following conditions are other potential sources of blowby:
Worn valve guides
A turbocharger seal that leaksA rebuilt engine can have a high blowby due to the following factors:
The piston rings are not seated properly.
Worn parts such as valve guides were not replaced.By keeping a record of the results, a gradual increase in the amount of the blowby will be noted until the amount has become excessive.The 348-5430 Multi-Tool Gp with the 285-0901 Blowby Tool Gp is used to check the amount of blowby.