PIN 4N3808 - Caterpillar

Table 1
Required Tools
Tool Part Number Part Description Qty
A - Compression Test Tool Gp 1 The following conditions can affect the results of the cylinder compression test:
Battery
Condition of the starter
Ambient conditions
Quality of the compression gauge
Illustration 1 g03797781
Typical example
Remove the glow plug (1) from the cylinder in order to measure the compression for that cylinder. Refer to Disassembly and Assembly, "Glow Plugs - Remove and Install" for the correct procedure.
Illustration 2 g00564993
Checking compression of engine
Connect a compression gauge to the cylinder.
Operate the starter and record the pressure on the compression gauge.
Be sure to measure the compression on all of the cylinders. If all of the cylinders are not checked an improper diagnosis may result. The compression pressure will vary with the change in engine rpm. It is necessary to keep the engine rpm constant for all cylinders when you are taking a compression reading.
Repeat for each cylinder. Note: Compression tests should only be used to compare pressures between cylinders of an engine. If one or more cylinders vary more than 350 kPa (51 psi) then those cylinders may be damaged.Note: The cylinder compression test should not be the only test for determining the condition of an engine.
Table 2
Standard at Assembly Repair Limit
Compression Pressure(1) 2940 kPa (426 psi) 2450 kPa (355 psi)
(1) The compression pressure is taken at 250 rpm.
Repair procedures must be taken if the compression is lower than the repair limit.