0388140 JOHNSON COVER, Air silencer

Table 1
Revision Summary of Changes
01 Added effectivity. Introduction
Do not perform any procedure in this Special Instruction until you have read and understood the information.Using these instructions can help detect a single cylinder with excessive pressure blowing past the piston rings.The blowby can be due to piston rings that are worn or broken. The blowby can also be due to worn or damaged cylinder liners.The common materials that are needed for the testing can be obtained in most shops.This test uses the crankcase breathers or T-hoses, where all venting locations are fitted with caps or plugs.One plug is drilled to provide restriction and amplification of the pressure signal.One is fitted with a 1/8 inch hose barb fitting and a hose that is routed to a manometer.All other breathers are capped off.A manometer is used with the cylinder cutout function of Caterpillar Electronic Technician (ET) to determine crankcase pressure changes associated with individual cylinders.A torque converter load is maintained on the engine during the test to maintain a small load on the engine. The load enables all the injectors to have similar injection duration so that failed cylinder can be found more easily.Ensure that there are no other leak paths for exhaust gas to escape the crankcase to perform the test.Note: Oil filter differential pressure typically runs between 2 and 4 PSI at coolant temperatures above 77° C (170° F). Excessive blowby is suspected If oil filter differential pressure alarms are present or the filter differential pressure exceeds 5 PS.
Do not operate or work on this machine unless you have read and understand the instructions and warnings in the Operation and Maintenance Manual. Failure to follow the instructions or heed the warnings could result in injury or death. Contact your Caterpillar dealer for replacement manuals. Proper care is your responsibility.
Required Tools
Table 2
QTY Part Number Description
1 448-0722 Probe
1 448-0723 Probe
1 448-0724 Tool Gp
1 448-0725 Tool Gp Required Test Materials
Illustration 1 g03251500
(1) 1/8 inch hose
(2) Hose clamp
(3) 1/8 inch hose barb fitting in a plug or cap
(4) Plug or cap with drilled hole for restriction and amplification
(5) Manometer
Table 3
Required Materials
Material Comment
3 ABS plastic plugs 1-1/2 inch inner diameter and 2-1/4 inch outer diameter
Or
Six similar caps The plugs or caps are used to seal off the breathers.
Install a threaded fitting into one plug or cap, enabling installation of a 1/8 inch hose barb fitting (3).
Drill a 1/2 inch hole into one plug or cap (4). A 1/2 inch hole is a good starting place.
Having a few different caps with 3/8, 1/2, and 3/4 inch orifices will allow the restriction to be varied as necessary. Different sizes can help produce 4 to 10 inches H2O at the beginning of the test.
The holes in the plugs or caps provide restriction and amplify the signal to the manometer. A smaller hole increases the restriction (pressure) and therefore increases the amplification. Too little or too much amplification will make cylinders with more blowby difficult to find.
A variable sized orifice can be fabricated by inserting a ball valve into the hole. The ball valve can be set to the desired restriction and resulting amplification at the beginning of the test. Do not alter the valve throughout the duration of the testing.
Having different sizes that can reduce the amplification can be helpful with engines that have higher blowby.
3 to 6 hose clamps Clamps (2) secure the plugs or caps onto the breathers.
1/8 inch rubber hose long enough to route from the engine to the engine control. Use hose that resists kinks. Hose (1) will convey pressure changes to the manometer.
Digital manometer with a resolution of 0.01 inches H2O Manometer (5) will measure pressure changes.
Personal computer with Caterpillar Electronic Technician (ET) software Cat ET will be used to perform the cylinder cutout test. Install the Test Materials
Illustration 2 g03251555
(1) Plug with the orifice hole
Illustration 3 g03251519
Alternative locations for the plugs
(2) Outlet of the breather
(3) Outlet of the tee
Install the plug or cap with the 1/2 inch orifice (1) into the outlet of one of the crankcase breathers (2). The preferred location is nearer to the engine control. Alternatively, install the plug or cap into the tee hose (3) for a pair of breathers.The plug provides restriction and amplifies the signal to the manometer.
Illustration 4 g03251546
(4) Plug with fitting for the 1/8 inch hose
Install the plug or cap with the 1/8 inch hose barb fitting (4) into another breather or tee hose. The preferred location is