Technical Sample One




This manual is written for an experienced technician. Essential tools required in performing certain service work are identified in this manual and are recommended for use.

Live with safety: Read the safety messages in the introduction of this manual and the cautions presented throughout the text of the manual.


This is the safety-alert symbol. When you see this symbol on the machine or in this manual, be alert to the potential for personal injury.

Use this component technical manual in conjunction with the machine technical manual. An application listing in the introduction identifies product-model/component type-model relationship. See the machine technical manual for information on component removal and installation, and gaining access to the components.

This manual is divided in two parts: repair and operation and tests. Repair sections contain necessary instructions to repair the component. Operation and tests sections help you identify the majority of routine failures quickly.

Information is organized in groups for the various components requiring service instruction. At the beginning of each group are summary listings of all applicable essential tools, service equipment and tools, other materials needed to do the job, service parts kits, specifications, wear tolerances, and torque values.

Component Technical Manuals are concise service guides for specific components. Component technical manuals are written as stand-alone manuals covering multiple machine applications.

Fundamental service information is available from other sources covering basic theory of operation, fundamentals of troubleshooting, general maintenance, and basic type of failures and their causes.



Too little valve clearance throws valves out of time. Valves open too early and close too late. This causes the valves to overheat due to hot combustion gases rushing past valves when out of time. Overheating lengthens valve stems which prevents proper seating of valves. The valves seat so briefly or poorly that normal heat transfer into the cooling system does not have time to take place, causing burned valves and low power.


Too much valve clearance causes a lag in valve timing causing engine valve train imbalance. The fuel-air mixture enters the cylinders late during intake stroke. The exhaust valve closes early and prevents waste gases from being completely removed from cylinders. Also, the valves close with a great deal of impact, which may crack or break the valves and scuff the camshaft and followers.


NOTE: Valve clearance should be checked with engine cold.


1. Remove rocker arm cover and ventilator hose (A). 2. Remove plastic plugs (B).

1. 卸开摇臂杆盖和通风管(A)。
2. 取下塑料插塞(B)。

IMPORTANT: Visually inspect contact surfaces of valve tips or wear caps and rocker arm wear pads. Check all parts for excessive wear, breakage, or cracks. Replace parts that show visible damage


3. Rotate engine with the JDE81-1 or JDG820 Flywheel Turning Tool (A) until JDE81-4 Timing Pin (B) engages timing hole in flywheel.

3. 利用JDE81-1或JDG820飞轮转动工具(A)转动引擎,直到JDE81-4定时针(B)与飞轮中的定时孔啮合。

If the rocker arms for No. 1 cylinder are loose, the engine is at No. 1 “TDC-Compression.” If the rocker arms for No. 6 cylinder are loose, the engine is at No. 6 “TDC-Compression.” Rotate the engine one full revolution to No. 1 “TDC-Compression.”


4. With engine lock-pinned at “TDC” of No. 1 piston’s compression stroke, check and adjust (as needed) valve clearance on Nos. 1, 3 and 5 exhaust valves and Nos. 1, 2 and 4 intake valves.

4. 使引擎销锁在1号活塞压缩冲程的“TDC”位置,检查并视需要调节1、3、5排气阀和1、2、4进气阀的气门间隙。

Intake Valves . . . . . . . . . . . . . . . . 0.331-0.431 mm (0.013-0.017 in.)
Exhaust Valves . . . . . . . . . . . . . . . 0.457-0.559 mm (0.018-0.022 in.)

进气阀. . . . . . . . . . . . . . . 0.331-0.431毫米(0.013-0.017英寸。)
排气阀. . . . . . . . . . . . . . .457-0.559毫米(.018-0.022英寸。)

5. If valve clearance needs to be adjusted, loosen the locknut on rocker arm adjusting screw. Turn adjusting screw until feeler gauge slips with a slight drag. Hold the adjusting screw from turning with screwdriver and tighten locknut to 27 N·m (20 lb-ft). Recheck clearance again after tightening locknut. Readjust clearance as necessary.

5. 如果气门间隙需要调节,松开摇臂调节螺丝上的防松螺母,转动调节螺丝直到测隙规滑动时稍带阻力为止。用螺丝刀止住调节螺丝不让其移动,并将防松螺母拧紧至27牛顿·米(20磅-英尺)。拧紧防松螺母后,再一次检查间隙,视需要重新调节间隙。

6. Rotate flywheel 360° until No. 6 piston is at “TDC” of its compression stroke. Rocker arms for No. 6 piston should be loose.

6. 转动飞轮360o,直至6号活塞处于其压缩冲程的“TDC”位置。6号活塞的摇臂杆应该是松的。

7. Check and adjust (as needed) valve clearance to the same specifications on Nos. 2, 4 and 6 exhaust and Nos. 3, 5, and 6 intake valves. Tighten valve adjusting screw locknut to 27 N·m (20 lb-ft).

7. 检查并视需要将气门间隙调节到与2、4、6号排气阀以及3、5、6号进气阀相同的规格。将气门调节螺丝防松螺母拧紧至27牛顿·米(20磅-英尺)。

8. Recheck clearance on all valves again after locknut is tightened.

8. 防松螺母拧紧后,再对所有气门的间隙重新检查一次。