John Deere約翰迪爾強鹿發(fā)動機氣門行程的測量方法與技巧

NOTE: Measuring valve lift provides an indication of wear

on camshaft lobes and camshaft followers or pushrods

.

1. Remove rocker arm cover.

2. Set No. 1 piston at TDC compression stroke and installJDG1571 or JDE81-4 Timing Pin in flywheel.

3. Set rocker arm-to-valve tip clearance to 0.00 mm (0.00in.) for:

· No. 1 and 3 exhaust and No. 1 and 2 intake valveson 4-cylinder engines.

· No. 1, 3, and 5 exhaust and No. 1, 2, and 4 intakevalves on 6-cylinder engines.

4. Place dial indicator tip on top of valve spring cap(retainer) or rotator. Preload indicator tip and set dial at0.0 mm (0.0 in.).

5. Remove timing pin from flywheel and manually rotateengine one full revolution (360°) in running directionusing appropriate flywheel turning tool.

6. Observe dial indicator reading as valve is moved to fullopen. Record maximum reading and compare withspecifications given below.

Specification

Intake Valves—Lift 11.77—12.21 mm(0.463—0.481 in.)

Wear Limit ................................................................ 11.34 mm (0.447 in.)

Exhaust Valves—Lift 11.51—11.94 mm(0.453—0.470 in.)

Wear Limit ................................................................ 11.08 mm (0.436 in.)

7. Follow same procedure for all remaining valves andrecord readings.

A—Front of Engine

B—No. 1 Piston TDC Compression

C—No. 4 Piston or No. 6 Piston TDCCompression

E—Exhaust Valve

I—Intake Valve

If valve lift on all valves is within specifications, adjustvalve lash to specified clearance. (See CHECK ANDADJUST VALVE CLEARANCE earlier in this group.)If valve lift on one or more valves is not withinspecification, remove and inspect entire valve train andcamshaft.

8. Rotate engine one full revolution (360°). Lock engineat:

· TDC No. 4 compression stroke for 4-cylinderengines.

· TDC No. 6 compression stroke for 6-cylinderengines.

9. Set rocker arm-to-valve tip clearance to 0.0 mm (0.0in.) for:

· No. 2 and 4 exhaust and No. 3 and 4 intake valveson 4-cylinder engines.

· No. 2, 4, and 6 exhaust and No. 3, 5, and 6 intakevalves on 6-cylinder engines.

10. Repeat steps 4—7.