Cylinder Head Bolt - Revised Surface
Category Applicable Model/s Subject Bulletin No. 014/851 626 DIESEL CYLINDER HEAD BOLT Issued 8/30/85
Revised
DESCRIPTION
The cylinder head bolt surface is specially treated to lower the coefficient of friction. Because of this treatment, a higher clamping force can be obtained with a lower tightening torque.
In some cases, bolts may have an excessive amount of the surface treatment agent. This may be especially true when using a new bolt (with white surface treatment) when reinstalling a cylinder head. As a result, a bolt may later loosen.
CYLINDER HEAD BOLT:
For this reason, the surface treatment of the bolt has been changed since the production date of March 1, 1985. The new bolt can be distinguished from the old by its treatment color as shown below.
VIN OF PRODUCTION CHANGE
626 Diesel: JM1GC222 F1601231 March 1, 1985
PARTS INFORMATION
PART NUMBER
DESCRIPTION INTERCHANGEABILITY
NEW OLD
RF01 10 135A RF01 10 135 Cylinder Head Bolt NEW --> OLD + M
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CAUTION:
When you replace the cylinder head bolt, always check if the replacement bolt is the new style (black surface treatment) or the old style (white surface treatment). If the old style cylinder head bolt is used for the replacement, be sure to rub off the white surface treatment agent. Please refer to the following installation procedure for more detailed information.
Old Bolt (RF01 10 135):
INSTALLATION PROCEDURE
Old Bolt (RF01 10 135)
1. Rub off the surface treatment agent (white agent) on the seat of the head and the thread portion of the bolts using a wire brush. Make sure that more than 80% of the agent is removed.
2. Apply engine oil to the seat of the head and the thread portion of the bolts.
Install the Bolts:
3. Install the bolts and tighten them to specification in the order shown.
Tightening torque: 22 ft.lbs 30 N-m 3 kg-m
Turn the Bolts 90~:
4. Make a mark on the head of each bolt.
5. Turn the bolts 90~ in the order shown in Step 3.
6. Turn the bolts an additional 90~ in the order shown in Step 3.
New Bolt (RF01 10 135A):
New Bolt (RF01 10 135A)
1. Apply engine oil to the seat of the head and the thread portion of the bolts.
2. Tighten the bolts as shown in Steps 3-6.