Bulletin No. 1.20-2 Group No. 1.20 December 10, 1998 Page 1 of 2

HEAD GASKET FAILURES

HEAD GASKETS ARE DESIGNED AND MANUFACTURED

TO PERFORM AT 100% RELIABILITY. SO WHY WOULD THEY FAIL?

HERE’S A FEW REASONS.

Head gasket failures seem to be more prevalent after the first time the head has been removed. This is especially true since the introduction of substitute materials to replace asbestos. As a result, materials and assembly procedures have changed to assure acceptable performance of head gaskets. The following is a list of possible causes for failures.

1. LINER STAND-OUT: Cylinder liner height above block must be to specification. Also, no more than 0.002 in. (0.05mm) variation between adjacent cylinders.

2. IMPROPER PREPARATION: Clean, dry, oil free deck surface without adhesives are essential. It is a good idea to restore the threads and pre-lube cap screws before installing.

3. IMPROPER ASSEMBLY: Locating head with aid of guide studs prevents damage to gasket while aligning bolt holes.

4. TIGHTENING SEQUENCE: Some new procedures have been adopted. Refer to current component technical manual.

5. HEAD CAP SCREW TORQUE: Four systems in use for Waterloo block. Depends on bolt length and design. Refer to technical manual.

6. NEW CAPSCREWS: Use new head capscrews if damaged or previously taken to yield.

7. OVERHEATING: Heating damage to gasket can cause failure.

8. OVERSPEEDING: Increased cylinder pressure can fail gasket due to overspeeding engine under load.

9. OVERFUELING: Increased power increases cylinder pressure (BMEP) which can damage gasket.

10. HEAD AND BLOCK FLATNESS: Check face for straightness both lengthwise and across the width.

11. INCORRECT RESURFACING: Micro-finishing according to specifications.

Bulletin No. 1.20-1 December 10, 1998

Page 2 of 2

12. SHIPPING DAMAGE: Head gaskets can be easily damaged by improper handling during shipment (bending). Inspect carefully.

13. BAD GASKET: It is possible to have a manufacturing defect. Inspect new gaskets carefully.