GMW GMW17377 PDF

Note: Nothing in this standard supercedes applicable laws and regulations.

Note: In the event of conflict between the English and domestic language, the English language shall take precedence.

Purpose/Material Description.

This standard describes the materials and performance requirements for fuel and oil vapor resistant gaskets, used in automotive engine cover applications. Engine Oil Pan gaskets are specified in GMW3083. The constructional and component features covered by this commodity standard are described in 1.1.1 and Table 2. Do not use this document for applications outside the Purpose and 1.3 of this standard.

Materials covered by this specification are divided into classes and types of oil and fuel resistant elastomers.

The classes are categorized by the material family of elastomers ACM, HNBR, FKM/FPM and AEM. The types are categorized based on gas engine or diesel engine and oil or fuel immersion and temperature range. A temperature range is designated for each class and type of material. Table 1 describes the Class (B, C, etc.) of elastomers and Type 1, Type 2, Type 3, and Type 4 meeting the designated application (gasoline or diesel engine and oil or fuel immersion) and temperature range. Part performance requirements are in 3.9 and Tables 5, 7, 9, 11 and 16. See Remarks in 1.4 through 1.4.3.

Part Constructions. Construction usage code letters that apply to this standard are listed in Table 2.

Code letters designate specific tests that apply only to that construction and/or material for detail drawing specifications. See Section 8.

Symbols.

Plastic and rubber parts shall be marked with a symbol to designate the type of material from which the part was fabricated for the purpose of collection and handling of parts for recycling.

Elastomer Marking Symbol. Mark rubber parts weighing more than 200 g per GMW3116.

For example:

• Fluorocarbon >FKM<.

• If practical, place the part number, your company Association for Rubber Product Manufacturers (ARPM) letter code, cavity number and mold date (mm/yy) on the part. Characters shall be visible and not in a location that adversely affects form, fit, or function.

Plastic Marking Symbol. Mark plastic parts weighing more than 100 g per GMW3116.

For example:

• Polyamide with Glass Fibers >PA-GF30<.

Applicability.

See Table 1. Only parts fitting the scope and application may use this specification. Because of the differences in engine cover system design within GM, covers including crankcase vapor function shall be tested to Tables 14 and/or 15.

Remarks.

Approved compound properties for each type of elastomer are listed in Tables 4, 6, 8, 10, 12, 13, 14 and 15. Table values by type are a compilation of data from multiple approved compounds and hardness ranges.

Plastic carrier (Cp) gaskets with coolant ports require heat and hydrolysis stabilized nylon per GMW16270. Gaskets without coolant ports may use heat stabilized nylon per GMW3038. See Table 2.

Fluorocarbon Behavior in Fuel Diluted Oil.

For methanol and ethanol diluted oil conditions, the percent fluorine level (higher is desired) is most important. In biodiesel diluted conditions with oil, the cure type (peroxide) and no metal oxides take precedence over percent fluorine. The metal oxides have no significant impact on fluorocarbon (FKM) Type II, III, IV, or V peroxide cure systems. There is no impact on color choice for carbon black filled and mineral filled systems. There are variations in what are called metal oxides. For example, ceramic type mineral systems are metal oxides and are being used successfully in mobility systems where zinc, calcium or magnesium oxides would not be successful in that application.

This standard contains provisions for gaskets with crankcase vent function (see 3.1.7).

Select the class and type intended for the end use needs. Table 1 temperatures represent the continuous operating range for all approved compounds in that class as measured in air at atmospheric pressure.

Compounds Represented in Tables. The majority of elastomer compounds represented in the current property tables are for sealing metal to metal joints where micro-hardness ranges from 55 International Rubber Hardness Degrees (IRHD) to 75 IRHD. Plastic covers use lower hardness gaskets where part micro-hardness ranges from 40 IRHD to 60 IRHD. Adjustments in existing tables or new tables may be required as softer gaskets for metal to composite cover joint applications are developed.

Compression Stress Relaxation. Per GMW17113, deflection is 15% for manual and continuous.

Note: Only one (1) method, manual or continuous, shall be run. Only one (1) method is required, not both methods. For manual, there is the option of running 35% deflection in addition to the required 15%. 15% deflection replicates Least Material Conditions (LMC), and 35% replicates Most Material Conditions (MMC).

Thermal Cycle Continuous Compressive Stress Relaxation, 15% deflection, GMW17113 BC6AD0 required test for all classes, all types with TR10 at or below -25 °C in addition to testing described in 1.4.6.