This specification covers three classes of straight and formed coolant hose intended for use as radiator hose, heater hose and other flexible conduits for automotive engine cooling systems. Such products are intended to withstand the effects of circulating solutions containing glycols, small amounts of corrosion inhibitors and soluble oils, and operating under various pressure conditions at temperatures from —55 to 204 0C, and to withstand higher temperature environment than hose covered by specification GM6278M. The hose approved under the GM6149M specification is not recommended for incorporation into crimped coolant hose assemblies, such as those described in specification GM9O9OP.

Class I, Class U, or Class Ill may be specified for straight hose Class II and Class Ill are applicable to performed hose. Class I only is applicable to hump hose.

Note: See Appendix A for important information regarding bend radii and hose clamps to use with silicone rubber hose.