I didn't hear any hissing. Does the power steering work? keep an eye on that fluid level for a while. Check your radiator fluid levels beware of over heating. maybe you sprung a leak somewhere in the radiator. 1 to 2 minutes (or less) of overheating can warp these alluminum heads.

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2002 BMW X5 3.0
2006 Ford Explorer 6 cyl
1998 VW Jetta 2.0 GLS
2004 Honda VTX1800C 100hp 97 lb of torque