If you follow the lower/ bottom radiator hose from the radiator to the left front of the engine you will see were it clamps onto a housing that's bolted with 3 bolts to the water pump. It is behind that housing.
It is on the left or right side of the truck by the fender well on the engine.
Usually in a removable housing at the engine end of the upper radiator hose
The thermostat is located on the engine on a 1998 GMC Sierra 1500 standard. The thermostat can be found by following the upper radiator hose directly to the thermostat,
The thermostat on your 98 gmc is located in the intake manifold where the upper radiator hose connects to the intake.
Drain the water from your 1997 GMC Yukon cooling system. Remove the water supply hose. Remove the thermostat housing retaining bolts. Remove the old thermostat and replace with the new thermostat.
What is a thermostat light?
You remove the old thermostat and install a new one.
Help! where is the thermostat located on a 2005 sienna?
http://www.extendedgmwarranty.com/owners-manual/gmc/2005-GMC-Yukon.pdfadobe acrobat required
The 2005 GMC Yukon has 16 valves.
The 2005 GMC Yukon has a V8 engine.
The 2005 GMC Savana has 12 valves.