The thermostat is located in the top hose inlet on the engine. The inlet is on the rear of the engine at the firewall.
Follow the top radiator hose at the end of that hose is the thermostat housing. The thermostat is located under the thermostat housing.
Do you have a diagram of the coolng system and thremost location?
The thermostat on your 98 gmc is located in the intake manifold where the upper radiator hose connects to the intake.
The thermostat is located on the top of the engine, connected to the upper hose. The thermostat housing is turned sideways (compared to U.S engines, i.e. Chevy 350, etc.)
follow the top radiator hose to the intake manifold... there will be an elbow its connected to. take off the elbow and under it will be your thermostat.
Usually located in the removable housing at the engine end of the upper radiator hose
I have a 98 626es v6, thermostat is located under air filter housing on the right side of the engine if you are standing at the front of the car facing the engine
The thermostat is located behind the alternator on the driver side of the engine. Follow the lower radiator hose back to the block.
I have a 2002 Subaru Impreza Outback and it have the thermostat on the right bellow the engine. You can fallow the hose from the radiator that goes to the bottom of the engine.
Follow the top radiator hose down to the water outlet on the engine. The stat is in there.
Usually located in a removable housing at the engine end of the upper radiator hose
k