follow the top radiator hose it will lead to the top of engine block you will have to remove air breather and other attachments will need 11, 13 metric sockets under air regulator is metal radiator line two bolts( above type) removes this pipe. The thermostat is behind metal pipe, you must also loosen two small hose clamps to the heater core pipe good luck
do i need to change the manifold when replacing thermostat
yes
100
R134A
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On the muffler
You can't, they are bolted in
It's under the throttle body housing. I'm looking for an answer on how to take the housing off to get to the thermostat
Yes, on a 1998 Chevrolet Lumina with a 3.1L engine, you typically need to remove the throttle body to access the horizontally mounted thermostat. This involves disconnecting various components and hoses connected to the throttle body before it can be removed. Make sure to follow a repair manual for detailed instructions and precautions to avoid damaging any parts.
To replace the thermostat on a 1999 Chevrolet Lumina, first, ensure the engine is cool and disconnect the battery. Drain the coolant from the radiator, then remove the upper radiator hose connected to the thermostat housing. Unbolt the thermostat housing to access the thermostat, replace it with a new one, and reassemble by reversing the steps. Finally, refill the coolant and check for leaks.
Replace the thermostat.
Read the owners manule.