Follow the upper radiator hose back to the engine block. There will be a cover plate with bolts holding it to a housing. This housing contains the thermostate. It has to be taken apart with the 2 possibly 3 bolts and a gasket. A LOT of fluid will pour out when you break the seal and open it. It maybe very difficult to get out without special tools to get to the bolts. You will then need to reseal it with rtv or supplied gaskets. I prefer ultra copper rtv.
To replace the thermostat on a 2002 Nissan Altima first drain out the coolant. Then proceed the to locate the thermostat housing which is by the engine compartment fuse box. Unbolt the housing and replace the thermostat.
The thermostat on a 96 Nissan Altima is located on top of the engine at the upper radiator hose. It is contained under the thermostat housing which holds it in place.
The 2003 Nissan thermostat is located inside of the thermostat housing. You can follow the bottom radiator hose directly to the thermostat housing.
thermostat location on 2003 Nissan altima
On a 1997 Nissan Altima the water pump should be mounted on the front of the engine. It is right at the thermostat housing.
how do you replace the ac evaportator
how to replace an altinator in a 2005 nissan altima
The 1997 Nissan Ultima thermostat is located on the front of the engine. You can follow the water supply hose from the radiator to the thermostat housing.
I found lots of technical info at http://www.altimas.net/tsb/ Look at bulletin number NTB02-047. This explains how to troubleshoot poor heater performance and it gives a procedure for replacing the thermostat. what is a pilot converter
Please help me locate the thermostat on a 2000 Nissan altima
How do you replace a water pump on a 98 nissan altima?