Where is the thermostat on a 2001 Nissan Quest ?

SOURCE: Replacing The wiper arm on a 2001 Nissan Quest

Removing and replacing the wiper arm is a very technical and delicate affair. If you don't handle with care you may get your windscreen broken. I advice you let an expert do this for you.

Good luck.

SOURCE: My 2001 Nissan Quest temp gauge rise to hot, cools then get hot

You better not be driving your car overheating like that and shutting off on you! It sounds like you've most likely lost all your coolant due to a leak of some sort, and your engine is overheating. I would take the vehicle to a shop make sure you don't have some kind of major coolant leak. They'll also want to do a "block-check", which is a fluid that can detect combustion vapors in the coolant, that would indicate you've blown a head gasket due to overheating. It's very bad for an engine to run without coolant, even for 10 minutes. I'd have the vehicle towed in unless the shop is right around the corner. If you'd like to check your coolant level yourself, make sure the engine is cold or at least the vehicle has been off for an hour. Checking the overflow tank level may not be good enough. You'll have to remove the radiator cap and determine if you've got any coolant in the radiator. If not use either regular pre-mixed green coolant, or if you have non pre-mixed dilute it to a 50/50 ratio coolant and water. I wouldn't continue to drive your van with it acting up like it has until you can get it checked out.

SOURCE: identified leak in intake manifold

I'am sort of missing something here

Was the radiator blocked or replaced as a guess ?
The thermostat i understand
The heater core by pass i don't,what does that prove ?

The shop says - intake manifold hose.

A hose causing overheating,explain that one.

The finally question
What is your question? Did the repair shop
get lost and ask you for help?