u/berndog927

Preface; do not have experience working on cars, bought this last year to enjoy and learn how to fix my own car.

Had the car into the dealership for a free oil change, and they told me that the thermostat gasket is leaking. Bought an OEM thermostat and gasket from the dealer and set out to do my first repair.of the year. When I took the thermostat housing off, I saw that there was no thermostat at all (it has an aftermarket radiator, see the picture). I added the new thermostat, the new gasket, added coolant, and then took it out for a drive to get it up to temperature to check for leaks. The total trip was about 2 miles. At a mile and a half, I started to lose power. Got it into the driveway and popped the hood. The engine bay was hot, but the temp gauge on the car was below half. Idling in the driveway, the car started to sputter. It would not rev , then sputtered and I shut it off. This doesn’t seem like a thermostat issue to my novice self.

I know that there are at least 2 other things wrong with the car. I have a P0204 excessive flow code. It’s been there for a while. Recently, the battery light came on. Believe my alternator is taking a dump. I am not throwing any other codes.

Thoughts on the direction I should start looking to fix this beast? As always, I appreciate your thoughts and help.