Thermostat Problem and Water Leakage

Hello everyone. I took my last vehicle to the master and he said he saw water marks and mold on the bottom of the engine, he said that the thermostat should be changed. He said if there is a water leak, let's see it again. Now I noticed that there is a leak like half a liter for 2 months. Does anyone know if this problem really requires a thermostat change, thank you

Hello, if the leak is around the thermostat, of course it should be changed. Have a nice day :)

Thank you. I went to the master today and changed it.

I changed it today too. Finding the right thermostat proved difficult. Some of the ends are long, some are short. I had a thermostat (650 TL) fitted to the Ford vehicle, the old one was the same. The thermostat I bought from a place I trust from the internet (320 TL) did not fit. I gave labor at 100. How much have you changed?