I’ve recently purchased a 2007 Lexus ES 350 a 115k miles ,
it was over heating jumping up and down Seller said was temperature sensor , I went to buy with mechanic(fired) he said it is just water pump if I change it will be a good buy ,

after changing the pump , it was still overheating he suggested changing the coils because it was misfiring and giving codes for many misfires, and on cylinders 1, and 2 or 4 after changing them it still continued and the computer didn’t accept all of the coils ,

so I took it to a shop where I was informed that is sign of a head gasket problem ... after going on YouTube I see it is likely that can be changed on the engine and then there are other problems with it requiring more than just the head gasket .... is it worth it ? He gave me a reasonable quote considering the 3-4K I would probably hear from a Lexus dealer

 

Sounds like nobody is diagnosing the problem. They all seem to be guessing. If you bought the car then you'll need to spend some more money to have someone find the problem. There are various ways to check for head gasket leaks and any good shop should be able to tell you. Once they determine the problem then you will get an estimate on how much it would cost to fix it. If you have not purchased the car yet then move on and fine one that doesn't have any issues.