Hi, took it to the shop for shaking and turning off (kia sedona 2008) mechanic changed plugs and coils, said cam seals were broken but not worth to change them. He recommended next work should be changing engine. A few weeks later I notice it overheats and leaks coolant from under engine and as soon as I refill with coolant, it leaks from bottom of engine. Should I change engine?
If you have driven it more than a couple miles while it was overheating there is a chance that permanent damage has been done internally. Without looking at it or listening to it it is hard for me to give a proper opinion. Any knocking noise would indicate internal damage or running rough.
You may be able to identify the leak and fix it. Here is a video on just how to do that with a coolant system pressure tester.