There are a few reasons why you have low/no compression on any given cylinders.
Could be due to bad piston ring, bad valve, dropped valve seat etc. It can also be due to a blown head gasket.
You mentioned it is smoking, what color is the smoke? Typically, with blow head gasket you will have white smoke out of the tailpipe.
The best course of action would be to take a look at each possibility to figure out what is going on.
If you have a blown head gasket, it will allow oil and coolant to mix, and you will have milky white color oil.
Take a look at this guide, it covers the typical issues:
Please let me know if you have any questions.
Images (Click to enlarge)
Saturday, February 26th, 2022 AT 12:51 PM