Low compression

Hello good I have a 1995 Renault Laguna 2.0 Gasoline the mechanic has told me that it lacks compression and that you have to disassemble the cylinder head to see if it is valves or segments. It exists any way to check if they are the segments or are the valves without disassembling the cylinder head? . Anra asks if it is true that you can clean a cylinder head, piston piston pouring a little oxygenated by the admission, or maybe find something else.If it is so please explain it

Indeed, if you can know if the compression escape is by valves, rings, joint, the mechanics have a -Analizer of compression leaks- (non -compressor)
with that analyzer it is verified where the leak exists, either by admission valve, escape, rings, joint.

I don't know about the hydrogen peroxide, what I have seen are decarbonizing that help clean the accumulated carbon (carbonilla).

Hello, there is a way of knowing if they are valves or rings, you have to take the compression of the 4 cylinders, write them down then you put a little oil to the cylinders (about 10 cc +o-), you turn the engine with the start about 5 seconds and return to take compression if it does not vary too These will increase the rings (eg: 150PSI YC/A 180 or more) because of the water is true but you have to do it carefully since you can cause a hydraulic wedge, that you are lucky.