Compression test won’t tell you if it’s a bad head gasket necessarily, but if it’s good then valves are in good shape. With an unknown engine there is not really a good path other than running it for a bit then pulling plugs and look for steam cleaning

"Steam cleaning" is great test. Likely this car has a huge leak somewhere. Ideally you would remove all spark plugs. Pressurize the coolant system and with articulate borescope look into each cylinder for a leak. The fact that it was rebuild does not prove anything. Who did it, what equipm...

If the work was done by "volvo shop" I would expect them to stand behind their product and for modest diagnostic fee to look at your engine and hopefully tell you what is wrong with it 100%. In terms of tools like borescope- it is a great tool and if you have something that works, I would ...

When you will sort out this issue, look at engine mounts. The top one is for sure is done. It is great that exhaust gases are not detected in coolant, but lots of 2010 Priuses have the leaking headgasket in the similar fashion. Appoud all your work and research. Pressure testing system and borescope...

Pardon me asking: was the exhaust gas test performed on warm working engine that reached operating temperature(ideally after a test drive)? The video will not do the justice to this issue since we not yet able to transmit the smell. It may look like "ok working older engine". Another test ...

So it looks like you are missing a connecting arm from the dangling part to the ball knuckle to the right of it. I believe this is the part: https://www.volvocarstorontoparts.ca/p/Volvo_2006_V50-25l-5-cylinder-Turbo/Headlight-Level-Sensor-Front/42830537/30659018.html You can magnify the picture of t...