My wife was driving the 99 v70 xc last week when the engine shut down. Towed it to mechanic after it leaked all its coolant on the road who found a crack in the radiator. The engine runs with no coolant but is certainly misfiring. Compression in cylinder 3 is only 50 psi. I think I will pull the head, though I have no experience rebuilding an engine. Any help with how to diagnose the low compression will be much appreciated. Thank you

 

Need to do a cylinder leak test. Hopefully its just the gasket and not a warped head or cracked block.