To check the
cooling system. There's a kit that has a fitting that goes in place of the radiator (header tank) cap. It has a means of pressurising the
cooling system and a guage. The leakdown test simply is seeing if the pressure is maintaned over time. Advance auto has a tool loaner program if there's one in your area. I saw a
diesel compression test kit last time at harbor freight. $60 or so. Simple testing tools tell the whole story. Also simple visual checks of fluids. White in
oil indicates water, black or oil in water indicates crack or leak somewhere