I was driving our 2002 Blazer 4x4 4.3L yesterday. I had to accelerate quickly to merge when a large cloud of smoke blew out of the exhaust ! Then steam came out from under the hood. Temp guage then climbed quickly. I pulled over & seen no coolant in the system. I tried to put more in but it immediately rushed out of the backside of the engine. My Blazer driving day was done so I called the hook. I think it is the intake manifold gasket or head gasket, but how do I check when coolant rushes right out @ once ( hard 2 see back there ). How 2 differentiate between intake & head gasket & then which head gasket is it ? What types of sealants would I use on the threads of say intake bolts & head bolts ? Especially the ones that thread into the coolant jacket areas ? Also, what would I set the torque on the nuts in the 12 rockers to set the hydraulic roller rocker valves ( how to set up valves) Is it just torque all to 20 ft-lbs. Would you have to rotate the engine @ any point to set up valves?