head gasket on 1995 Chevrolet Astro

how do i know if i need to replace my head gasket? It smokes now bluish white smoke out of the tail pipe. Also it goes about 10-15 mph in drive mode until it hits 35 on the gauge it gets its speed after that? help me please

1 answer
Head gaskets are not common failures on Astros. The engine could simply be shot.