1996 300E Diesel
 

Realize that I need new glow plugs but I got through the cold winter of New England. Car was kept in garage. Now this spring car starts but before engaging there is a like a banging sound when it starts and it emits smoke. Any thoughts on what that banging sound is? Hope it is not serious. With 149000 miles car still gets about 35 miles per gallon on highway and about 26 in city. A