Alert: Warmup Popping And Broken Head Stud
 

Many threads, especially as the temps drop, deal with popoff valve popping during warmup from a cold start on CIS cars. The usual advice includes checking mixture, WUR, AAR, cold control pressure, vacuum leaks, and others.

I have recently encountered another probable cause. As temps dropped, I started to experience these symptoms. During a valve adjustment, we discovered a broken Dilivar head stud on number 4 cylinder. As the parts separated, air entered and was leaning that cylinder, causing the popping. As the engine expanded with heat, the gap closed and the popping stopped. There was never any apparent puffing of the exhaust. Needless to say, I am now replacing all the lowers with steel studs.

This may be old news to some, but for me, this represents a new item to check when experiencing warmup popping.

Just curious how you located the broken stud? Was it apparent from pulling the lower valve cover? What kind of cost is involved in replacing with steel? I am potentially buying a 77 with 126K and dilivar studs installed at 81K. Also- did you install a remote oil cooler?