The rubber ends of the crankcase vacuum scavenge and breather hoses on my K5 (2.5l) engine are brittle and splitting (I recall Conglomerate warned that this was a common problem).
If you have replaced yours, what have you replaced them with? Genuine parts, or some OTS hose with better heat resistance?
If you have replaced yours, what have you replaced them with? Genuine parts, or some OTS hose with better heat resistance?