Report: Exhaust manifolds crack and make loud noise on acceleration
Infiniti QX56 Problem
Average Mileage: 91,000 mi (72,000 mi - 119,000 mi)
It is not uncommon one or both of the exhaust manifolds to crack resulting in an exhaust leak. Symptoms will begin as a ticking type noise noted on acceleration when the engine is cold.
The exhaust manifolds have built-in catalytic converters. Excess heat causes early ones to crack. Loud popping noises are heard on hard accerlation, like merging onto a busy freeway. Your test drive should include merging onto a freeway. Both of mine were replaced under warranty. I recently (Jan. 2011) received a letter from Infiniti that the warranty on these had been extended to 8 years/80,000 miles because they are an "emissions" component.
Visitor, 2005 Infiniti QX56, 119,000 mi
Same issue as everyone else who posted here. We were out of warranty when it was discovered and the dealer wanted over $2800 to repair.
Visitor, 2005 Infiniti QX56, 90,000 mi
Exhaust manifolds were severly cracked and popped when accelerting. Nissan wanted to charge $4k plus. Midas sent them to a machine shop, complete fix at $400 (sigh of relief).
Visitor, 2006 Infiniti QX56, 72,000 mi
manifold cracks and engine starts making noise like its a diesel engine upon acceleration and startup
alomst exact same problem; took in to replace a "sensor" and EGR valve and was told BOTH manifolds were cracked and cost to repair was going to be $2,800!!!! i was also told that this was VERY common in the QX line of vehicles becuase they are made from stainless steel and not cast iron and the SS does not hold up to the constant heating and cooling they experience. sure seems like INFINITI would do the right thing and own up to a manufacturing defect and fix this problem out of THIER pocket