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.Google+
Car Problem Reports
Infiniti QX56 Exhaust manifolds crack and make loud noise on acceleration
Infiniti QX56 Problem
Average Mileage: 97,791 mi (65,000 mi - 135,000 mi)
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
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
Visitor, 2005 Infiniti QX56, 130,000 mi
Started ticking when started car and when it warmed up it would go away. Now it's horrible. I feel like I drive a hoopti not a luxury vehicle. If this people are reporting this then why isn't this a recall. Also why in the hell would you make a manifold out of aluminum in the first place. It doesn't expand and contract with heat like steel. Come on. You are suppose to engineers.
Visitor, 2004 Infiniti QX56, 82,000 mi
not yet fixed, was informed by dealership about both exhaust manifolds cracked 8 months ago (4/13)
Visitor, 2006 Infiniti QX56, 135,000 mi
I am very upset to find out that my truck has cracked exhaust manifolds and the dealer wants to charge over 3,000 dollars to fix. To me seems like this is common at some point with alot of QX56 SUVs, my friend who also owns the same model different year has experienced the same problem. Infiniti needs to recall this issue, to me its a manufactures defect. I want to trade-in my truck now and thats sad because I love it, it just isnt loving me in return...
Visitor, 2006 Infiniti QX56, 65,000 mi
Still have problem. Leak on the passenger side of vehicle. I was told crack can be easily welded. It's between the 3rd and 4th cylinders.
Visitor, 2007 Infiniti QX56
I took it in today, and the muffler shop wants 1700 before tax. when i got the vehicle back the navigation screen is not working. it stays off and has no function, not even the radio works.