Two problems related to engine exhaust system have been reported for the 2005 Chevrolet Suburban. The most recently reported issues are listed below.
Exhaust manifold bolt head broke off. 1st bolt initially then second bolt next to it broke as well. No work has been done to motor or aftermarket parts added that would affect this part and create failure. Exhaust gas enters the underhood area . The exhaust makes a black plume up side of motor. Concerned that the leak could worsen leading to exhaust fumes entering passenger compartment. I do not know if the escaping hot exhaust gas could lead to fire. In addition, I would think the epa would be concerned about effects on vehicle emissions. The leaking exhaust gas is not passed thourgh the catalytic converter. The leaking gas is also not sampled by the oxygen sensor and could effect the sensors input to the vehicle computer. I see by doing simple internet searches on this topic that the bolt failure and leaking exhaust manifold problem is widespread. I have not repaired the broken bolts yet.
This is a pre-cautionary complaint as a result of my shock regarding gm's 8. 1l engine in the Suburbans. Also would apply to silverado hd as well. The vehicle is using excessive oil which to my surprise gm says is normal. Oil usage is 1. 25 qts per 2000 miles and gm indicated that the vehicle could use as much as 1qt per 1000 miles (assuming 10 miles to the gallon). The concern is regarding emissions durability and indirect failures as a result of this oil loading into the exhaust and catalytic converter. Gm would not provide details to me but, industry norms are assuming worst case 1/2 of this level of expected oil usage. Gm was unconcerned and has a bulletin for their dealers stating this. I feel this should be investigated both from a safety standpoint for potential engine failure and for emissions durability and environmental compliance.