P0174 on GMC

Same CPI spider injector issue as Chevrolet C/K. The 5.7L Vortec V8 spider assembly poppet nozzles clog and fuel lines crack.

Same intake gasket issue as the Astro van. The under-dash engine location makes this a more labor-intensive repair.

On the 4.8L, 5.3L and 6.0L Vortec V8s the exhaust manifold bolts - almost always the ones at the extreme front and rear of each cylinder head - snap from repeated thermal cycling, letting the manifold lift off the head. The classic symptom is a loud tick or 'exhaust leak' ticking at cold start that quiets as the engine expands and seals the gap. It is common enough on Savana and Express vans that fleet operators running 6.0L passenger vans report the front and rear bolts broken on both banks across their whole fleet. What makes this a van-specific problem rather than a generic truck one is access: the engine sits in a doghouse inside the cab, so the rear bolt near the firewall is extremely difficult to reach and the labor bill is far higher than on a Silverado with the same engine.

Direct injection engines do not spray fuel over the intake valves like port injection systems, allowing carbon deposits from oil and blow-by gases via the PCV system to accumulate on intake valve backs and ports. Over time, this buildup restricts airflow causing performance and efficiency loss. The 5.3L and 6.2L engines with direct injection are susceptible to this issue typically after 60,000-100,000 miles.

A common GMT800 Sierra problem is failure of the in-tank fuel pump module, often from worn pump motors or failed level-sender/module electronics. Owners report long crank, hard starting, loss of power under load, or sudden stall/no-start conditions, especially as mileage climbs. This issue is widely documented in owner forums and complaint databases across 4.3L, 4.8L, 5.3L, and 6.0L trucks.

The LML Duramax EGR (exhaust gas recirculation) cooler is prone to coolant leaks internally, allowing coolant to enter the intake manifold and combustion chambers. Coolant in the intake causes white smoke, rough running, and potential hydrolocking of cylinders. The EGR valve also sticks open or closed from carbon buildup, causing rough idle, black smoke, and check engine lights. The EGR cooler failure can occur as early as 60,000 miles on trucks used in stop-and-go driving. GM issued multiple TSBs addressing EGR cooler design improvements.

Sierra 2500HD trucks with the 8.1L Vortec big block and the 6.0L Vortec V8 shed exhaust manifold bolts, particularly at the front and rear ends of the manifold where thermal growth is greatest. The steel bolt corrodes and seizes in the aluminum-adjacent cylinder head interface and stretches through repeated heat cycles until the head snaps off, leaving the manifold loose against the head. The result is a cold-start exhaust tick that quiets as the metal expands, plus unmetered air entering the exhaust ahead of the oxygen sensors, which drives lean codes. This is a gasoline-engine failure - it does not apply to the Duramax.

Same intake gasket issue as the S-10 platform. The 4.3L Vortec V6 intake gaskets fail from heat cycling.

The GMC Suburban shares the same 5.7L Vortec intake gasket and spider injector issues as the C/K 1500. The larger vehicle runs hotter, which can accelerate gasket degradation.

The 2.4L LEA and LE9 four-cylinder engines in 2010-2017 Terrain are among the most reported excessive oil consumption issues in GM's lineup. Many owners consume 1 quart of oil every 1,000-2,000 miles. The root cause is inadequate piston ring tension combined with piston ring land fractures that allow oil to bypass rings into the combustion chamber. The problem was subject to class action lawsuits and GM Customer Satisfaction Programs. Burned oil causes spark plug fouling, catalytic converter damage, and oil pressure warnings. This is the same issue affecting the Chevy Equinox with the same engine.

Yukon XL V8 engines (notably 5.3L and 6.2L) can develop broken exhaust manifold bolts and/or warped manifolds, leading to an exhaust leak that is loudest on cold start. Owners describe a ticking sound that diminishes as the engine warms and the manifold expands. This is a well-documented GM truck/SUV issue in owner reports and service discussions for these engines.