2004 GMC SAVANA

Typical onset: 120,000-180,000 mi

Symptoms: Excessive oil consumption (quart per 500-1000 miles), Blue smoke on startup or acceleration, Rod knock or piston slap on cold start, Loss of compression in one or more cylinders, Check engine light with misfire codes

Fix: The 6.0L Vortec from this era is notorious for piston ring failures and oil consumption due to weak ring design and cylinder bore wear. Many owners band-aid it with frequent top-offs until catastrophic failure (spun bearing, thrown rod). Proper fix requires engine rebuild with aftermarket rings or short block replacement. Budget 18-25 hours labor for in-chassis rebuild, 12-16 hours for short block swap if you're pulling the engine.

Estimated cost: $3,500-6,500

Typical onset: 80,000-150,000 mi

Symptoms: Transmission slipping or delayed engagement, Pink or milky fluid in coolant reservoir (coolant in trans), Brown coolant (trans fluid in coolant), Transmission overheating, Rusted or weeping steel cooler lines at radiator connections

Fix: The 4L80E transmission cooler lines rust through or the internal radiator cooler fails, cross-contaminating coolant and ATF. This kills the transmission within days if not caught. If contamination occurs, you need full transmission rebuild/replacement plus radiator replacement and complete flush of both systems. Prevention: replace steel cooler lines with stainless at first sign of surface rust. If caught before contamination, lines alone are 2-3 hours labor. After contamination, transmission R&R is 8-12 hours plus rebuild costs.

Estimated cost: $350-650 (lines only preventive) / $3,200-5,500 (full trans rebuild after contamination)

Typical onset: 90,000-140,000 mi

Symptoms: Coolant seepage at front or rear of intake manifold, White residue or dried coolant on block under intake, Rough idle or high idle, Small coolant loss with no external leak visible, Possible misfire codes if coolant enters cylinder

Fix: The plastic composite intake manifold gaskets deteriorate and leak coolant externally or create vacuum leaks. Requires intake manifold removal, new gaskets (use Fel-Pro or OEM, NOT Dorman), and thermostat/hoses while you're in there. On the 6.0L this is a 5-7 hour job due to van packaging and accessory removal.

Estimated cost: $650-1,100

Typical onset: 100,000-160,000 mi

Symptoms: Hard starting or extended crank time, Engine stumble or stalling under load, Fuel smell near rear of vehicle, Visible rust or holes in filler neck, Check engine light with low fuel pressure codes

Fix: The in-tank fuel pump wears out, and the steel fuel tank filler neck rusts through (subject of NHTSA recall but many not fixed). Pump replacement requires dropping the massive tank, which on a cargo van with cage/shelving is a nightmare—budget 4-6 hours labor. Filler neck replacement adds 2 hours. These often happen together since you're already dropping the tank.

Estimated cost: $800-1,400

Typical onset: 70,000-120,000 mi

Symptoms: Clunk when shifting from Park to Drive or Reverse, Vibration at idle in gear, Excessive driveline movement visible under throttle, Transmission appears to sag when viewed from underneath

Fix: The rear transmission mount (crossmember mount) collapses from the weight of the 4L80E and constant load cycling in commercial use. Replacement is straightforward—support trans with jack, remove 4 bolts, swap mount—about 1 hour labor. Use OEM or quality aftermarket (Energy Suspension polyurethane holds up better for heavy-duty use).

Estimated cost: $180-320

Symptoms: Soft or spongy brake pedal, Brake pedal slowly sinks to floor, Visible rust or wetness on steel brake lines along frame rails, Brake fluid loss with no visible wheel cylinder leak, ABS light on with low fluid

Fix: Steel brake lines rust from the inside out in rust-belt areas, and the master cylinder can fail (internal seal leak causing pedal fade). Two NHTSA recalls for hydraulic brake issues on this platform. Line replacement typically involves 6-10 sections and requires bending/flaring new lines—4-8 hours depending on rust severity. Master cylinder is 2 hours with bleeding. Do NOT defer this.

Estimated cost: $400-900 (master cylinder) / $800-1,800 (full brake line replacement)

Typical onset: 120,000-180,000 mi

Symptoms: Shifter feels loose or disconnected, Transmission gear doesn't match shifter position, Cannot shift out of Park, Shifter moves freely with no resistance

Fix: The column shift cable stretches or the plastic bushings at the transmission end disintegrate (subject of NHTSA recall). This leaves you stuck in gear or unable to confirm what gear you're actually in—safety hazard. Cable replacement is 2-3 hours: remove column covers, disconnect at column and trans, route new cable. Use OEM cable, not aftermarket junk.

Estimated cost: $280-450