The 2017 K900 is Kia's flagship luxury sedan sharing the platform with Genesis/Hyundai products. While loaded with features and surprisingly reliable for its class, the 5.0L V8 variant suffers catastrophic engine failures due to bearing/piston issues, and both engines share transmission cooling and mount weaknesses.
5.0L V8 Tau Engine Catastrophic Bearing/Piston Failure
Occasional · high severityTypical onset: 60,000-100,000 mi
Symptoms: metallic knocking from bottom end especially on cold start, oil consumption increases suddenly, metal shavings in oil during change, loss of power and check engine light with misfire codes, complete engine seizure in worst cases
Fix: Rod and main bearing failure leads to piston/cylinder wall damage requiring complete engine rebuild or replacement. Most shops recommend reman long block over rebuild due to core damage extent. 25-35 hours labor for R&R plus machine work if rebuilding. This is the Theta/Tau V8 recall-adjacent issue manifesting outside official recall parameters.
Estimated cost: $8,000-15,000
Transmission Oil Cooler Line Leaks and Cooler Failure
Common · medium severityTypical onset: 70,000-110,000 mi
Symptoms: transmission fluid spots under vehicle near radiator area, transmission running hotter than normal, burnt transmission fluid smell, harsh shifting when fluid level drops, pink/red coolant contamination if internal cooler fails
Fix: Hard lines corrode where they meet the cooler, or internal cooler fails allowing coolant/ATF cross-contamination. External line repair is 2-3 hours, but internal cooler failure requires radiator replacement plus complete transmission flush (4-5 hours). If coolant enters trans, you're looking at trans rebuild.
Estimated cost: $600-1,200 (lines only), $3,500-6,500 (if trans contaminated)
Transmission Mount Failure (Rear Mount)
Common · low severityTypical onset: 50,000-90,000 mi
Symptoms: clunk when shifting from park to drive or reverse, vibration at idle in gear, excessive driveline movement felt during acceleration, visible cracking or separation of rubber mount
Fix: Rear transmission mount deteriorates from heat and weight of the 8-speed auto. Replacement requires supporting transmission and removing crossmember. 2-3 hours labor. Common enough that you should inspect this during pre-purchase.
Estimated cost: $400-700
ABS Module Failure (Related to NHTSA Recalls)
Occasional · high severitySymptoms: ABS and ESC warning lights illuminated, loss of ABS function with hard pedal feel, brake pedal pulsation during normal stops, false activation of stability control, complete loss of power brake assist in rare cases
Fix: Internal short in Hydraulic Electronic Control Unit (HECU). Two recalls issued but some units still fail outside parameters. Replacement requires brake system bleed and programming. 3-4 hours labor. Check if recalls 19V-702 and 20V-426 were completed before buying.
Estimated cost: $1,800-2,800 (if out of recall coverage)
3.8L V6 Head Gasket Seepage
Occasional · medium severityTypical onset: 80,000-130,000 mi
Symptoms: oil seepage visible at head/block mating surface, coolant smell from engine bay, minor coolant loss without visible external leaks, white residue on coolant cap, rough idle when cold if coolant entering cylinder
Fix: Lambda V6 develops external head gasket weeping more often than internal failure. External seepage can be monitored but eventually requires head gasket replacement both sides as preventive measure. 14-18 hours labor including head resurfacing if needed.
Estimated cost: $2,800-4,200
Fuel Filter Clogging (High-Pressure In-Tank)
Occasional · medium severityTypical onset: 90,000-140,000 mi
Symptoms: hesitation during acceleration, lean codes and fuel trim adaptation limits reached, hard starting after sitting, loss of power under load especially uphill, fuel pump whining more audible
Fix: In-tank high-pressure filter clogs from fuel quality issues or tank sediment. Requires fuel pump module removal from tank. Kia considers this lifetime but it's not. 3-4 hours labor including tank drop if necessary for access.
Estimated cost: $500-900
The 3.8L V6 is the safer buy for a used K900, but the 5.0L V8's engine failure risk makes it a gamble unless you have comprehensive records and low miles — otherwise, walk away from V8s without warranty coverage.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.