What to Check Before Buying a Used Full-Size Chevy: Buyer's Checklist

General Truck Discussion General Truck Discussion
1

Buying a used full-size Chevy or GMC is a smart move — they’re capable, parts are everywhere, and values hold well. But every generation has specific things to check before you hand over the money. Here’s your pre-purchase checklist.

Before You Go See the Truck

  1. Pull a vehicle history report (Carfax or AutoCheck) — accidents, title status, service history
  2. Check the VIN for recalls at the NHTSA website — all open recalls should be fixed at no cost
  3. Look up the generation-specific known issues — every era has its problems (see the era-specific threads here on FSC)
  4. Know the fair market value — use KBB, NADA, and recent local comps

Physical Inspection Checklist

Engine

  • Check oil level AND condition — gray/milky oil = head gasket or intake leak
  • Check coolant — rusty or low coolant is a red flag
  • Look for oil leaks on the engine, under the truck, on the ground where it parks
  • Listen for: ticking at idle (AFM lifters on 5.3L), knocking, excessive valve train noise
  • Check for blue smoke at startup (oil burning) or white smoke (coolant burning)

5.3L Specific (GMT900/K2XX)

  • Ask about AFM disable — if not done, budget for Range Device or delete
  • Check oil level after a drive — consumption?

Transmission

  • Check fluid condition — should be red/pink, not brown or burned-smelling
  • Test all gears — reverse, drive, all ranges
  • Feel for slipping, shuddering, or harsh shifts

Frame & Body

  • Check frame rails under the cab — rust is common in northern states
  • Inspect cab corners (lower rear of cab doors) for rust
  • Check pinch welds and rocker panels
  • Look under all door trim panels for moisture/mold

4WD System

  • Test all 4WD modes — 4HI, 4LO, back to 2WD
  • Listen for grinding or difficulty engaging
  • Check front CV boots for cracks/grease splatter

Suspension

  • Bounce test — more than 2 bounces after release = worn shocks
  • Check tire wear patterns — cupping = bad shocks; inside edge wear = alignment/ball joint issue
  • Grab each tire at 12 and 6 — play = ball joints or wheel bearings
  • Grab at 3 and 9 — play = tie rods

Test Drive Checklist

  • AC and heat — both working fully?
  • All power windows, locks, mirrors
  • Brake feel — firm or mushy? Any pulsation?
  • Steering — tracking straight? Any pull?
  • Highway test at 65+ — any vibration or shudder?
  • OBD scan — bring an Autel AL319 scanner and scan for codes before buying

Red Flags — Walk Away

  • Coolant in the oil (milky dipstick)
  • Frame rot (crumbling, not surface rust)
  • Transmission slipping or no 3rd/4th gear
  • Rebuilt title with no documentation of repairs
  • Seller won’t allow a pre-purchase inspection by a mechanic