The 2007 Buick Terraza is a GM U-body minivan sharing architecture with the Uplander/Montana/Relay. It's plagued by catastrophic 3.5L/3.9L engine failures from inadequate intake gasket sealing and transmission cooling issues — budget heavily for both or walk away.
Intake Manifold Gasket Failure Leading to Engine Destruction
Common · high severity
Typical onset: 60,000-120,000 mi
Symptoms: Dexcool coolant leaking externally at intake manifold valley, White smoke from exhaust, sweet smell, Coolant mysteriously disappearing without visible external leaks, Rapid overheating or milky oil indicating head gasket failure secondary to coolant intrusion, Catastrophic bearing failure from coolant-contaminated oil
Fix: Early catch: intake manifold gasket replacement, 6-8 hours labor. If ignored, coolant enters cylinders causing hydrolock or dilutes oil leading to bearing failure — then you're looking at short block replacement (25-30 hours) or used engine swap (18-22 hours). This is THE killer on these 3.5L/3.9L engines.
Estimated cost: $800-1,200 (gaskets only) or $4,500-7,500 (engine replacement with used low-mile unit)
Transmission Oil Cooler Line Failure and 4T65-E Transmission Damage
Common · high severity
Typical onset: 70,000-130,000 mi
Symptoms: Transmission fluid leaking from cooler lines at radiator connections, Pink/red fluid mixing with coolant in overflow tank (internal radiator leak), Harsh shifting, slipping, or delayed engagement after fluid contamination, Transmission failure within days if coolant enters transmission
Fix: External cooler line failure: replace lines and flush system, 2-3 hours. Internal radiator leak is catastrophic — coolant destroys clutch packs. Requires radiator replacement, complete transmission flush or rebuild (12-16 hours), and often full 4T65-E replacement if contamination went unnoticed.
Estimated cost: $300-500 (lines only) or $2,800-4,200 (transmission rebuild/replacement after coolant contamination)
4T65-E Transmission Torque Converter Shudder and Failure
Common · medium severity
Typical onset: 80,000-150,000 mi
Symptoms: Vibration/shudder at 40-50 mph during light acceleration, Harsh 1-2 or 2-3 shifts, Whining noise from torque converter, Check engine light with converter clutch solenoid codes
Fix: Early stage: fluid and filter change with additive may help temporarily. Real fix is torque converter replacement requiring transmission removal, 10-12 hours labor. Often accompanied by worn 2nd gear band or clutch packs requiring full rebuild.
Estimated cost: $1,800-2,800
Power Steering Pressure Hose Leaks
Occasional · medium severity
Typical onset: 90,000-140,000 mi
Symptoms: Power steering fluid weeping or spraying from high-pressure line near pump, Groaning noise on cold starts, Heavy steering effort intermittently, Fluid spots under front of vehicle
Fix: Replace pressure hose assembly from pump to rack, 1.5-2 hours. These corrode and burst at crimp fittings. Don't ignore — pump runs dry quickly and destroys itself, tripling the cost.
Estimated cost: $250-400 (hose) or $650-900 (if pump damaged)
Rear Suspension Trailing Arm Bushing Deterioration
Occasional · medium severity
Typical onset: 80,000-120,000 mi
Symptoms: Clunking from rear over bumps, Rear end feels loose or unstable on highway, Uneven rear tire wear, Visible cracking/separation of rubber bushings on trailing arms
Fix: Replace trailing arm bushings or entire trailing arms (bushings aren't always sold separately). 3-4 hours per side, 6-7 hours for both. Alignment required after. NHTSA recall 07V329000 addressed some of this but not all vehicles or bushings covered.
Estimated cost: $600-1,000 (both sides)
Fuel Pump and Sender Assembly Failure
Occasional · medium severity
Typical onset: 100,000-160,000 mi
Symptoms: No-start or extended cranking, especially when tank below 1/4, Intermittent stalling at highway speed, Erratic fuel gauge reading or stuck gauge, Whining noise from fuel tank
Fix: Drop tank and replace fuel pump module assembly, 2.5-3.5 hours. Common on GM minivans of this era. Not expensive but labor-intensive with full tank.
Estimated cost: $450-700
EVAP Vent Valve Solenoid and Purge Valve Issues
Occasional · low severity
Typical onset: Any mileage
Symptoms: Check engine light with P0449, P0455, P0442 codes, Failed emissions test, Slight fuel smell near rear of vehicle, Hard fuel tank vacuum release when opening gas cap
Fix: Replace EVAP vent solenoid mounted near fuel tank (1 hour) or purge valve near engine (0.5 hour). Diagnose with smoke test if multiple codes present. Common nuisance, not dangerous.
Estimated cost: $200-350
Owner tips
Change Dexcool coolant every 50,000 miles religiously and inspect intake manifold gaskets annually after 60k — catching seepage early saves $5,000+
Drain-and-fill transmission fluid every 40,000 miles with AC Delco Dexron VI; the 4T65-E is marginal at best behind these engines
If buying used, pull dipstick and check for ANY milkiness in oil or strawberry-milkshake in coolant — both are instant walk-aways
Budget $1,500-2,000/year in deferred maintenance catching up on a higher-mileage example; these were not well-maintained by original owners
Hard pass unless under $3,000 with documented recent engine/transmission work — the dual catastrophic failure modes (intake gaskets and transmission cooler contamination) make this a financial trap for average DIY-ers.
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.
Fitment notes: Side terminal battery; standard for GM minivans of this generation
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Every control module on the 2005-2007 Buick Terraza — where it lives, replacement time, and what it takes to program a replacement. Modules marked dealer / factory tool won't work after a part swap alone — budget for programming.
Electronic Brake Control Module (EBCM)2.0 hr R&Rrelearn only +0.3 hr▸ programming details
📍 Engine compartment, driver side frame rail near master cylinder, integrated with ABS hydraulic unit
🔧 GM Tech 2
⚠️ Brake bleeding and automated bleed procedure required after replacement
Body Control Module (BCM)1.5 hr R&Rdealer / factory tool +1.0 hr▸ programming details
📍 Behind center instrument panel, above center console, accessible by removing radio trim
🔧 GM Tech 2 with TIS2000/SPS
⚠️ Controls lighting, door locks, remote start; VIN and option configuration required
📍 Under driver seat, mounted to seat frame (if equipped with memory seats)
🔧 GM Tech 2
⚠️ Optional equipment; memory positions must be reprogrammed by user
Transmission Control Module (TCM)no coding
📍 Integrated within PCM (4T65-E transmission)
⚠️ Not a separate module; transmission control integrated into PCM
Theft Deterrent Module (TDM)no coding
📍 Integrated within BCM
⚠️ PassLock II system; theft deterrent functions handled by BCM
Electronic Power Steering Control Module (PSMC)no coding
📍 Not equipped - hydraulic power steering only
⚠️ Terraza uses conventional hydraulic power steering; no electronic module
Aftermarket tool coverage varies by software version and vehicle build — treat "aftermarket tool" rows as "usually possible" and verify against your tool maker's coverage list before promising a customer. Spot a wrong location or hour? Tell us — corrections ship fast here.
THE BRAUN CORPORATION HAS NOTIFIED NHTSA ABOUT A DEFECT IN CERTAIN MODEL YEAR 2005-2008 GENERAL MOTORS MOBILITY CONVERSION, HANDICAPPED ACCESSIBLE LOW FLOOR MINIVANS. DURING CONVERSION, THE DRIVER OR PASSENGER SIDE TRAILING ARM MODIFICATION MAY NOT HAVE BEEN ADEQUATELY WELDED.
Consequence: A SQUEAKING OR CLUNKING NOISE MAY DEVELOP. THE TRAILING ARM BUSHINGS MAY PREMATURELY WEAR AND THE TRAILING ARM MAY FRACTURE OR SEPARATE, ALLOWING THE REAR AXLE TO BECOME PARTIALLY SEPARATED FROM THE CHASSIS INCREASING THE RISK OF A CRASH.
Remedy: DEALERS WILL INSPECT AND WILL HAVE A SUPPLY OF RETROFIT PARTS AVAILABLE TO REMEDY THE VEHICLES FREE OF CHARGE. THE SAFETY RECALL BEGAN ON JUNE 4, 2010. OWNERS MAY CONTACT BRAUN AT 1-800-488-0359.
STEERING · 09E005000
2009-02-17
DORMAN IS RECALLING 979 STEERING KNUCKLES, DORMAN P/NOS. 697-902 AND 697-903, SOLD UNDER DORMAN'S "OE SOLUTIONS<SUP>TM</SUP>" BRAND NAME, AND NAPA P/NOS. 7-8502 AND 7-8503 WHICH WERE SOLD FOR REPLACEMENT USE ON THE VARIOUS VEHICLES LISTED ABOVE. A POTENTIAL MATERIAL OR DESIGN DEFECT COULD RESULT IN THE STEERING KNUCKLE BREAKING IN THE HUB AREA.
Consequence: A BROKEN STEERING KNUCKLE COULD RESULT IN LOSS OF STEERING CONTROL AND A POSSIBLE CRASH WITHOUT WARNING.
Remedy: DORMAN WILL NOTIFY OWNERS AND REPLACE THE DEFECTIVE STEERING KNUCKLES FREE OF CHARGE AND REIMBURSE THE REPAIR FACILITY OR OWNER FOR LABOR. THE RECALL BEGAN ON FEBRUARY 23, 2009. OWNERS MAY CONTACT DORMAN'S TOLL-FREE HOTLINE AT 1-800-523-2492 AND PRESS 5.
Wiper blades
GMT200 platform minivan shared with Chevrolet Uplander, Pontiac Montana SV6, and Saturn Relay
Size-standard part numbers — verify your connector type before buying. Rear blades are model-specific; check the package's vehicle list.
Fuel economy figures are EPA data via fueleconomy.gov (median across matching trims). Performance figures are compiled estimates for the 2007 Buick Terraza 3.5L V6 and can vary by trim.
🔧 Database maintained under the daily editorial review of Chris Hackleman · Master Technician · 20+ years and Jeff Moore · Master Lexus & Toyota Mechanic · 20+ years.