Toyota 4Runner Problems

RepairPal has identified the most common problems with the Toyota 4Runner as reported by actual vehicle owners. We'll tell you what the problem is and what it'll take to fix it.

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Known Problems

The Throttle Position Sensor can get out of adjustment due to wear in the throttle body or due to carbon build up. This will cause the idle timing to advance more than 30 degrees which will cause very high HC and NOx emissions. Conversely, the Throttle Position Sensors can wear out and not properly advance the timing which causes a lack of power and poor fuel economy.

At higher mileages, (125,000-150,000) the automatic transmission may not shift correctly. This can be caused by the throttle position sensor being out of adjustment or a shift solenoid needing to be replaced. Typically the transmission does not need to be completely overhauled.

At 125,000-150,000 miles, the Master Cylinder may need replacing. It is critical to adjust the brake pedal to Master Cylinder pushrod clearance or the brakes will drag and over heat.

Vehicles equipped with rear passenger heating may have issues with the engine coolant lines that supply warm coolant to the rear heater.

These lines frequently leak, causing engine overheating and coolant dripping on or around the passenger side rear wheel.

To correct the leak, the hoses must be replaced.

To prevent the leak, the coolant should be flushed and replaced every 24-36 months.

The 1996-2002 Toyota 4Runner with the automatic transmission may develop an issue which is commonly known as the "strawberry milkshake".

The name is based on the color and consistency of the fluid found in the coolant reservoir, transmission, and radiator.

The radiator on these models has an isolated portion for cooling automatic transmission fluid(ATF) that is pumped in and out by the transmission. This area of the radiator is known to rupture internally, and the following occurs:

  • Transmission overheating warning light
  • Transmission slipping (engine revs high and vehicle moves slowly)
  • Engine overheating
  • ATF and engine coolant mix in the radiator, engine, and transmission

Engine coolant in the transmission can cause severe damage, and if not caught immediately may require replacement or rebuild of the automatic transmission.

To correct the situation, the radiator must be replaced, and the engine cooling system must be flushed thoroughly. Also, the transmission will need to be professionally flushed, inspected, and possibly repaired or replaced.

To prevent this from occurring, proactive replacement of the radiator is necessary and recommended.

Loud rattling or loud slapping may be heard from the engine on the 1996-2002 Toyota 4Runner with the 2.7L I4 engine. 

These noises has two known causes: a failed balance shaft bearing, and a failed timing chain tensioner. 

The balance shaft, also known as the counter rotating assembly, is installed to reduce engine vibration, and counter the rotational force of the crankshaft and camshafts. When the bearing fails, it will rattle loudly, and the timing chain will produce a metallic slapping noise. The rattle has been described as shaking a can of marbles. 

The timing chain tensioner is also known to fail, allowing the timing chain to contact the timing chain housing. This produces a metallic slapping noise coming from the front of the engine, but there is no "can of marbles" sound associated. This would not indicate balance shaft failure, but the timing chain may need to be replaced.  

To repair these issues inspection of the entire timing chain system will be necessary, and replacement of the timing chain, timing chain guides, balance shafts, timing chain tensioner, and associated seals may be necessary. 

Avoiding these issues may be possible by early oil changes, and using the factory specified engine oil. 

Drivers may hear a loud noise, much like a vacuum cleaner, coming from their engine on cold starts. This affects the 2005-2009 Toyota 4Runner V8 models. 

The noise is from the secondary air pump, which sends hot air to the catalytic converter when the engine is cold. This allows the catalytic converter to clean exhaust better, and lower emissions while the engine is warming up.

Pump failure may result in:

Fixing the issue involves removal of the intake manifold, and replacement of the secondary air pump.

The Toyota 4Runner with the 2.7L I4 engine has a known issue with the valves that if left unchecked, will cause burned valves and engine performance issues. 

The engine ‘breathes’ through valves that are pushed open by the camshaft, and closed by springs. When valves are closed, they seal against a valve seat. In this vehicle, the valve seat is too soft, so after the valve contacts it thousands of times, it becomes crushed. Once it is crushed, the valve can no longer make a proper seal, and the valves erode due to extreme temperature (burnt valve).

Symptoms related to this issue:

To repair the burnt valves, the cylinder head must be removed and rebuilt, which is a costly internal engine repair, however, this issue can be prevented through inspection and adjustment of valve clearances every 40,000 miles.

Owners frequently complain of leaking rear axle seals, which leaves gear oil on the inside of the rear tires and on the ground near the wheels.

The leaky seals allow gear oil to drip onto the rear brakes, and anti-lock brake (ABS) speed sensors causing poor braking and illumination of the ABS and Traction Control lights.

The correction is to replace the axle shaft seals, and clean all brake components in the rear of the vehicle. Replacement of wheel speed sensors has been necessary if the issue was unresolved for extended periods of time. 

The Toyota 4Runner may develop a condition with the HVAC ducting system causing noisy and faulty operation of the blend doors. The blend doors are actuated by the selector button, and change the direction of airflow to the selected location, i.e. vent, floor, defrost. 

The correction is to replace the blend doors.

Usually by 150,000 miles the AC system will need some attention, especially in climates where it is used often. Our technicians tell us that it is best to service the AC system every 2-3 years. This keeps the moisture in the system at a minimum which extends the life of the components.

The EGR System tends to get restricted or blocked with carbon after 100,000- 125,000 miles which will cause an emissions test failure for NOX. If the EGR system is equipped with an EGR temperature sensor it will trigger a Check Engine Light for improper EGR flow. The repair is to clean out the EGR passages and the EGR Temperature sensor. Our technicians tell this repair is pretty straight forward and takes about 1-1.5 hours. It is also wise to verify the EGR system components i.e. the Transducer, EGR Valve and VSV Solenoid at this time.

Front brake rotors can wear causing a pulsation felt in the brake pedal. Our technicians tell us this condition is best corrected by replacement of the front rotors and brake pads.

Toyota issued a recall on the lower ball joint due to the possibility of premature wear from improper finishing in production. The ball joints will be replaced under the recall. This recall applies to 2001-2002 models only. Please contact you local Toyota dealer to see if your vehicle is included.

The evaporative emission (EVAP) system may illuminate the vehicle's Check Engine Light due to intermittent failure of the charcoal canister purge control solenoid valve or canister failure. Upon failure of the charcoal canister, debris may circulate around the EVAP system causing other emission control problems.