1998 Toyota T100 Problems

RepairPal has identified the most common problems with the 1998 Toyota T100 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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20
Known Problems

The 2.7L engine used in the 1994-1998 Toyota T100 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.

At 125,000-150,000 miles, the Brake 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.

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 (125,00+) the Engine Coolant Temperature Sensor may intermittently stop working, especially when the vehicle is fully warmed up. This can result in illumination of the Check Engine Light and/or an engine stalling problem.

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.

At higher mileages, an anti-lock brake system wheel speed sensor may wear out and illuminate the ABS warning light. It is recommended to replace the sensor with a factory part and be sure to clean all rust and debris from the mounting area because the mounting distance is critical. Failure to do so may result in the new sensor setting false trouble codes. Be sure to check the condition and runout of the front wheel bearings on the 2WD and 4WD vehicles and the CV joints on the 4WD vehicles since worn wheel bearings and/or CV joints can cause the ABS trigger rings to rub against the ABS sensors and damage them.

If the engine will not crank over, the most common problem is the starter. These will tend to go out at about 100,00-125,000 miles. Sometimes it is only the starter solenoid, but often the complete starter (including solenoid) needs to be replaced.

Occasionally, the mass air flow sensor can go lean and set a code P0170 for fuel system lean. This in not an oxygen sensor problem. If there are no vacuum leaks, the mass air flow sensor may need to be replaced. Our technicians remind us to use a factory part because the aftermarket rebuilds are very inconsistent.

A rough idle and even an emissions inspection failure for high HC and CO can be caused by improperly adjusted valves. Also, exhaust valves may become to tight which can lead to valve failures. Our technicians tell us that regular valve adjustment inspections are a must.

We recommend flushing the brake fluid every 60,000 miles because the fluid can become dirty and may cause problems in the brake system such as premature failure of the master cylinder or wheel cylinders.

Over the time the exhaust gas recirculation (EGR) system may become plugged with debris, the oxygen sensor may also be getting slow or 'lazy' around this time. When servicing or cleaning  the EGR system, it is a good idea to replace the oxygen sensor because it works in tandem with the EGR system.

In some vehicles, the automatic transmission over heat light may come with sustained highway driving or driving at a sustained speed. Flushing the transmission and changing from Dextron lll to Dextron ll can help remedy this problem.

Some engines have had the problem of the crankshaft pulley bolt coming loose. This will make a rattling noise as the engine idles. Our technicians tell us that the pulley bolt should have a thread locker applied and then retorqued.

At higher mileages (125,000+) the mass air flow sensor may cause the vehicle to idle rough, run rich and even stall. Our technicians recommended to replace the Mass Air Flow Sensor with a factory unit because the aftermarket units have very mixed results.

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.