Tappet Adjustment

A tappet adjustment is the process of re-setting the tolerances between the lifter and the valve stem.

Every car has a different clearance that the Technician should adjust it to. We use a system called autodata to retrieve the recommended tolerances from the manufacturer. We print this information for our Technicians to follow.

The most common vehicles we perform these on are Mitsubishi’s Tritons and Isuzu D-Max.

The tappet and solid lifter mechanism is not found in all diesel engines, the other type is referred to as hydraulic. Most German cars use the hydraulic type.

Process for JDM P/L to perform a tappet adjustment

We perform this service at our workshop in Charmhaven, 2263. Please call us or book online.

This service takes approximately 6-8 hours.

We can usually perform this service in a single business day, providing the car is delivered to us nice and early!

Symptoms a car required a tappet adjustment

When there is too much valve clearance, the engine will misfire and rattle.

When there’s too little valve clearance, the engine will also misfire, due to the valve remaining slightly open & allowing the loss of compression. This will also result in a buildup of carbon.

Cars requiring an adjustment may exhibit the following problems

  • Difficult to start
  • Lack of power
  • Idle poorly
  • Exhibit carbon buildup problems such as a blocked EGR valve
  • Blowing excessive smoke

This is a fairly advanced problem and the adjustment itself is a difficult task. This is why most people have their local Mechanical workshop perform the adjustment.

How often do tappets require adjusting?

We would estimate that most modern vehicles require tappet adjustments between every 30,000 – 60,000kms. All vehicle manufacturers state when the required time or kilometres that the adjustment is due.

What does adjusting the tappet achieve?

The goal of this service is to have the intake valve and the exhaust system open at the exact time they’re designed to.

When the tolerances are set back to where they should be, the engine will be running much better and offer higher performance than before. All the symptoms listed above will be resolved.

The engine will also operate more efficiently. Having the tappet adjusted as per the manufacturer’s recommendations will also prevent more costly repairs down the road.