WASTEGATE ASSEMBLY CHECK

CAUTION: Do not run the engine during these procedures. If the engine has been running, make sure it is cool before beginning.

Warning! Operating the turbocharger without the inlet duct and air filter connected can result in personal injury. Equipment damage may result from foreign objects entering the turbocharger.

6. WASTEGATE ASSEMBLY CHECK

Wastegates may be an integral part of the turbine housing or a separate device plumbed into the exhaust system. Actuator's are connected directly to the compressor outlet or work in conjunction with the engine management system. Engine manufacturers supply specific information on wastegates because of their arrangement within the engine management system.

Actuators spring pre-load may be high enough to make checking for free movement by hand difficult or impossible. Visually check for obstacles that can prevent movement or closure. Inverted exhaust pipe connection studs can prevent some wastegates from opening. Stress relief cracking may be found around the relief port in turbine housings. Cracks that do not extend beyond the wastegate valve do not present a problem.

CAUTION! When checking an actuator do not over-pressurize because the diaphragm may become damaged. Swing valve actuators should move smoothly and show no decay when subjected to calibration pressures.

Many poppet valve units have a hollow stem that opens in the guide giving a small leak when pressurized. Poppet valve units also depend to some degree on engine vibration to overcome static friction. When checking this type unit, light tapping of the housing will usually provide an accurate calibration check.

Original equipment specifications for calibration should be closely followed because they are established to interact with the entire engine management system. The calibration pressure is not necessarily a reflection of expected manifold boost because other pressures act on the valve. In many cases pressure to the actuator is overridden by the engine control system to vary the amount of boost depending upon conditions.

Many actuators are mounted on a bracket away from high temperatures. Problems may come from bending of the brackets or rods. High temperatures from exhaust leaks, corrosion, or other loose or damaged components can also result in wastegate problems.