TURBINE WHEEL/HOUSING CHECKS

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.

2. TURBINE WHEEL AND TURBINE HOUSING CHECKS

Remove the ducting from the turbine outlet. Using an inspection light:

Inspect the turbine for evidence of foreign object damage. This is usually not easily visible from the turbine outlet unless the damage is severe. Determine the source of the object and check for possible engine damage. Figure 20 highlights where turbine wheel rub frequently occurs.

Turn the rotating assembly by hand and feel for dragging or binding; also check by pushing the assembly sideways while turning. The wheel should turn freely and without any rubbing or scraping noises. If there are obvious signs of wheel nib or that the turbine housing has been operated at excessive temperatures, then the turbocharger is damaged and must be replaced. If you are still not sure whether the wheel is rubbing, inspect the bearing clearances after completing this section.

Look for evidence of oil leakage. If oil deposits are found, then determine whether the oil is from the engine or from the turbocharger center housing. Some oil residues may be cleaned; heavy oil residues may require replacement. If the oil is from the center housing, then remove the oil drain line and look into the turbocharger drain opening and drain line with an inspection light. Check for an oily, sludge build-up on the shaft between the bearing journals, in the drain cavity, and in the drain line.

Check the following to determine the cause of the problem and effect corrections as necessary:

a. Restricted draining or high crankcase pressure can raise the pressure of the center housing drain area above the pressure in the turbine housing forcing oil in that direction.

b. PCV flow control valves on spark ignition engines must operate as one way check valves when boost is developed. This reverses the direction of flow in the ventilation system. A partially closed PCV allows manifold boost to pressurize the crankcase.

c. Damaged oil drain line.

d. Improper line routing (more than 35 degrees from vertical or any sharp bends) or routings close to exhaust manifolds.

e. Submerged drain line from too high an oil level or equipment operated at extreme angle.

Correct any installation problems after completing the rest of this procedure. If turbocharger parts are damaged, the unit should be replaced at this time and corrective actions taken to prevent reoccurrence.

Refer to the engine manufacturer's service instructions for inspection requirements and replacement specifications.