Turbocharger - Misdiagnosis/Diagnostic Procedure
86ford23 Article No. 86-3-16TURBOCHARGER (2.4L DIESEL) - MISDIAGNOSIS OR REPLACEMENT FOR CONDITION OF OIL WEEPAGE AT THE INTAKE CROSSOVER TUBE SEALS - DIAGNOSTIC CHECK PROCEDURE
LINCOLN-MERCURY 1984 CONTINENTAL, MARK VII
This article is being reissued to clarify check-out procedures that must be followed before any turbochargers are replaced.
Figure 15:
Some turbochargers are being replaced due to misdiagnosis of an oil weepage condition at the intake crossover tube sealing sleeves (Figure 15).
This weepage condition may be caused by loose or mispositioned crossover tube sleeves or clamps, loose vacuum hoses, kinked or pinched vapor separator drain hose, a restriction in the vapor separator, excessive
Figure 16:
crankcase pressure or a turbocharger seal leak. A turbocharger that may be suspect for oil leakage past the seals will have worn bearings and will not cause a deposit of oil at the intake housing of the turbocharger or inside the air intake bellows located at the air cleaner housing (Figure 16). A film of oil may be evident on the walls of the bellows or at the intake side of the turbo housing. This is normal due to the PCV return vent system being attached to the air cleaner and does not mean that the turbocharger seals are leaking.
The following provides a diagnostic procedure for condition of oil weepage at the intake crossover tube sleeves:
1. Verify oil weepage at the intake crossover tube rubber sleeves.
2. Remove the rubber sleeves from the crossover tube and clean with solvent. The sleeves should be replaced if found deformed due to improper install - ation.
3. Use solvent to clean the crossover tube and the sealing surfaces at the intake manifold and turbocharger. Reinstall the tube, sleeves and tighten clamps tight.
Figure 16:
4. Loosen the hose clamp at the air intake bellows (Figure 16) and slide the bellows off the air cleaner housing. Using a suitable light, look into the bellows and observe the compressor wheel of the turbocharger. A film of oil may be evident on walls of the bellows and at the turbocharger housing. This is normal and does not mean that the turbocharger oil seal is leaking.
If a puddle of oil is evident inside the bellows, it indicates oil passing through the vapor separator. Clean the oil from inside the bellows with solvent.
Loose or open vacuum hoses will cause excessive air flow through the vacuum pump into the crankcase permitting oil to pass through the vapor separator. Verify that all engine vacuum hoses are connected and tight.
If the wall of the bellows and the turbocharger housing are dry of oil, refer to Section 24-45-1 of the 1985 Car Shop Manual, Volume D to remove the turbocharger from the engine and check axial and radial clearances of the shaft bearings. Turbochargers will have worn bearings if oil leakage is suspect past the shaft seals.
Figure 17:
5. Visually inspect the small drain hose connecting from the bottom of the vapor separator to the oil pan (Figure 17) for being pinched or kinked due to it possibly being misrouted between the cylinder block and the starter. If found misrouted, remove the drain hose and reinstall the hose to the outboard side of the starter. Any restriction in the oil drain system must be corrected or oil can enter the air intake system.
6. Remove the vapor separator from the rocker cover. Insert a 7/32 inch drill bit into the hole located at the bottom end of the separator. The drill bit should slide freely into the hole at least 1-1/2 inches. If the drill bit does not fit freely, it indicates a restriction and the vapor separator should be replaced. If no restriction is evident, clean the separator with solvent and reinstall.
7. If above procedure does not identify the cause for this concern, perform an engine crankcase pressure diagnostic check published in TSB 85-6-6 dated March 21, 1985. Crankcase pressure is checked at the oil fill hole in the valve cover using the oil cap adapter and 0-60 inch water magnehilic gauge from Rotunda model 019-00022 or equivalent. The maximum allowable pressure is 30 inches water at 3300 rpm. A reading exceeding this indicates cylinder leakage past the piston rings.
OTHER APPLICABLE ARTICLES: Supersedes 85-11-8
WARRANTY STATUS: "INFORMATION ONLY"