Turbocharger - Overboost Warning Comes On
Article No. 85-17-2TURBOCHARGER OVERBOOST WARNING COMES ON - TURBO WASTEGATE STICKING - 2.3L EFI TURBO
FORD 1985 THUNDERBIRD, MUSTANG SVO
LINCOLN-MERCURY 1985 COUGAR XR7
MERKUR 1985 XR4Ti
Some vehicles may develop a condition where the overboost light comes on and the overboost buzzer sounds on acceleration. The activation of the overboost warning system could be caused by the turbo wastegate sticking shut, resulting in an overboost condition of up to 24 psi. (Boost gauge may also show actual lbs. of boost.) This condition can be checked and repaired by using the following procedure.
IMPORTANT NOTE: Suspect turbochargers were built prior to the serial number 3827. Turbos built after serial number 3828 should be o.k. (Serial No. located on metal tag which is similar to carburetor I.D. tag.)
Figure 1 - Turbocharge Overboost - Repair Procedure:
1. Raise the vehicle and install a clutch housing alignment adapter (T75L-4201-A) fastened to a dial indicator with magnetic base (D78P-4201-B) at the end of the actuator and set the gauge to zero. (See Figure 1)
2. Connect a gauged air pressure line to the actuator inlet port. To get a gauged air pressure, use a combination air pressure regulator and air pressure dial (T79P-6634-A), connected to a source line (shop air supply).
3. Starting with zero air pressure, slowly increase the air pressure until the actuator arm moves about 0.38 mm (0.015 inch). The pressure gauge should read between 32-35 kPa (9.5 and 10.5 psi).
4. If the reading is not within specification, or if no movement is measured at 10.5 psi, replace the turbocharger assembly.
OTHER APPLICABLE ARTICLES: None
WARRANTY STATUS: Reimbursable within the provisions of the Warranty and Policy Manual.
OPERATION: SP9438A85
TIME: 1.7 Hrs. DLR. CODING: Basic Part No. 9G438 - Code: 41