Cooling System - Coolant Loss/Leakage/Lamp On/or Odor
File In Section: 6 - EngineBulletin No.: 67-62-04
Date: December, 1996
Subject:
Coolant Loss, Visible Coolant Leakage, Low Coolant Lamp On, or Coolant Odor, Caused by Coolant Leakage (Install a New Thermostat Gasket)
Models:
1996-97 Buick Skylark
1996-97 Chevrolet Cavalier
1997 Chevrolet Malibu
1996-97 Oldsmobile Achieva
1996-97 Pontiac Sunfire, Grand Am
with 2.2L, 2.4L Engines (VINs 4, T - RPOs LN2, LD9)
Built before October, 1996
Condition
Some customers may comment about engine coolant loss, low coolant lamp on, visible coolant, or a coolant odor from the engine compartment. Some owners may be unable to distinguish the coolant from transmission fluid due to its orange color.
Cause
Some 1996 and 1997 J and N model cars equipped with 2.4 Liter (VIN Engine Code T RPO LD9) engines may exhibit coolant leakage at the joint where the radiator outlet pipe is connected to the coolant pump cover. In addition, some of these vehicles may exhibit leakage at the joint between the cooling system air bleed pipe and the coolant outlet. On 2.2 Liter engines (VIN Engine Code 4 - RPO LN2) coolant leakage may occur between the thermostat housing and the coolant inlet pipe.
Correction
On vehicles exhibiting leakage at the thermostat gasket joint, install a new thermostat gasket with part number 24576633, using procedures outlined in the Engine Cooling Section on the Service Manual.
1. If any of the previously noted conditions occur, first inspect the vehicle per the Engine Cooling Section of the applicable Service Manual. If no other cause is found for the condition, proceed with step 2.
2. Inspect the joint between the radiator outlet pipe (thermostat housing on 2.2L engines) and the coolant pump cover (coolant inlet pipe on 2.2L engines) for signs of leakage. Pressure or dye testing may be necessary in some instances.
3. If any signs of coolant leakage are noted, replace the thermostat gasket using the procedures in the Engine Cooling Section of the Service Manual.
4. If the thermostat seal has been replaced with part number 24576633 and there continues to be leakage between the radiator outlet pipe (thermostat housing on 2.2L engines) and the coolant pump cover (coolant inlet pipe on 2.2L engines), replace the thermostat housing on 2.2L engines or the radiator outlet pipe on 2.4L engines.
Important:
Do not attempt to install any seal other than 24576633 into this joint! If an attempt is made to install a thicker seal, the flange on the radiator outlet pipe will be distorted when it is tightened creating an additional leak. If any attempt has been made to repair the leak with a thicker seal, the thermostat housing on 2.2L (RPO LN2) engines or the radiator outlet pipe on 2.4L (RPO LD9) engines should be replaced to prevent leaks caused by distortion.
Important:
DO NOT REPLACE 82°C (180°F) 1996 THERMOSTAT WITH ANY OTHER THERMOSTAT. If poor heater performance is noted, follow diagnostic procedures in Section 1A of the appropriate Service Manual.
In some instances of poor heater performance, 1995 91°C (195°F) thermostats have been installed in 1996 2.2L LN2 and 2.4L LD9 engines. The 1996 thermostat used for the inlet thermostat system is unique and cannot be replaced with a thermostat from an outlet side thermostat application.
If a 1995 91°C (195°F) thermostat is used to replace a 1996 82°C (180°F) thermostat, the following conditions WILL occur:
^ 91°C (195°F) (1995) vs. 82°C (180°F) (1996) will cause the 1996 2.2L LN2 and 2.4L LD9 engines to run hotter at low RPM.
^ A lighter spring in the 91°C (195°F) (1995) thermostat will allow the thermostat to be pulled open by coolant flow at higher RPM, causing the engine to run too cold and will cause poor heater performance at highway speeds.
5. On vehicles equipped with the 2.4 Liter (VIN Engine Code T RPO LD9) engine, inspect the sealing of the joint between the coolant outlet and the cooling system air bleed pipe.
If any leakage is noted, replace the coolant outlet, GM P/N 24575259, air bleed pipe, GM P/N 24574205, and "0" ring seal, GM P/N 24573057. Use silicone based lubricant, GM P/N 12345579, when installing the new air bleed pipe and seal into the coolant outlet.
Parts Information
Whenever ordering parts, refer to the part numbers as shown.
Warranty Information
For vehicles repaired under warranty, use: as shown.