Engine Mount Vacuum System Leak Test
The engine mount vacuum system leak test should only be performed if there is strong evidence of an improper functioning vacuum operated engine mount system or a leak.
All other diagnostics checks should be performed before completing the engine mount vacuum system leak test. Refer to the following:
The total engine mount vacuum system must be replaced if glycol fluid is found anywhere in the system. Glycol fluid will damage system components and cause them to fail.
Do not use pressure to test the engine mount vacuum system or component damage may occur.
If relying on stored vacuum in the engine mount system vacuum for testing, start the vehicle and allow vacuum to build up to operating vacuum pressure prior to and during testing.
Vacuum leaks may be found using the J-23738-A Mityvac. Using the below chart, apply vacuum to each component of the engine mount vacuum system. The vacuum valve electrical connectors are part of the vacuum system and serve as partial seal against vacuum leaks. When performing the vacuum leak check procedures below, make sure the electrical connections to both vacuum valve assemblies remain intact. It will be necessary to use the GDS2- MDI to command the valve assemblies on to complete the test of the entire system and valve (solenoid) assemblies.
Before checking for vacuum leaks, perform the Valve Assembly Functional Test and a visual inspection of the engine mount vacuum system checking for loose connections. If the engine mount vacuum system is found to be within specification, it is not necessary to check the individual components.
Care should be taken when disconnecting and reconnecting the vacuum hoses as not to damage the internal hose connection. Before reconnecting any vacuum hose, inspect the female connector for damage. If significant damage is found as to affect the sealing, replace the affected hose. Refer to Engine Mount Vacuum Hose Replacement .
| Component | Mityvac Connection | Valve Assembly Position (GDS2-MDI) | Apply Vacuum | Acceptable Range (after 30 seconds) |
|---|---|---|---|---|
| Entire System | At check valve | ON | 70 kPa (10 psi) | 70 - 65 kPa (10 - 9.5 psi) |
| LH Engine Mount | At vacuum port 2 (smaller opening | OFF | 70 kPa (10 psi) | 70 - 65 kPa (10 - 9.5 psi) |
| At vacuum port 1 (larger opening) | OFF | 70 kPa (10 psi) | 70 - 65 kPa (10 - 9.5 psi) | |
| RH Engine Mount | At vacuum port 2 smaller opening | OFF | 70 kPa (10 psi) | 70 - 65 kPa (10 - 9.5 psi) |
| At vacuum port 1 (larger opening) | OFF | 70 kPa (10 psi) | 70 - 65 kPa (10 - 9.5 psi) | |
| Tank | At either tank port, plug the other | OFF | 35 kPa (5 psi) | 35 - 30 kPa (5 - 4.5 psi) |
| Engine Mount Solenoid Valve- Right | At inlet port, plug port going to engine mount | ON | 70 kPa (10 psi) | 70 - 65 kPa (10 - 9.5 psi) |
| Engine Mount Solenoid Valve- Left | At inlet port, plug port going to engine mount | ON | 70 kPa (10 psi) | 70 - 65 kPa (10 - 9.5 psi) |
If the engine mount vacuum system is found to be out of specification and the individual components are within specification, perform a detailed inspection of the engine mount vacuum system hose assembly. Inspect for any of the conditions below:
- Loose connection at each of the mounts, solenoids, or check valve
- Pinched vacuum lines
- Contamination in the vacuum lines, tank, or valve assemblies
- Cracks, cuts, dry-rot
- Worn or damaged connectors
Repair or replace the engine mount vacuum hose assembly as necessary.