Generac — Cylinder Leak Down Test
Testing & diagnosis · Engine cylinders
From a Generac service manual covering: QUIETPACT 55, QuietPact 65, QuietPact 75. Check it applies to your exact model before use.
Applies to: Generac QUIETPACT 55, Generac QuietPact 65, Generac QuietPact 75, Generac GTV-760 engine
Procedure
- Remove a spark plug and remove the valve cover.
- Rotate crankshaft until piston reaches top dead center; both valves closed.
- Lock flywheel at top dead center.
- Attach leak down tester adapter to spark plug hole.
- Connect air source of at least 90 psi and adjust regulated pressure to 80 psi.
- Read cylinder pressure; 20 percent leakage is normally acceptable.
- Listen for air escaping at carburetor, exhaust and crankcase breather.
- Repeat on the remaining cylinder.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Air source at least 90 psi
- Regulated pressure 80 psi
- 20 percent leakage normally acceptable
Full service-parts list: Generac QUIETPACT 55 →, Generac QuietPact 65 →, Generac QuietPact 75 →
Source: Generac service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.