Kohler ECV940 / ECV980 — Cylinder Leakdown Test (Dual Gauge)
Testing & diagnosis · Combustion chamber / valves / rings
For the Kohler ECV940 / ECV980, from the Kohler service manual.
Applies to: Kohler ECV940, Kohler ECV980
Before you start
- To prevent damage to gauge assembly, always turn pressure regulator knob to zero after each test.
Procedure
- Run engine until oil temperature reaches and maintains 150°F (66°C) or more for minimum 5 minutes under normal load.
- Remove spark plug(s) and air filter.
- Rotate crankshaft until piston is at TDC of compression stroke; hold engine in position.
- Connect air source (at least 100 PSI) to tool.
- Turn regulator clockwise; confirm both gauges read approximately same air pressure 0 to 80 PSI; release pressure.
- Install adapter hose into spark plug hole of cylinder being tested.
- Firmly hold engine at TDC; connect adapter hose to tool quick connect; turn regulator clockwise until left gauge reads 20 PSI.
- Slowly turn regulator clockwise until left gauge maintains selected test pressure; compare right gauge to Test Pressure Chart.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Left Gauge Regulated Pressure 80 PSI (engines over 200 cc)
- Left Gauge Regulated Pressure 35 PSI (single cylinder walk-behind push mower)
Source: Kohler 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.