Kohler — Dual Gauge Cylinder Leakdown Test
Testing & diagnosis · Cylinder / piston rings / valves
From a Kohler service manual covering: KT600, KT610, KT620, KT715, KT720, KT722, KT724, KT725, KT726, KT730, KT735, KT740…. Check it applies to your exact model before use.
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Before you start
- Carbon monoxide can cause severe nausea, fainting or death
Procedure
- Run engine until oil temperature reaches and maintains 150°F (66°C) or more for a minimum of 5 minutes under normal load
- Remove spark plug(s) and air filter from engine
- Rotate crankshaft until piston of cylinder being tested is at TDC of compression stroke; hold engine in this position with holding tool
- Connect an air source (at least 100 PSI) to tool
- Turn regulator knob counterclockwise; confirm both gauges read approximately the same pressure from 0 to 80 PSI; release pressure fully before proceeding
- Install adapter hose into spark plug hole of cylinder being tested (use 12mm x 14mm adapter if required)
- Firmly hold engine at TDC; connect adapter hose to tool quick connect; turn regulator knob clockwise until left gauge reads 20 PSI
- Slowly turn regulator knob clockwise until left hand gauge maintains selected test pressure (80 PSI for engines over 200cc, 35 PSI for single cylinder push mower applications)
- Compare right gauge reading to Test Pressure Chart to identify percentage of leakage
- For engines exhibiting leakage in yellow or red zone, repeat test procedure after operating engine under normal load conditions
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Green zone = good; Yellow zone = some wear; Red zone = excess wear, disassembly required
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.