Dashpot Control System

Engine must be at normal operating temperature. Check idle speed and adjust if necessary. Remove cap, filter and separator from dashpot. See Fig 1.
Start engine. Maintain engine speed at specified testing RPM. See DASHPOT TESTING RPM table. Plug Vacuum Transmitting Valve (VTV) hole with your finger. See Fig 1.
Release throttle. Dashpot should be extended and dashpot setting RPM should be as specified. See DASHPOT TESTING RPM table. If idle speed is incorrect, adjust dashpot. See Fig 2.
To check VTV operation, run engine at dashpot testing RPM for a few seconds. Plug the VTV hole with your finger. Release throttle. Uncover plugged hole. Engine should return to idle in about one second.
Install dashpot separator, filter and cap. Install filter with coarser surface facing outward.

DASHPOT TESTING RPM

Model

Testing RPM

⁽¹⁾ Dashpot Setting RPM

4A-FE

3500

2WD, 1500

4WD M/T, 1800

4WD A/T, 2200

4A-GE

2500

1800

⁽¹⁾	With cooling fan off.

Fig 1: Exploded View of Dashpot

Fig 2: Adjusting Dashpot Idle Speed