Perkins — To test and to inspect the thermostat
Testing & diagnosis
From a Perkins service manual covering: 403C-11, 403C-15, 404C-22. Check it applies to your exact model before use.
Applies to: Perkins 403C-11, Perkins 403C-15, Perkins 404C-22
Procedure
- Put the thermostat into the water.
- Raise the temperature of the water gradually.
- Record the valve opening temperature and the valve lift.
Specs & values
- 403C-11 eBay $31.20 FridayParts $10.50 SinoCMP $51.00: starts to open at 75 °C, fully open at 87 °C. 403C-15 eBay $66.49 FridayParts $9.90 SinoCMP $139.00/404C-22 eBay $699.00 FridayParts $9.90 SinoCMP $369.00: 80 to 84 °C / 95 °C. 404C-22T FridayParts $15.00 SinoCMP $289.00: 71 °C / 82 °C.
- The start to open temperature is stamped on the thermostat.
- 3 to 5 minutes will be required before the valve starts to operate.
Full service-parts list: Perkins 403C-11 →, Perkins 403C-15 →, Perkins 404C-22 →
Source: Perkins 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.