Thermal Valve - BRP Johnson J30TEL4SUA 2007 Service Manual

POWER TRIM AND TILT
OPERATION

Thermal Valve

The PTT system incorporates a thermal valve for protection of the internal components if excessive
downward force is exerted on the lower unit with the motor in a tilted position or, in the case of an impact
in reverse gear, the stern clamp/swivel brackets and the transom.
Should the propeller strike an underwater object while in reverse gear, a build up of pressure will be
induced in the lower cylinder chamber and the brackets and/or the transom may sustain damage. To pre-
vent this, the thermal valve will open to relieve the oil pressure, thereby softening the impact.
Internal PTT circuits are protected, as the thermal valve will open to reduce oil pressure caused by either
hot climate or abnormally heavy usage.
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