Overheat alarm but not overheating!
Printed From: myHanse.com
Category: Hints & Tips
Forum Name: 415/418
Forum Description: 415/418 Hints, Tips and News
URL: https://www.myhanse.com/forum_posts.asp?TID=9452
Printed Date: 27 March 2026 at 03:40
Software Version: Web Wiz Forums 12.06 - https://www.webwizforums.com
Topic: Overheat alarm but not overheating!
Posted By: High Time
Subject: Overheat alarm but not overheating!
Date Posted: 12 February 2016 at 16:48
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This is a curious one that currently has me scratching my head. Although posted on the 415 panel I believe the engine instrumentation is the same on all the current D2 engines. My D2-40 overheating alarm is triggering when the temperature at the sensor is only 85C (checked with a cheap IR thermometer but feels about right). Also water flow (seawater and coolant) is OK. My first thought was a faulty sensor but this appears to match the resistance curve given in the MDI testing manual (snippit attached below; you don't need a breakout box - just remove the wire and measure to earth) so I now suspect the voltage that is used in the sensing circuit (nominal 5V open circuit but falls as the sensor resistance falls), or the alarm trigger circuit. When the alarm triggers I get the following readings at the sensor Sensor resistance 65 ohms Sensor temperature 83C (as measured with the IR thermometer and correlates with the resistance) Sensor voltage 0.62V. My questions -
Any other thoughts gratefully received. Although I'm sure the engine is not overheating I don't like disabling the alarm so need to fix this. Thanks Roger PS The engine control panel is the simple one - alarms are indicated in the tacho window; no gauges.  ------------- Roger High Time (415 #038) |