Temperature Issue on Universal M30 Diesel Motor

[pvisich]

This past weekend my temperature gauge spiked suddenly and the alarm went off but the motor seemed to be running fine. I turned off the motor and sailed back to the marina. I turned on the motor to get in my slip and the temperature looked fine, then suddenly jumped again. Motor is circulating water fine, strain basket is clean, and impeller looks good. It was suggested to me that this may be more of a electrical issue due to the sudden spike in the temperature gauge and to check the connection of the wire that attaches to the motor that comes from the temperature gauge. Anyone have a suggestion on where and what color I would find this wire on a Universal M30 diesel motor on my CD 330 (1986)? I am hoping the wire is loose and the cause of the problem and nothing more serious, fingers crossed. Thanks, Paul

[Jim Walsh]

You didn’t mention your thermostat. You can remove it and check that it works in a pan of water brought to a boil but if you haven’t changed it recently I’d just replace it. They don’t often fail catastrophically, they usually fail by operating intermittently before complete failure.
Your owners manual will have a wiring diagram so you can trace the sensors connection.

The service manual can be found on this site
http://capedory.org/cdsoalook-groupsNpubs.html

[pvisich]

Thanks Jim for your reply. After adding approximately a quart of coolant the motor ran fine with the temp gauge staying right around 160 degrees, but would agree in your suggestion to replace the thermostat. Thanks!