Need for thermostat

[Rob Hoeflein]

Last fall we had a blockage in our exhaust. In troubleshooting the problem we found there was no thermostat in the engine. We have owned the 79 Catalina for 6 years and never noticed a problem with the temp., other then being slightly cool. I think the thermostat may have been missing for at least 10 years. Should I install one , or just leave well enough alone . Will the proformance improve ? We sail in the upper Chesapeake / Chester River Area April to Oct. water temp. is pretty warm . Thanks in advance for any info.
Rob

[Don Moyer]

Rob,

The danger in operating without a thermostat in a late model engine is that you have no protection against extremely high temperature spikes, in the event that a blockage occurs that would prevent water from entering the block through the "T" fitting in the water jacket side plate.

One of the functions of the (double acting) thermostat in a late model engine is to totally block the bypass loop at 180 degrees and direct all incoming water through the "T" fitting.

A new 140 degree thermostat should settle in around 160 to 170 degrees in your part of the Bay for most of the year, which should provide good performance for you in terms of fuel economy and clean spark plugs.

Best regards,

Don Moyer