Re: Mercury 7.5 thermostat
Here is what my Clymers manual has to say.<br /> Although thermostats are no longer installed in Merc 7.5 and 9.8 outboards with the follwing serial numbers, the design has not been changed. A thermostat may thus be used as an accessory to maintain a constant,higher engine operating temperature. Merc recomends the installation of a t-stat in such engines when used primarily in cold water areas or where day to day temperture variations of 20-40 degs. f. are encounterd.<br /> U.S. ser# 5811769 and above did not have t-stat installed. Your ser# is 5616819. Most guys recomend running a t-stat. If a motor (any motor) orignaly had one installed I'll replace them. How ever I don't remember ever owning a Merc that has one. I tend to feel t-stats are a good idea. Just my opinion. My memory is short sometimes also.
