Hello All,<br />I'm changing the impeller on my 1990 40HP Merc Classic. Do I need the water pump kit for $80 or just impeller for around $20. Tell tale is working fine but alarm is going off after about 15 min of being underway. Motor sat for a couple years before I bought it. Cant find a thermostat listed on Merc parts express. Does my motor have one? Haven't gotten repair manual yet. Can anyone help?<br />Thanks,<br />Bruce