whitecrystal1
Seaman
- Joined
- Aug 5, 2007
- Messages
- 51
My father-in-Law has a 1990 Regal with a Merc. 5.7/Alpha 1 Gen 1 (just over 600 hours fresh water use only) we have been trying to find out why it overheats at idle but not when you increase the RPM's above 1K or while underway. The thermostat, impeller and exhaust flappers were replaced at the end of last season.
Searching the forums I learned about the springs and plastic balls in the thermostat housing so I removed it from the boat and cleaned up the housing all ports and stretched the springs some but that was not our issue as we found it was still overheating. Next we pulled the exhaust elbows to take a look inside to see if they were clogged up and they were not. Scratching our heads and not sure what else to check, we pulled the lower unit off the drive to re-inspect the impeller to make sure no fines broke off incase we did something wrong when we replaced it last season, we found we spun the impeller in backwords :facepalm:
I've read post from other's stating that it does not matter which way you install the impeller because it will spin the fins around if installed backwards... this is not true, and if other's follow those stating this they may have a similar problem we just went through.
Searching the forums I learned about the springs and plastic balls in the thermostat housing so I removed it from the boat and cleaned up the housing all ports and stretched the springs some but that was not our issue as we found it was still overheating. Next we pulled the exhaust elbows to take a look inside to see if they were clogged up and they were not. Scratching our heads and not sure what else to check, we pulled the lower unit off the drive to re-inspect the impeller to make sure no fines broke off incase we did something wrong when we replaced it last season, we found we spun the impeller in backwords :facepalm:
I've read post from other's stating that it does not matter which way you install the impeller because it will spin the fins around if installed backwards... this is not true, and if other's follow those stating this they may have a similar problem we just went through.