Some of the history of the boat and motor.
This thread maybe skip toward the end.
http://www.wellcraftv20.com/communit...ighlight=specs
Changing the t-stats and sensors.
http://www.wellcraftv20.com/communit...ead.php?t=7633
And the bad part.
http://www.wellcraftv20.com/communit...ad.php?t=11817
See if the pictures help.
Till I got it, it was most likely a freshwater engine and I doubt I've put 20 hours on it.