89 Mercruiser 4.3 Thunderbolt Temp Gage Not reading

89Chaparral

Recruit
Joined
Jun 8, 2011
Messages
2
Hi Guys, great fourm. Not new to boating but a little new to computers. I have an issue I am trying to figure out. First of all my Temp gage is not reading. I discovered a tan colored wire with a blue stripe coming from sending unit (I think its sending unit) that has a round connector that obviously has to hook into a screw of some sort just hanging. It is hooked into sending unit but just laying on the other end. There is a plastic box with a red button saying reset.....thought it may go in there. Could this be the cause of no reading on my gauge? How do I test my gauge? Would love to have diagram and location of thermostat for this Mercruiser 2bbl and alpha 1 combo. Ser number of engine trans and outdrive are
Oc601967
Oc726511
Oc559565
I was also wondering the location of the thermostat. does is sit vertical or horizontal. The engine was apparantly rebuilt two years ago with only 66 hours on it. Thought maybe someone did not use proper gasket as the sending unit looks like it may be grounded inside.
Any help woudl be appreciated. Boat is a 89 chaparral 198 limited. I also have a 66 egg harbour 38 foot with twin detroit 6v53's....have mechanic for that one, this new one is just for tubing and fun on the lake. Any help would be great. Looking foward to this site.
 
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