Temp gauge not working

[victuono]

Hi all,

Newby here. I just bought a '97 Sylvan 178 with a 3.0 Mercruiser. The temp gauge is not working. Water seems to be circulating ok. When I hook up the muffs and run it, warm water comes out of the exhaust post on the right side of the lower unit. I am new to boats, but I am somewhat mechanically inclined. I pulled the thermostat out and tested it, it seems to be opening and closing ok (it was closed when i took it out). I'm not sure if the next suspect should be the sending unit, the gauge, or somewhere in between. Any help on my next step would be appreciated.

Thanks

 

[achris]

Re: Temp gauge not working

:welcome:

With temperature gauge faults you need to check a few things.
1. Power and ground at the gauge are good.
2. Sender is grounded properly. (ie, NO thread tape)
3. Wire from sender to gauge is good.

Once you verify the above, then turn the key to ON and ground the sender wire on the engine block. It should peg the gauge to the HOT end. If it does, suspect the sender. If it doesn't peg the gauge (it stays COLD) then suspect the gauge itself. The only other test I would do is on the back of the gauge, short the sender wire to the ground wire. Again looking for the gauge to peg HOT....

Chris.........

 

[victuono]

Re: Temp gauge not working

Thanks, I found another thread right after I posted. grounded the sender wire and pegged the gauge. Will try replacing the sender.

 

[victuono]

Re: Temp gauge not working

Thanks again. It was the sender. I'm sure I'll have more questions going forward. Great forum!