Engine temperature gage

[Andrew Harvey]

For some reason my temp gage is no longer working.
It reads ambient temperature,but when i turn on the ignition it drops to below ambient.
I have checked wiring, seems to be OK. A/F level is good. Since it does show ambient temperature i think the sensor is OK. I am worried that that the high temp alarm is on the same circuit/sensor and i will not know if there is a problem. Engine seems to be running quite hot since our vacation.
Any one else had experience with this?

Andrew   

[Stu Jackson]

Andrew, I don't understand the use of the word "ambient."  On our boat, when the engine key switch is energized, the temps gage needle is all the way to the left.  As the engine warms up it moves to the right, and eventually reaches the engine operating temperature of 160 or so.  When the engine is turned off, and the key removed, the gage stays at the 160 for quite a while.  This doesn't begin to answer your question about the alarm wiring, but I need some help in understanding "ambient."   As I understand it, the temperature sensor alarm is separate from the temperature gage, with the alarm being initiated from a sensor on the block, and is not from the temperature gage.

[Andrew Harvey]

Stu, Ambient refers to the outside air temperature. For example the guage will indicate about 80 degrees or so. It is too low to register on the scale, but it does show a few degrees higher than the far left ignition on position. I hope that is clear as mud.
Glad to know that the high temp alarm is separate until i get this figured out.

Andrew

[Stu Jackson]

Andrew, it seems that the gage is a goner if it never increases after operating the engine for a while.  The difference on the gage between a "cold" engine and ambient should be none because the engine is only as cold as the air around it, hence "Ambient."  If you've checked, as you said, the wiring and connections, then the only other thing is a faulty gage.  They're made by Teleflex and can also be procured from Seaward.  You should be able to get one in any chandlery, and West Marine certainly has them (we replaced our voltmeter with a Teleflex from WM a few years ago).

[Ron Hill]

Andrew : Before you buy a new gage, make a few more checks.  Take a wire and run it from the sender directly to the back of the gage and see what the gage reads when the engine is running(you could have a broken wire, bad connection or a bad sender).  With the engine off, but the key switch ON, if you jump a wire on the back of the gage from GND to Sender the needle should go all the way over the the right.

BTW, I posted a Seaward Temperature Gage check list of the things to diagnose on our web site.  It's been there for 7/8 years?
You might want to look at it!!    

[Andrew Harvey]

Thanks
I will check it out this weekend.
Andrew

[Ken Juul]

The needle on a DC powered gauge will remain in the same postion where it lost power until power is reapplied.  This weekend I shut the motor down the temp was 160.  Sailed for about 4 hours, the temp remained at 160.  When I turned the key on to restart, the needle dropped to current temp. 

[Andrew Harvey]

Had a friend check out my guage and sender. Turns out it was a wiring issue. I am embarrased to say this but it was the wiring harness plug.
Will be replacing the harness this weekend!