Temperature

[tengals123]

My gauge is fine (tested), my sender wire is fine (new and replaced) I can't get a reading on my gauge. <br />To test I have hooked it up and dropped the brass sender in boiling water and got no reading. Does it need to be grounded to the head to work or is my sender faulty? How do I check?<br /><br />cheers

 

[industriallift]

Re: Temperature

Test the gauge by grounding the wire that goes to the sender to the engine block.The gauge should move all the way to hot.The key must be in the run position. If the qauge moves all the way to hot this assures your gauge and wiring is good. The sender must be replaced. The answer to your question is yes the sender must be grounded to the block. You can test the sender with a multimeter. Attach red lead to the end of sender that the wire attaches to and connect the black lead to the end that threads into the block. If it is a 2 wire sender connect the black lead to the other wire instead of the end of the sender unit. Resistance will decrease as the tempature rises.

 

[Laotzu]

Re: Temperature

Also, the gauge needle should move left to the left pin when you turn on the ignition. You don't say what horse power you have but Mercury has told me that the lower HP motors (60 and less) run cold. I ran the tests and know my sender and gauge are ok but the temp gauge doesn't move even when idling for a long time.<br /><br />Jerry

 

[tengals123]

Re: Temperature

thanks guys, as stated my gauge had been tested and works fine. It's more the sender im looking to test.<br /><br />cheers

 

[Dunaruna]

Re: Temperature

Using the OHM function on the multi-meter, connect one test lead to the body of the sender (thread part) and the other test lead on wire connection terminal.<br /><br />Mercury will have specific readings for your sender, but as a general rule - <br /><br />Stone cold will read a high resistance, as it heats up, the resistance will decrease. Mega hot should read very little or no resistance.<br /><br />Regardless of the exact readings, what you are looking for with this test is a gradual change in readings as the sender heats up.

 

[gss036]

Re: Temperature

I am going through the same thing, just ordered a new sender and it is in the shop for me to pick up next week. They cost about $20, not worth all the hassle of testing forever, so order a new one, hopefully it will work on my 89 200hp Merc. It is not a brass screw in type though. I did the above test and got reading but still the guage on reads 100 degrees. I think my next move may be a water pressure guage so I know that I am getting good water flow.

 

[tengals123]

Re: Temperature

Well I did that and got NO reading at all. So im asuming the sender is up the you know where. I have never even used it.<br /><br />cheers