Easier way than cigarette lighter to test sensor?

[dogtoter]

I searched the forums for 'test heat sensor' and a poster said that a cigarette lighter flame is needed to test the little brass sensor next to top plug and connected to the tan wire of my 1995 merc 40 hp 4 cyl. He said it activates at 240 deg to sound the alarm.

I broke mine and a friend is gonna try to reconnect wire to sensor. Is there an easier way to test it?

 

[Moody Blue]

Re: Easier way than cigarette lighter to test sensor?

Not sure if the sensor is the same or not, but on my 1992 40hp 4cyl Mariner (same as Merc) I dropped the sensor into boiling water and it triggered the alarm.

 

[crappiejig]

Re: Easier way than cigarette lighter to test sensor?

Assuming you have an electric start with remote controls,simply put ignition switch to on,and ground the terminal end of the tan wire. Horn should sound. Warning horn has 12v to it whenever ignition switch is on,and the ground to complete the circuit and sound the horn is made by the temp switch reaching its design limit. (my switch grounds at 260 degrees).

 

[dogtoter]

Re: Easier way than cigarette lighter to test sensor?

Thanks, if I could combine what crappie and blue say...

I need ann easy way to get the sensor up to 240-260 deg and then touch the sensor to the engine to test if it has closed the open citcuit inside the tiny brass sensor (smaller than a peanut - like a small hex head on a 3/16" length of brass threads and the tan wire connected to the bolt head.

 

[crappiejig]

Re: Easier way than cigarette lighter to test sensor?

You really just want to make sure that your friend repaired the wire, correct? Or do you think for some reason the sensor itself (the metal part in the block) is defective? My procedure above explains how to make sure your wire repair is serviceable. Do that procedure to get the horn and if you dont get the horn that way,you never will even if you heat to 300 degrees!! First verify the wire repair,then worry about heating it up,which I contend is unneccesary for a previously known good sensor. Good luck.

 

[dogtoter]

Re: Easier way than cigarette lighter to test sensor?

Thge tan wire broke at the sensor head. The sensor was working fine.

I am sure if I touch the bare tan wire to the block, the key alarm will sound, but once the tan wire is soldered to the little sensor head, how would one test the repaired fix?

My concern, I guess, is of the delicate nature of the tiny sensor vs the rather more unprecise electrical solder fusing of wire to sensor head. I may be overthinking it.

 

[dogtoter]

Re: Easier way than cigarette lighter to test sensor?

Update

Friend soldered the tan wire to brass sensor, we put it in, turned on key, and no alarm -- so far, so good.

Since he did not work on the threaded side of the sensor that was in working shape, I will assume she is fixed. Yah! (I'll be cautious for a while, though!!)


Thanks to all for helping this cadet!