What does a temp switch do?

[jesse_h97]

In the manual it states the temp switch opens at 147F is this what allows water to the head?

 

[j_martin]

Re: What does a temp switch do?

It might help to know what engine you're talking about.

 

[joed]

Re: What does a temp switch do?

I would guess that might be the overheat sensor. It sets of the alarm at 147??

 

[jesse_h97]

Re: What does a temp switch do?

sorry, its a 1995 merc 90 lpto. The manual says opens at 170F closes at 190F

 

[Texasmark]

Re: What does a temp switch do?

147F is where OB thermostats open and in doing so, allow water to circulate through the head and around the cylinders....the exhaust usually gets a continuous uninterrupted supply.

It is a switch, but we usually associate it with the name thermostat. Also, a switch is commonly thought to be a digital (1/0) sort of critter. A thermostat is more of an analog function (starts opening at spec temp, more or less, and continues to open wider as temp rises until fully opened).

On newer engines there is a temperature switch. It is the overtemp switch that usually monitors the water in the area of the heads and is set to short out, grounding the circuit at around 190F. This action causes your horn to blow continuously.

Mark

 

[jesse_h97]

Re: What does a temp switch do?

Sorry the thermostat works fine, I pulled it and ran some hot water on it. This is a little round looking cylinder at the base of the power head under a terminal block. The temp sensor is attached to it as well. its labeled P under my repair manual wiring diagram.

 

[jesse_h97]

Re: What does a temp switch do?

thanks! to test that I pulled that wire and grounded it to the block and it sounds the alarm. Will the alarm sound if there is low voltage? With engine running the battery reads 11.9v and the alarm is very low and squeaky in fact I had to jump it with the truck. Ive since unplugged all the bilge and light wires which look very bad. I believe the poor rpm's are from not being run in 10 years and old plugs.

 

[j_martin]

Re: What does a temp switch do?

thanks! to test that I pulled that wire and grounded it to the block and it sounds the alarm. Will the alarm sound if there is low voltage? With engine running the battery reads 11.9v and the alarm is very low and squeaky in fact I had to jump it with the truck. Ive since unplugged all the bilge and light wires which look very bad. I believe the poor rpm's are from not being run in 10 years and old plugs.

Keep it up and you'll burn it down and make an anchor out of it.

Check this link, and put the engine in proper condition before you try to run it.

Waking UP a Sleeping Outboard

The switch in question is the overheat alarm switch. It sounds the alarm if cooling fails.

hope it helps
John

 

[jesse_h97]

Re: What does a temp switch do?

thanx, but i believe its too late I'm sending it to a proper mechanic.