Engine Temp sensor

[britinusa]

Our boat is 30 minutes travel from home, so I like to be prepared before heading to the boat to work on a project.

The engine temp gauge is not working, can someone point out where on the engine the temp sensor is located.

Is it a block temp sensor or coolant temp sensor and where is it located.

I was thinking of installing something like this

Thanks.

Paul

[Stu Jackson]

Paul,

The tech wiki under engines has a link to a discussion of..oh, here it is:

Thermostat Sender Source http://c34.org/bbs/index.php/topic,7985.0.html

Here's a picture of the engine:  http://www.marinedieseldirect.com/universal/200157/universal-owners-manual-m25xp-specifications.html

and

http://www.marinedieseldirect.com/universal/200157/universal-owners-manual-m25-specifications.html

Pretty much the same by pictures.

tag  engine picture

[Craig Illman]

Paul - My gauge was seeming to read low, so I replaced with this on my M3-20:  http://www.amazon.com/gp/product/B001RIAJ46/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

$9 was easier to swallow than the price from a Universal dealer or Catalina Direct. Gauges are only about $25-$35. You probably should check wiring continuity first. Ground the sender wire from the Thermostat housing to the block and see if the gauge goes to max.

Craig

[KWKloeber]

Our boat is 30 minutes travel from home, so I like to be prepared before heading to the boat to work on a project.

The engine temp gauge is not working, can someone point out where on the engine the temp sensor is located.

Is it a block temp sensor or coolant temp sensor and where is it located.

I was thinking of installing something like this

Thanks.

Paul

What does not working entail?  Dead?  gauge pinned low?  gauge pinned high?
If you search on "gauge troubleshooting" on the TechWiki, there's a guide I had posted.

See the below for the location of the temp gauge sender - on the front of the thermostat cap, 1/4" NPT thread port.

Do you still have the gummy bear plug at either end of the engine-to-cockpit panel harness?

[attachimg=#]

Ken

[britinusa]

Thanks guys,

The Gauge seems to be reading a max of 2 indents from the lower limit (not sure what temp that is without going down to the boat to look closely)

Other than not being able to find where the wires run, I should not have a problem testing the wiring.

I'm going to follow the links suggested to see where they go.

Paul

[britinusa]

Here's a pic of the Temp Sensors (at least I presume that's what they are!)

[Craig Illman]

My guess is that the one pointing forward is the original sender for the gauge and the one pointing starboard is an added high temp alarm sensor.

Craig

[britinusa]

Thanks,
I hope to get the chance to test them today, will just short them to earth and should get full deflection at the gauges.

If not, then I'll take the control panel off and short them C to earth there that should tell me if I need to replace the Gauge, Wire or Sensors.

Paul

[KWKloeber]

Thanks,
I hope to get the chance to test them today, will just short them to earth and should get full deflection at the gauges.

If not, then I'll take the control panel off and short them C to earth there that should tell me if I need to replace the Gauge, Wire or Sensors.

Paul

Again, the one with the slide on "Packard 56" terminal is not a temp sender -- and has nothing to do with the gauge.  It's a switch that closes around 200F, completes a circuit, and sounds the alarm.  The sender with the post terminal is the gauge sender.  Check it per the troubleshooting guide I posted for resistance before you pull the panel.

kk

[KWKloeber]

I was thinking of installing something like this

Thanks.

Paul

That link is an alarm, and you already have an alarm (driven by the temp switch on the thermostat cap.)  If the alarm isn't working as well, you can replace it with a Cole-Hersee dual alarm/light that mounts thru the panel, or simply a piezo alarm from Radio Shack. My guess is that the alarm is working.

kk

[KWKloeber]

Thanks guys,

The Gauge seems to be reading a max of 2 indents from the lower limit (not sure what temp that is without going down to the boat to look closely)

Other than not being able to find where the wires run, I should not have a problem testing the wiring.

I'm going to follow the links suggested to see where they go.

Paul

So, it's reading LOW. 
Again, do you still have the gummy bear plugs in place at the engine and/or cockpit ends of the wiring harness?

See reasons for inaccurate gauge readings, and how to verify:
http://c34.org/bbs/index.php/topic,8493.msg59876.html#msg59876


kk

[KWKloeber]

I was thinking of installing something like this

Thanks.

Paul

That link is an alarm, and you already have an alarm (driven by the temp switch on the thermostat cap.)  If the alarm isn't working as well, you can replace it with a Cole-Hersee dual alarm/light that mounts thru the panel, or simply a piezo alarm from Radio Shack. My guess is that the alarm is working.

kk

BTW, that's a Japanese engine! Good luck screwing an american' NPT-thread sensor into JIS / BSP threads!     That's why some engines had bolt on sensors on the exhaust manifold.

kk

[Ron Hill]

Paul : The temp sensor is the one pointed forward in Paul's picture.  The wire should be brown with a ring connector.
Also make sure that you put a protective boot on that connection.  If the metallic insulation on the steps touches that connection you'll get an erroneous reading!!

A thought

[britinusa]

A picture gets great responses.

Thanks guys.

I'll check the wiring and get a boot on that sensor.

Ran out of time and energy today. Got a lot done, but exhausted. Working to get the boat ready for the renaming ceremony next weekend.

Paul