Mariner magnum 3 150HP....temp sensor

[jinxd12]

I would like to install an aftermarket temp sensor for my motor, can anyone provide info on where to locate it?

 

[Dukedog]

is sensor like merc "production" or is it actual water temp sensor?.. if its actual water temp you will need to drill and tap one of two places on tha power head for sensor.. most put it on tha port side block, on top above tha head, but have ta make sure it clears tha t-stat...

tha second place is in tha divider plate.. top left corner.. just above tha two center bolts and just below tha outside edge bolts.. kinda had to describe..

 

[jinxd12]

I am looking for the easiest way possible, is there a pic you can post of said "divider"

 

[Chris1956]

Some of those V6 Mercs had a temp sender for a gauge, and a temp overheat alarm sensor, one on each head. Check the wire color from each sensor. If they are the same, then you have two alarm sensors. If they are different, you likely have one of each.

 

[Chris1956]

BTW - a water pressure gauge is much better than a water temp gauge, on an outboard.

 

[jinxd12]

Ok, i guess i would prefer to add a visual gauge of some sort, near the dash. Can i get some help on how to go about this?

 

[Dukedog]

simplest way.. try a merc dealer for gauge AND sensor.. temp gauge sensor has a tan/blue PLUS A BLACK ground.. goes in port head.. over temp sensor that you should have in starboard head will be tan/blue also but NO ground..

there will be a tan/blue or just tan in tha harness on tha male side that's not being used.. that will plug into tha GAUGE tan/blue sensor wire.. it goes to tha console to be used on a temp gauge when installed..

sorry, no pics of tha places for an actual water temp sensor.. will did a little farther later tonight.....

 

[Chris1956]

Gee, water pressure gauges mount on the dashboard. They have a pressure tube that runs to the cylinder head of the motor, giving a visual indication of the water pressure in the engine block.

 

[Dukedog]

this is install of tha "water temp" sensor but on wrong side.. needs ta be same place but on "port" side......

pressure gauge tube will go in tha hose that starts on top of block and goes down to tha poppet cover on starboard side.. you will need to use a "T" fitting at tha top of that hose adapting from 5/15" hose to tha (normally 1/8") hose for tha gauge going to tha dash gauge......

 

[jinxd12]

i have a water pressure gauge on the dash, i figured adding something for temperature would be an added benefit, is the consensus it is not needed? I suppose i was thinking knowing the motor temp would be a nice add on

 

[Dukedog]

I use ta install a bright red led in tha over temp circuit ta get my attention if a coolin' problem shows its ugly face... only problem with a gauge is gotta LOOK at ta know.. that usually happens when tha over heat buzzer goes off.... its nice ta have ta make sure that ya got heat in tha motor and temp and ok to hammer it after first start though.....