temp sender unit location needed ??

[dart]

hi fellas
i recently brought a go-kart two stroke digital temp sender unit to put on my late model 50 hp short shaft 3 cylinder/3 carb mercury (tohatsu) engine.
i have tried 2 different locations to put the sender unit in,one in the cooling jacket of the middle cylinder head and another location in side of block where water outlet goes thru.
it only reads approx 18 degrees celcius!!
i did a test to check sender unit working properely by placing it in boiling water on stove,it reads close to 100 degrees celcius boiling point,so the guage is working properly.
so where should i position the sender unit correctly to measure engine temp please ???
thanks
glen

[Fastjeff57]

Stupid question: Is that motor equipped with a thermostat?

Jeff

[dart]

Stupid question: Is that motor equipped with a thermostat?

Jeff

hi mate,not a stupid question at all,yes it is fitted with thermostat fred!!
any idea where i could position this temp sender unit to properely read temp of engine please ??
thanks
glen

[Bill Van Steenwyk]

hi mate,not a stupid question at all,yes it is fitted with thermostat fred!!
any idea where i could position this temp sender unit to properely read temp of engine please ??
thanks
glen

Some cyl head temp gauges read from a small gasket that fits under the spark plug and looks like a regular spark plug gasket, unless this is strictly a water temp gauge instead of a CYL HEAD TEMP gauge. If you bought this used or from someone else not new, are you sure you got all the material that went with it.

Also possibly contact the mfgr of the gauge and see if they have any suggestions. Unless it is no longer made, most are on the web these day.

[phillnjack]

you need to put the sender high up the block
ideal would be about halfway up the first cylinder (level with plug) use a head bolt and make a small z bracket.
this is where the evinrude triples of the 90's had a facility with a threaded hole in it.
the mercs and any engine should always have the sender high up.
hotttest point is at the top as heat always rises.
make sure the sender is touching the head not just the water jacket, the water jacket will only give low reading.
i got 29c from mine, but head temp was 55c !!! big difference. head temp is what you need.
this will give you a good idea if the engine ever overheats etc.
I have just fitted temp guage to my rude 60 triple, its far better than waiting for alarm telling you that the engine has just cooked itself.
all the temp alrms are set way too high, they dont allow for any extra etc.
If you run at around 60-70 c and then see guage rise upto 80-90 you know something is wrong.
a temp alarm dont go off untill way over 100c, and that is too hot for my liking.



phill