Temperature Guage, 1990 135 Black Max

[Glastron_V210]

Hi all. I am the proud new owner of a used 135. I am in the process of integrating it to my old boat, then I can have some fun!

The one thing I did not get with the engine is the temp guage. As gauges are specific to their resitance/temp curve, I need to get the right one. I've tried searching and researching but haven't come up with much.

Can someone point me to a part number or cross reference which will work?


Thanks,

Chay

 

[Chris1956]

Chay, I believe that motor has a temp gauge sender on one head and an overheat sensor on the other head. The overheat sensor would connect to a buzzer and ground when the motor overheats.

The temp sensor would normally use a standard marine temp gauge. Why not check the resistance when cold and then at operating temp. That will give you the lowpoint and midpoint of the gauge range.

 

[Faztbullet]

Don't waste your money ...install a water pressure gauge as its instant reading.

 

[Glastron_V210]

Good questions.

I don't have a buzzer/switch. There is only the sensor. the other head has an empty threaded hole.

So here's the deal. It seems like these V6 engines have twin thermostats, one for each bank. So, even if your water pressure is good, you could overheat one bank. Likewise the temp guage.

So to have 'foolproof' coverage a guy would have a temp guage or buzzer hooked up for each head. I may do this. It might be overkill, but overheat is a main cause of these engines dying, so I hear.

I don't know if there is a 'standard' marine curve. Hopefully there is. Really all I need to know is normal operating temp, like you say. Then if it's over start investigating. It would be nice to have it somewhat accurate though.


Chay

 

[Chris1956]

Those motors have twin thermostats that open at abut 143*F. They also have a poppit valve that opens at about 2000RPM, to allow more cooling water to bypass the thermostats.

Temp gauges are usually designed so that normal operating temp has the needle centered on the gauge scale.

So if you find a gauge with a 0-400 ohm range, and your temp sender says 200 ohms at running temp, that should work. You will need to consult Ohm's law if you want to connect two senders to one gauge.

 

[Faztbullet]

Add the buzzer which should be under dash, add another sensor on empty head and tie to existing sensor on terminal block and if either bank overheats buzzer will sound. Add the water pressure for extra insurance...

 

[Dukedog]

Good questions.

I don't have a buzzer/switch. There is only the sensor. the other head has an empty threaded hole.

So here's the deal. It seems like these V6 engines have twin thermostats, one for each bank. So, even if your water pressure is good, you could overheat one bank. Likewise the temp guage.

So to have 'foolproof' coverage a guy would have a temp guage or buzzer hooked up for each head. I may do this. It might be overkill, but overheat is a main cause of these engines dying, so I hear.

I don't know if there is a 'standard' marine curve. Hopefully there is. Really all I need to know is normal operating temp, like you say. Then if it's over start investigating. It would be nice to have it somewhat accurate though.


Chay

V6 mercs always came with one sensor and always in starboard head for "over temp".. there is a buzzer somewhere up front unless someone didn't like ta hear it goin' off!.. tha temp gauge and sensor were "options", even when tha efi came out.. tha sensors are completely different even though they look and install a lot alike (except tha efi) it has more wires stickin' out.

what faz says.. you'll hear tha buzzer long before ya look atta gauge.............'specially after ya get comfortable with tha motor being jus fine....

 

[Glastron_V210]

Absolutely right.

I was just looking at that.

On my engine the switch (tan/blue) is in the starboard head and the guage sensor (tan) is in the port head.

I don't have all of the dash gear (No buzzer for example) so I'm looking at adding it to get back to stock. I bought this sucker used and it only came with the tach.

There is another threaded hole, I guess it is an extra spot for something...

Chay