Mercruiser 4.3 Thermostat Sealant

[BobMaio]

I have a 4.3 Mercrusier. I am getting an occasional warning alarm that I have traced to the thermostat sensor. The manual says to install the gasket (with the rivets) using perfect seal. Which I did. I am pretty sure that it is the perfect seal that is compromising the conductivity of those rivets. Trouble is, how do you apply the sealant without it getting on those rivets. I am kinda leaning towards installing it without any sealant. Any suggestions?

 

[QBhoy]

Hi
my head is scrambled today, but where is the thermostat sensor you mention on the 4.3 ? Is it the water temp sensor ?

 

[BobMaio]

On the stbd side is the sending unit for the gauge. On the port side is the sensor for the alarm. They are both in the thermostat housing.

 

[BobMaio]

The thermostat gasket has 4 rivets in it that are used to conduct ground to the sensor.

 

[Bt Doctur]

Most alarms work by providing the ground .if your getting an alarm its working

 

[bman440440]

I have a 4.3 Mercrusier. I am getting an occasional warning alarm that I have traced to the thermostat sensor. The manual says to install the gasket (with the rivets) using perfect seal. Which I did. I am pretty sure that it is the perfect seal that is compromising the conductivity of those rivets. Trouble is, how do you apply the sealant without it getting on those rivets. I am kinda leaning towards installing it without any sealant. Any suggestions?

use the perfect seal in the bolts that mount the thermostat housing... I have never needed sealant on the gaskets themselves so far with working on them for MANY years

 

[BobMaio]

Thanks for the response. Sounds like I will skip the perfect seal on the gasket itself.

 

[achris]

Perfect seal on the bolt threads, gaskets remain dry.

 

[alldodge]

I am getting an occasional warning alarm that I have traced to the thermostat sensor

What alarm are you getting?
Solid horn, beeps,

 

[BobMaio]

What alarm are you getting?
Solid horn, beeps,

Beeps intermittently, but consistently. 3 causes: Gear Lube, Oil Pressure or Thermo. I unplug thermo sensor and beeps stop. Temp gauge reads correctly.

 

[alldodge]

Maybe the switch is the problem and not the gasket. As BT mentioned, they turn ON by applying a ground. If you where not making a good ground then the alarm would not come ON. So if your gauge is accurate and your not overheating, then its the switch

 

[BobMaio]

When I pulled the thermostat housing off, the gasket was still attached to the housing. So I was able to test the conductivity and found 3 of the 4 rivets were not conducting ground because of the sealant. However one was. Thanks to everyone's input here is the plan. I ordered a new sensor and when I install the unit I will only apply perfect seal to the bolts and not the gasket.