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Temp Gauge Problems

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cyborgx

New member
Hi Guys,

Having an issue after 3 weeks of sitting started up my mercruiser 5.0 tks bayliner capri cuddy.. temp gauge
not moving everything else is and engine seems to get up to temp fine.

I have since replaced the temp sensor and installed a new quiksilver gauge to match the mercruiser sender,
still not working. I have tried different power/ground if i short the sensor wire to the block the gauge goes down?

Does the same with the old gauge and all other gauges are working.

I am getting very frustrated haha, could it be a break in the sender wire? but if that was the case why does it go down when i ground it ..

Manifolds and thermostat less than 12 months old all original mercruiser.
 
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You have continuity from sender wire to gauge wire, of course, yes? And of course you have power to the gauge, yes? The flow of electricity is through the gauge to the sender which grounds on the engine block. Somewhere in that pathway the electrons have stopped moving. My guess is somewhere in the dash harness, or the multi-plug at the engine.
 
I have tried different power/ground if i short the sensor wire to the block the gauge goes down?
Click to expand...

Ayuh,.... That's backwards,..... It Should peg the gauge to Hot,....
 
o2batsea said:
You have continuity from sender wire to gauge wire, of course, yes? And of course you have power to the gauge, yes? The flow of electricity is through the gauge to the sender which grounds on the engine block. Somewhere in that pathway the electrons have stopped moving. My guess is somewhere in the dash harness, or the multi-plug at the engine.
Click to expand...

Hi o2batsea,

Yeah I agree harness or multiplug is definitely likely at this point, if I ran a 12volt connection off my battery box and a wire straight to the temp sender the gauge should theoretically work for testing?
 
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cyborgx said:
Thermostat was done by previous owner and gauge has been working for 12months since I've had it
Click to expand...

To confirm proper grounding run a GROUND wire from Battery Neg to threaded body of sender with Key ON and see if gauge works correctly. (engine at temp)

DO NOT touch ground wire to sender post with power on!! Only to threaded body!!
 
cyborgx said:
Thermostat was done by previous owner and gauge has been working for 12months since I've had it
Click to expand...
What says he did it right?

Get a new, correct gasket and check it. Using the incorrect gasket will work until it doesn't.

Once you figure out the continuity issue, you can correct the polarity.
 
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kghost said:
To confirm proper grounding run a GROUND wire from Battery Neg to threaded body of sender with Key ON and see if gauge works correctly. (engine at temp)

DO NOT touch ground wire to sender post with power on!! Only to threaded body!!
Click to expand...


Hi kghost,

So touch the battery ground on the red thread going into the thermostat housing?
 
cyborgx said:
Hi kghost,

So touch the battery ground on the red thread going into the thermostat housing?
Click to expand...



The threaded body is the ground path for the sender. The brass threads must make contact with housing so if too much red stuff is there, clean it off so at least a few threads make contact with housing.

If the SENDER is in the thermostat housing (not the intake manifold), as Chris mentions, then the thermostat housing base gasket MUST have brass/Copper continuity washers built into gasket to establish the ground path for the thermostat housing.

If a loss of ground is your issue sometimes tightening the thermostat housing bolts a little more (IF the correct gasket is in place) may re-establish the ground path...........
 
Last edited:
kghost said:
The threaded body is the ground path for the sender. The brass threads must make contact with housing so if too much red stuff is there, clean it off so at least a few threads make contact with housing.

If the thermostat is in the thermostat housing (not the intake manifold), as Chris mentions, then the thermostat housing base gasket MUST have brass/Copper continuity washers built into gasket to establish the ground path for the thermostat housing.

If a loss of ground is your issue sometimes tightening the thermostat housing bolts a little more (IF the correct gasket is in place) may re-establish the ground path...........
Click to expand...


Thanks will try what you and Chris recommended, to me it indeed looks like a bad ground.

Thanks appreciate the help
 
kghost said:
The threaded body is the ground path for the sender. The brass threads must make contact with housing so if too much red stuff is there, clean it off so at least a few threads make contact with housing.

If the SENDER is in the thermostat housing (not the intake manifold), as Chris mentions, then the thermostat housing base gasket MUST have brass/Copper continuity washers built into gasket to establish the ground path for the thermostat housing.

If a loss of ground is your issue sometimes tightening the thermostat housing bolts a little more (IF the correct gasket is in place) may re-establish the ground path...........
Click to expand...

Looks like it's the temp wire / harness , I ran a new wire off the sender to the new gauge and its working havent tried the old gauge yet. If I disconnect the sensor wire now the gauge drops which is correct. :cool:

I bought one of those infra-red hand held temp gauge engine on the muffs idling thermostat housing is around 110 -120 f and the manifolds around 120f as well.
 
First place to look is the big black electrical connector at engine.

Pin # 3 Tan wire the male pin and female pin socket in the connector ends. The Male pin is split, You can try to clean it a bit and very carefully put a thin flat blade screw driver into the split and spread the pin apart just a very SMALL amount.
Reconnect plug and retest.

Second place to look,
If that does not work then you will need to look under the dash and follow the sender wire (TAN) backwards to a intermediate connector under dash and check pins for corrosion or issues. There may be more than one so look closely. Check all connections and the ring terminal that connect to the gauge making sure it is a good connection.
 
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