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Discussion Starter #1
I have noticed that no matter how long I ride (max of 1 hour lately) my temp gauge never gets off the bottom. the fan doesn't come on either except for the other night when it ran for a min after I parked - not sure what the gauge read then. The question is..... should the gauge be reading something? I don't want to get into a hot GA summer just to find out that the bike is running hot and I don't know it. it's been in the 60's here lately.
 

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1986 VN750
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I have noticed that no matter how long I ride (max of 1 hour lately) my temp gauge never gets off the bottom. the fan doesn't come on either except for the other night when it ran for a min after I parked - not sure what the gauge read then. The question is..... should the gauge be reading something? I don't want to get into a hot GA summer just to find out that the bike is running hot and I don't know it. it's been in the 60's here lately.
I ride along the coast, which is usually in the 60s. It takes me 5 minutes or more to get her to the second notch on the left when I warm her up.

Now, as long as I sustain speed, the needle will hug the second notch on the left. If I stop, or get in a heavy traffic situation, it will rise up. I've never seen it past 50% myself, but it has been cool here while I have been riding.
 

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that sounds just about right. I find that riding in the 60s is right around the 2nd notch. If i stop, a little more or climb a long hill. If its 90+ outside. Its about 50% always.
 

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Linkmeister Supreme
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There is a temperature gauge testing procedure on page 336 of the Clymer manual.

Take off right side steering head cover. (also says the fuel tank should come off. not sure if you need the room or not??)

Disconnect the yellow lead from the thermostat housing.

Turn ignition switch on
Temperature gauge should read "C".

Attach a short jumper wire to the yellow wire electrical connector.
Touch then release the wire to a good ground.
The gauge should read "H".
Disconnect jumper from ground immediately or it will damage the gauge.

If the readings are correct the gauge is ok, but the coolant temp sensor may be faulty.

If the readings are incorrect the gauge is faulty or the electrical wiring between the gauge and the yellow electrical wire connector is faulty.




The Coolant Temp Sensor test is on page 339.

You need a small container full of a 50:50 mix of coolant and water.
(Drain enough coolant from the system so it is below the upper rad hose and doesn`t leak on the bike when the sensor is removed.)

A way to suspend the sensor`s threads in the coolant.
Don`t let the sensor or thermometer touch the pan while heating or the readings will be off.

A shop or candy making thermometer.
An ohm meter.

Short explanation of procedure now. Ask if you need more help.

Resistance beween terminal and side of sensor should be infinite (no continuity) at room temp.

Slowly heat coolant to 80*C (176*F).
Resistance should be from 42-62 ohms at this temp.

continue to heat coolant to 100*C (212*F)
resistance should reduce to 22-33 ohms

If it fails either test it is faulty and needs to be replaced.

Use light coat of silicone based sealant on threads of sensor when installing, and tighten securely.

Use some dielectric grease on the electrical connection to prevent corrosion.
 

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1986 VN750
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that sounds just about right. I find that riding in the 60s is right around the 2nd notch. If i stop, a little more or climb a long hill. If its 90+ outside. Its about 50% always.
X2 Same here
 

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HAWK
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YOu could have a thermostat stuck open which will not allow the motor to heat up properly.
feel the hoses and see if they are hot or not.
 

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Discussion Starter #8
There is a temperature gauge testing procedure on page 336 of the Clymer manual.

Take off right side steering head cover. (also says the fuel tank should come off. not sure if you need the room or not??)

Disconnect the yellow lead from the thermostat housing.

Turn ignition switch on
Temperature gauge should read "C".

Attach a short jumper wire to the yellow wire electrical connector.
Touch then release the wire to a good ground.
The gauge should read "H".
Disconnect jumper from ground immediately or it will damage the gauge.

If the readings are correct the gauge is ok, but the coolant temp sensor may be faulty.

If the readings are incorrect the gauge is faulty or the electrical wiring between the gauge and the yellow electrical wire connector is faulty.




The Coolant Temp Sensor test is on page 339.

You need a small container full of a 50:50 mix of coolant and water.
(Drain enough coolant from the system so it is below the upper rad hose and doesn`t leak on the bike when the sensor is removed.)

A way to suspend the sensor`s threads in the coolant.
Don`t let the sensor or thermometer touch the pan while heating or the readings will be off.

A shop or candy making thermometer.
An ohm meter.

Short explanation of procedure now. Ask if you need more help.

Resistance beween terminal and side of sensor should be infinite (no continuity) at room temp.

Slowly heat coolant to 80*C (176*F).
Resistance should be from 42-62 ohms at this temp.

continue to heat coolant to 100*C (212*F)
resistance should reduce to 22-33 ohms

If it fails either test it is faulty and needs to be replaced.

Use light coat of silicone based sealant on threads of sensor when installing, and tighten securely.

Use some dielectric grease on the electrical connection to prevent corrosion.
Thanks - I will give it a test this afternoon - My guess is that it is the gauge because the fan came on today when I parked but he gauge still read down on the bottom - hadn't moved a bit.
 

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I warm mine up to the second mark on the centerstand, before even taking off. During freezing weather, I have had it drop back down almost to the far left, which is not good, as that second mark is minimum operating temperature IMO. I thought about carrying something to cover the radiator when it is super cold, to keep from losing heat to the cold air blowing through it, but never have. If you let it set and idle on the centerstand for several minutes, and the gauge does not move, something is either wrong with the gauge or the sending unit, hopefully the sending unit. I believe the sending unit also turns the fan on.
 

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Check your coolant level at the cap on the neck if it is a little low there the sensor will be out of the water and not read high enough.It doesn't matter that the overflow tank is full there may be an air pocket at the top of the system.

I experienced the same problem you are describing and the level was low in the actual cooling system.Not the overflow tank,if it is not full when cold the cap will not function properly and move coolant between the reservoir and the cooling system as needed.When you fill it up use the bleeder screw on the t-stat housing to bleed the air out and you will know it is full.:smiley_th
 

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Discussion Starter #11
Thanks - I will give it a look tomorow - The fan actually came on yesterday for a brief time when i parked it
 

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Linkmeister Supreme
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7,960 Posts
I warm mine up to the second mark on the centerstand, before even taking off. During freezing weather, I have had it drop back down almost to the far left, which is not good, as that second mark is minimum operating temperature IMO. I thought about carrying something to cover the radiator when it is super cold, to keep from losing heat to the cold air blowing through it, but never have. If you let it set and idle on the centerstand for several minutes, and the gauge does not move, something is either wrong with the gauge or the sending unit, hopefully the sending unit. I believe the sending unit also turns the fan on.
Sorry to contradict you Jerry, but the gauge sending unit and the fan switch are two separate units.

The sending unit for the temperature gauge is located up top beside the radiator cap, and has a yellow wire connected to it.

The fan switch is located down on the bottom left side of the radiator.
 
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