Analog temp guage swinging up and down

[lljjmm]

I have an analog temperature gauge installed on my 2000 Valk Interstate and it has gradually started to swing up and down ( varying between 160 degrees to 180 degrees). At times it will remain remain steady at 180 degrees,  sometimes then flicker a bit, then sometimes swing down to 160 degrees then swing to 180). I have had this gauge installed for about 12 years and has worked fine.

The oem temp indicator light on the bike does not come on at all. Fluid level  has not changed.

Possibilities are - rad cap, thermostat, sensor, gauge.  The gauge is an Auto Meter.

Any words of wisdom where to focus,

Thanks

[Brewer]

My first thought is find a way to check the gauge or measure engine temp separately.

[lljjmm]

To add to my message- My sensor is spliced into the upper rad hose and the bike runs well, also  I just returned from a 2 1/2 hour run and the gauge never stopped swinging for very long.

[John Schmidt]

Your make/model and sensor installation is the same as mine, and has been installed about the same amount of years. My guess is you might have a t'stat starting to act up, but first check your fluid level at the radiator...not the overflow tank.

[lljjmm]

The rad is full of liquid

[Robert]

Seems obvious but I have to ask you have had it for 12 years, is the swing abnormal for the gauge to do?

The temp is ok between those temps, normal at idle is 212 for the fan to come on and switch off at 190 and normal coolant temps are down to 160 to 180 for a aftermarket thermostat and about 190 for a OEM thermostat. Depending on where you have the temp sender located it could be picking up the flow of cooler coolant into and out of the engine. The other explanations are change in coolant, change in thermostat operation or sometimes even totally bleeding air out of the cooling system. You have not given much info to go on, and the temp is not dangerous so really other than the swing what is the complaint?

[longrider]

I have the same setup as the OP.  During the summer months the t-stat on mine will hold 180 or so steady.  When I'm riding and the outside tempos are maybe 60-65 or colder, the stat will allow the engine to warm up and every time it opens a bit the cold coolant will bring the gauge temp down to 150.  It cycles up and down.  If I'm running 80 on the interstate there is enough load on the motor to hold 180

[lljjmm]

The swings are not what it normally operated like, it operated as Longrider's  bike and held firm at 180 at highway speeds and temperature did vary and moved slowly.

These swings are quite radical and swings are quite quick - high to low then back up then may stay steady for a moment then it changes - and have even dropped below 150 and that has caught my attention.

[Robert]

The swings are not what it normally operated like, it operated as Longrider's  bike and held firm at 180 at highway speeds and temperature did vary and moved slowly.

These swings are quite radical and swings are quite quick - high to low then back up then may stay steady for a moment then it changes - and have even dropped below 150 and that has caught my attention.

Quick swings doesn't sound like coolant but more like electrical.

Like someone suggested an external temp gun would be great, if you have one. The other thing is if the upper and lower rad hose feel like they change with the temp. I would believe rapid temp change is more electrical than mechanical if you can verify there is no temp change when the gauge says there is either by temp gun or by simple feel of engine temp that would confirm sensor or thermostat.

[longrider]

180 down to 150 is fairly quick but on the way up it takes a bit depending on the load on the motor   Maybe 20 or 30 seconds at 60 mph.  On your last post you mentioned it swings very fast.  Does it also do it at interstate speeds and what are your ambient temps there. 

[lljjmm]

I does happen at interstate speeds of 65 -80 mph and of course lower and higher.
Ambient temp of outside has ranged from 10 Celsius to over 20+ Celsius when it happens, and it never seems to sit steady as it used to at about  180 at the highway speeds

Maybe I am over analyzing the situation, but never really noticed the large swings before. 

[longrider]

not sure which gauge set you have but you may need to get a new sending unit.  The oil pressure sending unit is available separately but I'm not sure about the temp unit.  Where are you located.

[lljjmm]

I am in Alberta, Canada

[98valk]

it's a bad ground connection, looseness, corrosive, etc.

[longrider]

98 valk could be correct.  check the connections before you go any further.  The hard part is getting at the screw for the sending unit.  Edmonton or Calgary?   I was from just east of Edmonton and now from Vernon.  How did you mount the gauge,  mine on a standard are in chrome pods mounted to the handlebars.  

[lljjmm]

From Medicine Hat.

Will be checking connections, like it was said, the inline temp sensor being behind the rad is the toughest, might have drain the coolant.
I mounted it with a chrome pod like in your picture, only being on an Interstate.

For those that have replaced the thermostat, what kind of a job is that?

[98valk]

From Medicine Hat.

Will be checking connections, like it was said, the inline temp sensor being behind the rad is the toughest, might have drain the coolant.
I mounted it with a chrome pod like in your picture, only being on an Interstate.

For those that have replaced the thermostat, what kind of a job is that?

why are u replacing the stat?   my auto meters have done same shaking needle. ground wire is the fix. my oil pressure gage actully would peg, freaked me out the first time it did it since I was hard on the throttle and all of a sudden it pegged. I thought the oil filter collapsed. but it was the ground at the sender.

[lljjmm]

Just looking at my options, will check ground. Thanks

[old2soon]

Just looking at my options, will check ground. Thanks

             Check ALL the wires and connections that have ANYTHING to do with your temperature gage and temp sender. After 12 years things mite could be a tad crusty. RIDE SAFE.

[lljjmm]

Ok, so I cleaned and checked connections, (one was kind bad) the easy ones. Didn’t get to the sender connection being behind the rad, but sprayed it with electrical cleaner, it appeared clean.
Took it for a run and everything is now working as it should - holds steady at about 180 at highway speeds, no swings or flutter movement of the needle.  Hopefully it stays that way.
Thanks to those who chimed in.

[lljjmm]

Went on a longer ride and all is working as it should, problem would of been a bad connection

[98valk]

 

Went on a longer ride and all is working as it should, problem would of been a bad connection