Temp gauge does not stay in the middle of the dial, why?

[beemrdon]

The title says it all. Why doesn't the temp gauge climb to the middle of the dial and stay there, regardless of the ambient temperature? This has always puzzled me. I have owned numerous liquid cooled automobiles and each of them warmed up to running temp and stayed there, unlike my K bike.
........Anyone got an explanation?       :dunno   I dunno...       

[The Mighty Gryphon]

First off, my bikes don't normally run in the middle of the range.  Rather the gauge reads about 1/3 of full scale normally.  In traffic, the gauge rises to about mid range which is where I will turn on the fan over ride which usually brings the temperature down to the 1/3 mark.

I think the consensus is that these bikes have radiators sized for moving down the road and not for idling in traffic.  Because of that, you will see the temperature rise in that situation.  A motorcycle just doesn't have the room to put in a large radiator and still have the styling people want.

One thing that will help is to make sure your cooling system is scrupulously clean, especially the radiator core.  On my 4v RS i had to flush it twice, once with the radiator off the bike using vinegar to keep it from overheating.  If a previous owner used hard tap water to fill the system, there can be a very large amount of insulating mineral deposits coating the internals.

[Laitch]

Another reason why I prefer just the light—obsession control. :giggles

[The Mighty Gryphon]

I rather enjoy the stress the gauge induces in traffic.   Makes it that much more pleasant to get moving again.

[Laitch]

I rather enjoy the stress the gauge induces in traffic.   Makes it that much more pleasant to get moving again.

I need not gild the lily.  :oldguy:

[K1300S]

this is why car manufacturers have gone to "idiot gauges".  the gauge in pretty much any car made since the 90's does not actually read the temperature.  after a certain amount of time, the needle gets to the middle...then stays there until the car over heats when it moves to the red.    over the normal variable range of engine temperature, the gauge will sit dead center in the middle.  this prevents all the extra service calls when customers wonder why the gauge is moving up and down.

not kidding.  modern temp gauges are just fancy warning lights.  the tranny temp gauge on my truck hits the middle in about 5 minutes of idling...without even putting the tranny in gear.  I also have a digital temp readout straight from the ECU....it reads ambient temp, not warm for the tranny.   don't believe your stock car temp gauge.

[Laitch]

. . .   don't believe your stock car temp gauge.

I believe everything my '97 Ford's gauge tells me. It fluctuates subtly on inclines and when the engine's under load. Maybe it's just wearing out.  :yes  The windows operate by crank and it has windwings. It's a truck to believe in.

[jakgieger]

Don, the gauge on the K actually works ...if it is operating correctly.  +1

this is why car manufacturers have gone to "idiot gauges"

= an idiot light!

On my new tractors, the gauge still works, as this is a critical function of a diesel motor that actually works.  The  heat range is rather startling...cold day- won't even register, June field work=3/4 mark, August baling hay w/plugged radiator=pegged out!! :eek:

[beemrdon]

Jack, I'm not questioning the accuracy of the gauge. My curiousity is in why the cooling system does not behave in the same manner as all of the other liquid cooled vehicles that I have ever owned. With all of these other vehicles (automobiles) they started out cold (no matter the temperature) and proceeded to warm up to operating temp, which was/is where the gauge needle is more or less centered in the middle of the range - between hot and cold, again, no matter the temp.
I was riding my bike - the K1100 LT -  this last Sunday where the air temp was in the high 50's and the needle never got to midway, but stayed on the cool or left side for the whole trip. On the other hand, I rode it from Massachusetts to Las Vegas last October and it was hot down south in Texas, New Mexico and Arizona. The needle was about 2/3 of the way to hot even though I was traveling at speeds well above 70mph a lot of the time and you would have thought that the air/coolant flow would have been enough to cool the motor better.
I am just trying to obtain a better understanding of this vehicle... and of other K bikes in the process.
I would appreciate having others chime in that what I am experiencing is either "normal" for these bikes or I need to get mine checked out for a possible problem- cooling system flush, etc.
My K does not run as cool as TMG's 3 bikes from what he states.... but is my bike within the range of normal?
So, that is my purpose. To stay ahead of any potential problem$ "down the road".

[Martin]

Check your thermostat, it's job is to control the temperature by controlling the flow of water through the radiator. As the temperature rises the thermostat should open more, allowing more flow through the radiator thus cooling the water, if  the temperature falls the thermostat should close allowing slower flow allowing the water to heat up. The temperature on shown on your gauge will vary but failure to warm up quickly points to a faulty thermostat. The same if it overheats. The bricks cooling system also needs to be clean, only use distilled water and a good coolant and stick to one type of coolant as some coolants are not compatible and can form a jelly when mixed.
Regards Martin.

[beemrdon]

Thanks Martin,
I may just invest in a new thermostat. Can't cost that much.
I use BMW antifreeze 1:1 with distilled water.
I also might try to hook up a manual fan switch for hot weather but my electrical skills are just short of non-existant.

[jakgieger]

Don, Your gauge is operating similar to mine...below half in cool weather, and then above half in hot weather.  If it gets very far above half, I trip my over-ride switch.  IMHO the K does not have "excessive" cooling capacity (size restricted radiator) due to design.  This only becomes a problem in hot weather and traffic under normal operating conditions.  In general, a warmer motor is more efficient with a longer service life.  The over-ride is super easy to accomplish.  Re-read this an just do it!!

[The Mighty Gryphon]

I would say that your cooling system isn't that bad, and your gauge is probably working properly.   The scale of the gauge only covers a range of about 50F so small temperature changes will appear as fairly wide swings in the needle. 

As far as the thermostat, as long as the engine warms up in under 5 minutes and doesn't go into the red unless you are stuck in traffic on a hot day, I would say that it's working properly. 

Because of lag in the flow of coolant from the temperature sensor to the radiator and the operation of the thermostat, there will naturally be some temperature swing as the system responds to changing heat loads.  That the sensor is somewhat remote from the thermostat will also cause some swing in readings as well.  Bugs in the radiator fins will reduce airflow and result in slow cooling response and wider temperature swings, too.

Bottom line, if it warms up and doesn't overheat when going down the road I wouldn't worry.  Plan on doing a good flush the next time you change coolant.  Check the cooling fins for bugs and dirt and maybe clean them out.  Mix a good antifreeze(doesn't have to be BMW) at a 40/60 ratio with distilled water and you will be good to go.

[Martin]

If your thermostat is working it should show cold on the gauge, as the water heats up it will get to the point where the thermostat opens. At this point the needle should jump up to normal. If the needle just goes up slowly it points to the thermostat being jammed open. If it overheats it can be caused by the thermostat being jammed closed. Thermostats are an important part of the cooling system and should never be removed in there entirety. In an emergency the inner part can be removed leaving the outer ring in place. The ring acts as a flow restrictor and if removed can cause the engine to overheat, as the water flows through the radiator too quickly for the coolant to be effectively cooled.
Regards Martin.

[beemrdon]

Thanks guys,

I'll re-read all of your suggestions and bookmark this post for further mulling over.

[The Dude]

Worth checking the pressurisation of the system when hot.I do this by squeezing the hose going through the RHS engine cover.If flacid check the radiator cap is functioning and observe the overflow tank behaviour.
I have no temp guage and if in doubt I feel the engine case(glove off)and if I get pain,I know I'm in trouble.

[beemrdon]

...."and if in doubt I feel the engine case(glove off)and if I get pain,I know I'm in trouble."
In more ways than one. :mbird