Coolant temp "HI" - Yamaha FJR Forum : Yamaha FJR Owners Forums
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post #1 of 11 (permalink) Old 03-30-2019, 05:32 PM Thread Starter
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Coolant temp "HI"

Last december I did a full maintenance on the bike (2013 FJR, bought used in summer 2018 with just under 30k miles) in my garage using the Haynes manual. Oil change will full synthetic motorcycle oil, not car. I believe it was Shell Rotella. Also, rear final drive with Mobil 1. I did the coolant flush with blow job, including two distilled H2O flushes. Let it get up to temp, then back to room temp, just like the Haynes manual told me. The original coolant was red, BTW. I replaced using Peak Long life 50/50 coolant because it was "everything" free: no borates, phosphates, silicates, etc. Everything seemed fine in December, I burped the system, the fans came on at 220 or 221, and cooled down the bike's temp gauge at idle. Never over heated, or went to "HI". I thought, "I'm a genius!"

First ride of the spring today here in New England, high 50's low to mid 60's, everything seemed great. Bike warmed up, I rode for about 20 minutes to run a errand. Temp gauge seemed fine, anywhere from high 140's to low 160's. I got into an area of stop and go, and I guess it was fine, never paid much attention. Completed my errand at a store for about 10 minutes. Got back into traffic and the temp gauge jumped into the 200's quick. Fans on, temps still climbing, then to "HI". I turn the bike off, for a minute in traffic, then got moving again, temps get back down fairly quickly. Onto the interstate, and temps back to normal quickly. Took a rode thru back roads, noticed coming to stops, and slow downs, the temp gauge jumps up quite "reactively". Cruising normal in the 150's, then would jump to 170 or 180 something when stopped for a moment.

Got home and tested in may garage. Let it idle and the bike slowly climbed in temp, then jumped into the 200's then 220's then "HI". The fans working just fine, temp not coming down, though, after a bit, so I shut off, fans still whirring, then the bike returns to the 220's.

Never over flowed at all at anytime. Coolant level in reservoir seemed to stick just a hair below the line.


1. Did I damage my bike? Valve noise seems a tick louder, I dunno, maybe its been a long winter.

2. Do I need to rid an air bubble that was actually there before or was created today/over the winter storage?

3. Thermostat all of a sudden crap?

4. Water pump crapped? Lord I hope not.

Thanks folks!


Last edited by smadams1065; 03-30-2019 at 05:51 PM.
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post #2 of 11 (permalink) Old 03-30-2019, 06:14 PM
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Almost certainly an air bubble. The temperature sensor is on the end of that metal coolant pipe which goes over the top of the engine valve cover. This is also the highest point in the cooling system, where a bubble is most likely to be trapped. So, the sensor will sometimes be in air, and other times in coolant. This causes those unbelievable jumps in the temp readings, which are not possible in reality.

As for getting the air bubble out of that pipe, don't ask me. I wonder if putting the bike on the side stand, then loosening the sensor so that the air and some coolant can escape would work???

I no longer own an FJR, so I can't experiment, but I have experienced this problem.

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post #3 of 11 (permalink) Old 03-30-2019, 06:58 PM
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As Bernie says, air in system, temp sensor not seeing coolant. If you did the blow job, you essentially started with a system that was almost dry. As I found on the project bike which was totally dry, all the precautions such as filling slow, burping, squeezing rad hoses, etc. can't prevent an air bubble. Started with the overflow reservoir overfilled my normal inch, and after a couple of cooling cycles, it dropped below full, which normally doesn't happen. So, when cold, just top off the rad if it needs it, (squeeze the lower rad hose and the hose at the water pump if you like) top up the reservoir to just over full, and run a cooling cycle or two. As it cools down, it will suck in what it needs to fill the rad/system, and reservoir level will drop to full.
BTW, there is no real need to do a water flush and blow job at all, and of course led to your issues IMHO. Coolant itself doesn't degrade but the corrosion inhibitors get used up. Your new fill will have enough of those to last until your next valve check no problem.
And no, you didn't do any damage. Your valve noise is your imagination, that didn't change either.

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post #4 of 11 (permalink) Old 03-30-2019, 11:38 PM Thread Starter
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Just did pretty much you suggested. Holy cow, was I low! I think I finally got all the air out, but I'll take it for another spin tomorrow A.M. and see what happens. If it goes "HI" again, then I'll just top off some more.


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post #5 of 11 (permalink) Old 03-31-2019, 02:04 AM
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Temp sensor not being immersed in coolant mostly results in a reduction in indicated temp - because air is nowhere near as efficient as conducting thermal change as liquid. Itís a common symptom of rapid fluid loss in a cooling system in a vehicle - a temp spike followed by a decline....then steam....


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post #6 of 11 (permalink) Old 03-31-2019, 06:52 PM
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One last tip, when you Finnish your ride, leave the bike on center stand, with the engine going for about one minute the temperature will go up, an the cooling fans should start up, then turn the bike off to cool down, check the reserve tank level while hot and again when cold to be sure the system is correct.
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post #7 of 11 (permalink) Old 07-09-2020, 02:15 PM
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What is the normal range of coolant temp for Gen III in summer time.

Took my FJR for a spin and temp out was like 94F and the coolant temp hit 224 at stop lights but then came down to 180s once running..

Any insight?
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post #8 of 11 (permalink) Old 07-09-2020, 03:27 PM
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The cooling system relies on fresh air to cool things down. If the air is warm the bike will run hotter.

If the level in the radiator is low check for leaks. If a radiator is heading towards leaking just changing the coolant can be enough to set it off.
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post #9 of 11 (permalink) Old 07-09-2020, 03:52 PM
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Originally Posted by kukablack View Post
What is the normal range of coolant temp for Gen III in summer time.

Took my FJR for a spin and temp out was like 94F and the coolant temp hit 224 at stop lights but then came down to 180s once running..

Any insight?
Normal ^^.

Best thing you can do is go to another screen, anything beside coolant temperature. The wide temperature indications are going to drive you batty. Unlike as is done with Gen2 models, you are seeing actual instantaneous temperature- there is no averaging or buffering to smooth out the numbers. Everything is fine but your temps will change dramatically, as you've seen, making you think something is terribly wrong.
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post #10 of 11 (permalink) Old 07-09-2020, 05:05 PM
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I just asked the wife for tips on a blow job and she just staired at me so I told it looks like I am going to have to give one. She just walked away so I guess I am on my own. Got to go to the gayrage and get the service manual so she understands.

I guess "Burping The Baby" has a different meaning between her and the bike......................

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