Bike running one bar lower on temp gauge

[jpcfjr]

In the last few days my '09 FJR has been at 5 bars on the temp gauge and topping out at 7 bars when idling at red lights. This is one bar lower than normal especially for mid 90's temps. I'm thinking the thermostat is shot but thought I'd ask here before I started replacing things. I've also experienced some stumbling and roughness at higher revs...I'm thinking the computer is thinking the bike isn't heated up and is enriching the mixture.

Anyway, anyone have thoughts or experience with this problem? The bike has 56,350 miles.

Thanks.

 

[Fred W]

My advice? Ignore it. One bar is an insignificant difference.

 

[wfooshee]

If the thermostat were "shot" you'd have one of two things happen.

First, it might be stuck closed. Water never flows through the radiator, and the coolant in the engine itself is never cycled or cooled, and eventually boils. If left like that long enough, pressure will blow something somewhere and spray steam and VERY hot water.

Second, it might be stuck open. Water ALWAYS flows through the radiator, not allowing any temperature buildup at all. he fast-idle at start-up never drops to the warm idle of 1100 RPM, and the temp gauge never gets past a bar, maybe two. (On a Gen-I, you'd probably not even see one bar.)

Since you described neither of these symptoms, don't worry about it.

Abd BTW, references like "lower than normal for July" are irelevant. The engine warms up and the thermostat cycles, regardless of outside temperature. As long as the bike is moving, that is. If it sits running, the fans may have to run longer in hot seasons than in cool to bring the radiator temps down.

 

[ajpagosa]

Mostly agree with other comments here except to note running rich will make it run cooler. 1 bar cooler than normal who knows, other bikes I've had that tended to run lean once that was fixed ran cooler. So if it is stumbling/running rough look into that as a separate issue, which t-stat may be reflecting accurately.

 

[jpcfjr]

By "shot" I mean not working properly...not necessarily not working at all. I think the thermostat is reacting slowly and on it's way out. It is a feedback loop. The fluid gets hotter, the thermostat opens to allow more coolant to flow thus cooling it down and causing the thermostat to close again. If the thermostat reaction is slow, you will get oscillation in the system. I have experienced sluggish reaction in thermostats that are on their way out.

To "not worry about it" is not good advice. Something has changed. Things rarely change for the better on their own especially in mechanical systems. For an engine to run cooler, or appear to run cooler, only two things can have happened. One, the thermostat is now defective, or two, the temperature sensor is malfunctioning and giving a false reading on the dash. Both are distinct possibilities. The easiest thing to check is the sensor because all I need to do is check it with the multi-tester in boiling water and see if it is in spec. I'll probably do that.

I suspect that the most likely scenario, given the number of miles I have put on this bike, is that the thermostat is on the way out.

 

[Fred W]

If you don't want to accept the advice given and think you know better why come on here and ask the question?

 

[wfooshee]

5, 6, 7 bars on a Gen-II is in spec and working. There's nothing to fix.

(Fred's got in before me. Damn!)

EDIT: There could be enough variance between individual parts that a replacement thermostat would behave exactly as what you now see. It's not overheating, and it's not failing to warm up. That makes it OK.

 

[jpcfjr]

It's probably the temperature sensor. I've pulled it and am just about to test it.

I'm not ignoring advice here, but "don't worry about it" is not good advice. This is a safety issue. I ride this bike every day in I95 traffic around DC. Not a place you want to break down. After 56,000 miles in almost 4 years all of the sudden one bar down is the new normal? Not. If you want to ignore something like this on your bike that's certainly your prerogative. I hope you have a good towing plan though.

I was hoping someone had the same experience but so far that doesn't seem to be the case.

 

[ionbeam]

...I'm not ignoring advice here, but "don't worry about it" is not good advice. This is a safety issue....After 56,000 miles in almost 4 years all of the sudden one bar down is the new normal? Not...I hope you have a good towing plan though.
I was hoping someone had the same experience but so far that doesn't seem to be the case.

Not to worry jpcfjr, you aren't the first person to tell us we provide 'not good advice' as they go on to fix something that isn't broken. Getting an indication that your coolant is actually cooler is different from getting an indication that your coolant is running hotter and there is a chance of overheating. FWIW, once the engine is up to operating temperature there is nothing that can make the coolant cooler than what it should be other than the ambient temperature. No matter what your gauge is telling you, your engine and cooling system are working just fine.

 

[jpcfjr]

LOL, wrong. Just tested the sensor and it is reading out of spec. As the temp rises, the resistance goes down. The spec at 176 degrees F is 354 down to 290 ohms. Mine is reading just higher than 354. Thus the ECU thinks the bike is cooler than it actually is. This explains the cooler reading on the dash. However, the fans are still coming on at the appropriate temp but at 7 bars on the dash rather than the "normal" 8. I suspect (but haven't checked yet) that the fan circuit gets a temp reading from somewhere other than the coolant temp reading.

The sensor is bad. Why should I care? The ECU is thinking the bike is cooler than it actually is. Therefore it is dumping more fuel into the cylinders than it should, explaining the rough idle and stumbling I have experienced. Ignoring something like this is not going to make it go away or get better. It will only get worse.

Don't take your own advice.

 

[wfooshee]

Well, that's well and good, but let's check your test just to be sure.......

First, note that with the spec range, the high end of the range is over 20% higher than the low end, so what makes you think this is a highly critical measurement?

Was your temp reading after going past 176 degrees and then letting it cool to that point?

Was the thermometer suspeded in the water, not resting on the base of the pan? (Base of the pan would be hotter than the water within.)

Is your thermometer accurate, and your multimeter?

Lastly, you say it's higher, but you don't give the reading. How much higher? 360 ohms, or 500 ohms?

I'm being a bit of a jerk with all this, I'll admit, but since you're so insistent that something is horribly wrong with your bike and you might die as a result (you did use the word "safety," after all) then let's be thorough and make sure your checks are valid.

So seriously, if the thermometer was resting on the bottom of the pan, or if your multimeter battery is nearly dead, then you don't know crap about your temp sensor being in spec or not.

And finally, you understand that the temp gauge on the dash is not a calibrated laboratory instrument, right?

 

[Fred W]

I repeat, if you think you already know it all, why would you come on here and ask for advice?

 

[ionbeam]

You can go to Diagnostic Code 06 (read on the Meter Assembly) and it will show you the coolant temperature, and it is exactly what the ECU is reading. The diAG procedure is in the FSM and I have a 'how to' here in the Forum.

You would have a legitimate concern if the ECU was thinking the coolant wasn't hot enough to open the thermostat. The thermostat opens between 156 and 163º F and is fully open at 185º. Once the thermostat is open the impact of 15º - 30º temperature variation will have almost no impact on fuel trim. Once the thermostat is open the ECU is satisfied just knowing the engine is at operating temperature. In fact, the ECU will happily let the FJR continue to run even after the coolant temperature sensor indicates the engine has overheated and is boiling over.

 

[jpcfjr]

Thermometer was clipped to the side of the pan, not touching the bottom. Fairly precise thermometer for cooking...can't be totally sure. However, we must take into account the propensity of evidence, trends if you will. The reading on the digital ohmmeter is considered to be true. The thermometer is considered to read accurately. Could these be false? Of course but I have no reason to believe that. The reading I got at 80C was about 360 ohms. Maybe in spec, but, considering the other facts, probably not. The lower temp reading is a MAJOR fact in this case. The poor idling and stumbling is further evidence that something is amiss. I am taking ALL the facts in total and reaching a conclusion. Could I be wrong? Yes. But the probabilities are on my side.

Again the sensor is JUST out of spec or maybe JUST IN spec but the point is it's marginal. It will not get better with time, it will get worse. It's $45 to replace it. WTF, why not? If it solves my problem great. If not, what is $45 to me? Not much. It's not like I'm putting a $3,000 engine in the thing to fix a temp reading.

I have a lot of miles on this bike. I know how it should run. It's not running the way it was two weeks ago. Many people who own bikes put 2,000 miles a year on them and ride them on the weekends. I ride this bike every day of the work week. On a bike used in this manner EVERYTHING is a safety issue. If I stall out on I95 HOV lanes with a jersey wall on one side and cars streaming past in the massive construction zone on the other I'm fucked. Laugh if you want but a poorly running bike is a potentially serious safety issue for me. Ignoring problems and telling people to "don't worry about it" is irresponsible at best.

I posted for two reasons. 1. to see if someone had had a similar issue and 2. to help someone who has a similar issue in the future. I guess I shouldn't have.

I've ordered the part. I'll let you all know if it fixes my non existent problem.

 

[ionbeam]

.. I'll let you all know if it fixes my non existent problem.

Read previous.

 

[SoCalFJR1300]

If you don't want to accept the advice given and think you know better why come on here and ask the question?

Geez man lighten up, he's discussing the problem and thinking about it....doesn't mean he doesn't appreciate others input.

IMOP he's right a change "could" mean a problem developing OR it could be nothing, he just wants to make sure.

 

[LAF]

Well I can see the OP point. My 10 has run at 4 bars since new. Now we all know what our normal bar is at and when we get on it and get stuck in traffic and any other reason we run hot. But as a norm mine runs 4 bars. At 2 years I had it flushed at my shop. When it came back 5 bars was the new normal. I was not pleased. I then cleaned the radiator by spraying Dawn dish soap and peroxide into the fron fins and then running a house from the back. I almost lost lunch when I saw what came out. But no joy still 5 bars. So I redid my flush, burping it as I went, slow fill. Low and behold 4 bars was the new norm. Must have been air?

At any rate I do see the OP point. When you have a norm from new and it changes something has changed.

I do have issues with someone asking for help and then slapping the face that tries to help. So for that I find the OP Guilty as charged.

I do hope he finds his issue but I think the KISS acronym is in play here. I would have cleaned the radiator, tried to burp the system, and probably tried a new radiator cap before I went half cocked on this temp sensor.

And for guys who have been on this Forum since dirt was made, and give help, and tell him they have never seen this part fail, should have been enough for him to look at something else.

I do agree 1 bar is nothing but it has changed so I would want to know. Only problem is what if the gauge just had a fit and likes 5 bars on the same temp instead of 4?

OP wish you luck, but do not bite the hand that holds the master wrench.

 

[Fred W]

The above post supports my original point entirely.

LAF's bike (the same bike as as the OPs) has run at 4 bars since new. The OPs ran at 5 bars since new and is now running at 4 bars. Both bikes are perfectly OK and do not require repair. Sure, if something has changed, keep an eye on it for further changes (if any).

But the idea that the temp reading 1 bar lower on the gauge is causing drive-ability issues is ridiculous. The ECU will not change or adjust the fueling because it thinks the bike is running at 170F instead of 180F. One increment is not significant.

Now if the OP is bored and wants to perform recreational maintenance on his own bike to try and get that magic reading back on the gauge then that is certainly up to him. But calling me (and several of the other more experienced FJR folks on the forum) irresponsible for suggesting he "not worry about it" is an attitude that I just don't have much of a need for.

 

[Top_Speed1]

I read this thread yesterday prior to my ride later...

Mine always ran 4 bars, and last night (90's) it again ran 4 bars but in slower traffic it hit the midway 5 bars until a few minutes of faster speeds. I consider this the norm but if I had a flux of just 1 bar either way? ...as my Italiano bros. would say "fo-ghetta-bow-it!".

I saw a much more difference (temp rise) in my diesel tractor, found several of the core were blocked in the radiator and got her re-cored, changed out thermostat as well. Brought the temp way back down but I saw a much more major flux in that (more equal to probably a 3 or 4 bar rise with the Feej)

Yesterday in the heatwave, I was more thinking... "wonder if I can get air conditioned seats on my next bike?"