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Intermittant High Coolant Temperature Or Just Faulty Readout?


joel1952

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Looking for some quick, expert help. I'm in Iceland, so I haven't had time to search the forums,

Anyone with SPECIFIC EXPERIENCE or KNOWLEDGE please reply

I had an overheating incident, did some roadside, testing and road another 200miles with no problem...

MY QUESTION

"How can I tell if the coolant is actually overheating, or if the temperature readout is faulty??"

i.e. Is this an intermittant overheating problem or not???

FYI 1999 year bike. I purchased this bike with 50,000 miles in 2012, so I do not know if the thermostat was ever replaced. I now have 61,000 miles

THIS IS WHAT HAPPENED

ambient 10C/ 50F, Traveling at speed on a country road. Stopped and idled for less than one minute and got back on the road. Coolant temperature went up to 122C/250F, so I stopped after 2 minutes, but there were no overheating symptoms

I checked the coolant in the reservior. I had filled it about half way 2000 miles earlier, but it was now full

No coolant overflowed

(would the overflow actually come out of the radiator cap??

or would the overflow come out of the reservior?

the reservior, I think!?!?)

Coolant in reservior was warm, not hot.

Fans were not on

I checked the fuses. I am not sure which one is for the fans, but all the fuses are in the box by the battery, CORRECT??

I let it cool down and started it and it over-heated up again

I thought maybe the temperature readout was wrong, so I got back on the road. It exceeded 122C again, but mostly was 80C

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My buddy had a temp issue he chased for a long time. He eventually decided it was not really the coolant and took off the front fairing to look at the gauge connections. He found one of the wire holder tabs was touching the printed circuit board and causing false readings.

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If you had boilover into the resevoir, it overheated.

If the fan didn't come on at all, THERE IS YOUR PROBLEM.

I'd also replace the radiator cap at this point. Cheap insurance.

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If your coolant level is too low the fan will not come on regardless of temperature. Ask me how I know...

On the 5th gen not the 6th gen.

Roll On ,,,

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Have you ever changed the antifreeze in it since you bought it? If not I'd start there. Once it's all drained disconnect the radiator hose from the water pump. Then you can take a garden hose and flush it from the hose and also from the fill on the right hand side radiator. Then re-fill with 3 quarts of coolant.

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It doesn't sound like it is actually overheating. I think it an issue with gauge. I'd be pulling the front fairing off & get a look at the wires & the printed circuit board. I'm amazed that Honda left it completely exposed with no cover over it.

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I just replaced my rad cap with a $7.49 cap from auto parts store, fits a 1998 Mitsubishi eclipse.

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It doesn't sound like it is actually overheating. I think it an issue with gauge. I'd be pulling the front fairing off & get a look at the wires & the printed circuit board. I'm amazed that Honda left it completely exposed with no cover over it.

thanks for answering the 2nd half of the question, you get full credit ;-)

Why do Icelanders have less time to do searches?

I don't know about Icelanders, but being from Los Angeles on the VFR I keep in London, on the road 10+ hours a day, in remote areas with poor internet connections, I just wonder about people that respond to important questions without trying to help

My buddy had a temp issue he chased for a long time. He eventually decided it was not really the coolant and took off the front fairing to look at the gauge connections. He found one of the wire holder tabs was touching the printed circuit board and causing false readings.

Yeah. Seems likely, as the problem only occurred that one afternoon on and off.

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If you had boilover into the resevoir, it overheated.

-- I thought that. But the reservoir coolant was tepid

If the fan didn't come on at all, THERE IS YOUR PROBLEM.

-- Not if the the coolant isn't actually hot enough

I'd also replace the radiator cap at this point. Cheap insurance.

-- Insurance for what?

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There is a wire connection to the fan themo switch on top of the right side rad. Could be the left? I don't remember which rad at the moment. In any case, unhook the wire and then turn on the key. Using gloves touch the wire to the bare rad and ground it so that the fan should come on. If not bad fan circuit. If it does spin up then the thermo switch is probably bad.

Sent from my SM-N900V using Tapatalk

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There is a wire connection to the fan themo switch on top of the right side rad. Could be the left? I don't remember which rad at the moment. In any case, unhook the wire and then turn on the key. Using gloves touch the wire to the bare rad and ground it so that the fan should come on. If not bad fan circuit. If it does spin up then the thermo switch is probably bad.

Sent from my SM-N900V using Tapatalk

Sitting on the bike, the fan switch is on the left-hand radiator.

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Like kevCarver said, I chased exactly that problem for months. It would read normal, then peg and usually stay there. After replacing the sending unit (deep in the V), verifying the fan op several times, and burping the rad's too many times I was stumped. It wasn't until the fuel gauge started mis-behaving that I got serious about looking for a short.

I started chasing wires starting with the instrument panel. It didn't take long to get to the wiring bundle. Turns out the culprit was indeed a wire hold-off bracket behind the headlights. Mine was bent out and touching the circuit board. It was in contact with the circuits for (wait for it) the temp and fuel gauges. I bent it back where it should have been, swore a little for the many man-hours wasted on all the other stuff I was certain it must have been, and haven't had a problem since.

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There is a wire connection to the fan themo switch on top of the right side rad. Could be the left? I don't remember which rad at the moment. In any case, unhook the wire and then turn on the key. Using gloves touch the wire to the bare rad and ground it so that the fan should come on. If not bad fan circuit. If it does spin up then the thermo switch is probably bad.

Sent from my SM-N900V using Tapatalk

That's the kind of test one needs to diagnose this problem. THANKS.

And fan should come on at 215-degrees F, so if you were showing 250 it should have definitely been whirring away.

No. Not if it was NOT actually overheating.

I've indicated that it probably is NOT actually overheating. That is my question...How to tell if it is actually overheating...short of buying a $300 infared remote thermometer as one poster suggested :goofy:

70232959_large.jpg

Works every time .

Roll On ..

Thermal Imagers >>

100418.jpgIR Thermometer

Point it at the upper rad hose .

Use IR themometer to check to see if the sending unit is bad .

Roll On ...

I'm assuming you are joking.

One would actually have to TEST the sensor, to see if the sensor is sending the wrong signal at the wrong temperature.

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There is a wire connection to the fan themo switch on top of the right side rad. Could be the left? I don't remember which rad at the moment. In any case, unhook the wire and then turn on the key. Using gloves touch the wire to the bare rad and ground it so that the fan should come on. If not bad fan circuit. If it does spin up then the thermo switch is probably bad.

Sent from my SM-N900V using Tapatalk

That's the kind of test one needs to diagnose this problem. THANKS.

And fan should come on at 215-degrees F, so if you were showing 250 it should have definitely been whirring away.

No. Not if it was NOT actually overheating.

I've indicated that it probably is NOT actually overheating. That is my question...How to tell if it is actually overheating...short of buying a $300 infared remote thermometer as one poster suggested :goofy:

Works every time .

Roll On ..

Thermal Imagers >>

100418.jpgIR Thermometer

Point it at the upper rad hose .

Use IR themometer to check to see if the sending unit is bad .

Roll On ...

I'm assuming you are joking.

One would actually have to TEST the sensor, to see if the sensor is sending the wrong signal at the wrong temperature.

So how would you check the sensor ? Check for resistance ? and compare to a chart for the correct reading at certain temp. BUT I would first confirm the sending unit actually malfunctioning. Or you can just stand back and throw cash at it

Roll On ..

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Like kevCarver said, I chased exactly that problem for months. It would read normal, then peg and usually stay there. After replacing the sending unit (deep in the V), verifying the fan op several times, and burping the rad's too many times I was stumped. It wasn't until the fuel gauge started mis-behaving that I got serious about looking for a short.

I started chasing wires starting with the instrument panel. It didn't take long to get to the wiring bundle. Turns out the culprit was indeed a wire hold-off bracket behind the headlights. Mine was bent out and touching the circuit board. It was in contact with the circuits for (wait for it) the temp and fuel gauges. I bent it back where it should have been, swore a little for the many man-hours wasted on all the other stuff I was certain it must have been, and haven't had a problem since.

You and kevCarver must be right.

Since that incident, I was on a 4x4 road, going slow, the temp hit 102C and the fans came on and the temperature went right down.

i.e. MY READOUT IS INCORRECT (intermittantly), thus the fan did not come on.

Cudos!!!!!!!!!!!

If you had boilover into the resevoir, it overheated.

-- I thought that. But the reservoir coolant was tepid

If the fan didn't come on at all, THERE IS YOUR PROBLEM.

-- Not if the the coolant isn't actually hot enough

I'd also replace the radiator cap at this point. Cheap insurance.

-- Insurance for what?

More information in response to your most unhelpful post

Re: Coolant level increase

What is commonly called a coolant reservior is actually and EXPANSION tank. When coolant volume expands with temperature, the hydraulic pressure is vented into the tank. Hydraulic pressure can be 100's, even 1000's of PSI. Do you understand that concept?

furthermore, when the coolant in the engine cools, it contracts and the syphon action sucks it ( like your post) back into the engine. :mellow::wink:

Re: the fan is the problem

If the sensor doesn't sensor an overheating temperature, of couse the fan DOES NOT come on. I gave you information indicating that the expansion tank was tepid and the fan fuse was ok, yet you go down the wrong road.

Re: Replace the radiator cap

  1. If it ain't broke, don't fix it. Radiator caps are not a preventative maintenance item.
  2. Do you know why auto parts have a 90 day warranty? "because that is when they break". What kind of "cheap insurance" is that. That's just another potential problem. Radiator caps are a simple, reliable technology. (they still don't make digital radiator caps, They could)
  3. THE ONLY REASON TO REPLACE THE RADIATOR CAP WOULD BE IF YOU BOUGHT A NEW RADIATOR AND WANTED A NEW CAP TO MATCH!!

(I'm getting close to the end of my Radiator cap rant... :cheerleader: )

4. I forgot my fourth point . HA

There is a wire connection to the fan themo switch on top of the right side rad. Could be the left? I don't remember which rad at the moment. In any case, unhook the wire and then turn on the key. Using gloves touch the wire to the bare rad and ground it so that the fan should come on. If not bad fan circuit. If it does spin up then the thermo switch is probably bad.

Sent from my SM-N900V using Tapatalk

That's the kind of test one needs to diagnose this problem. THANKS.

And fan should come on at 215-degrees F, so if you were showing 250 it should have definitely been whirring away.

No. Not if it was NOT actually overheating.

I've indicated that it probably is NOT actually overheating. That is my question...How to tell if it is actually overheating...short of buying a $300 infared remote thermometer as one poster suggested :goofy:

70232959_large.jpg

Works every time .

Roll On ..

Thermal Imagers >>

100418.jpgIR Thermometer

Point it at the upper rad hose .

Use IR themometer to check to see if the sending unit is bad .

Roll On ...

I'm assuming you are joking.

One would actually have to TEST the sensor, to see if the sensor is sending the wrong signal at the wrong temperature.

No not joking first I would check with IR Thermometer TO SEE IF THE BIKE IS REALLY HOT or you can just stand back and throw money at it until you fix it.

Roll On ..

Yeah, well, I figured it wasn't that hot. It wasn't clicking and steaming. ;-)

And like I said, I am in Iceland. The local auto parts and high-tech auto mechanic was 400 miles away

Make no mistake. I wasn't going to spend money and hope the problem would go away.

Even buying a radiator cap for $15 was the dumb idea that a couple guys posted, since the cap has nothing to do with overheating. AND I HATE RANDOM PART REPLACERS like them.

AND WHAT IS WITH THE GUY THAT ASKED HOW OLD MY COOLANT IS? Old coolant, new coolant, plain water, they all get to the same temperature at the same operating conditions, give or take a few degrees.

I just replaced my rad cap with a $7.49 cap from auto parts store, fits a 1998 Mitsubishi eclipse.

Why did you replace it?

Before I went 200 miles out of my way, shopping for a 1998 Mitsubishi radiator cap, I rode 500 miles and passed 200 cars. Hmmmm. only 2 mitsubishi's in the whole country. And both of those had Danish and German plates. They don't import Mitsubishi's to Iceland. HA

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After rereading your first post I see you did mention living in Iceland.

'I've indicated that it probably is NOT actually overheating. That is my question...How to tell if it is actually overheating...short of buying a $300 infared remote thermometer as one poster suggested :goofy:'

There price here is $25 for cheap one that works great. . I can see why dont want to purchase one if they are $300..

Roll On ..

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You can get very affordable IR thermometers. I got this one from Amazon for $15. Not a typo..

51-JNUrXILL.jpg

They can be useful as crude tuning devices too. I diagnosed an intermittent misfire on my car, as one cylinder's exhaust port wasn't getting as hot as the rest.

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"....So how would you check the sensor ? Check for resistance ? and compare to a chart for the correct reading at certain temp. BUT I would first confirm the sending unit actually malfunctioning. Or you can just stand back and throw cash at it "


I love your tag line, "...or you can just stand back and throw cash at it", I would add, "and waste time".


If I had 1) "burped", 2) replaced coolant, 3) gone 100's of miles and out of my way to purchase a radiator cap...

I would have been no closer to solving the problem and I would have wasted DAYS when I could have been riding.


TO ANSWER YOUR QUESTION.

First, It SHOULD BE EMPHASIZED that the problem is the READOUT, NOT the coolant temperature SENSOR in my case

Second, You know as much as me. I don't know the POO (Principle of Operation) of the sensor. Easiest ("ease" is relative of course) way would be remove the sensor, use extension wiring and put it in a hot pot of water. (which is similar to what I did with my "NON-defective thermostat" AFTER I REPLACED IT :unsure: )
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After rereading your first post I see you did mention living in Iceland.

'I've indicated that it probably is NOT actually overheating. That is my question...How to tell if it is actually overheating...short of buying a $300 infared remote thermometer as one poster suggested :goofy:'

There price here is $25 for cheap one that works great. . I can see why dont want to purchase one if they are $300..

Roll On ..

$25?? When I said "$300", my brain was stuck in the 1990's when that technology was new. That would be a good tool to have. But under my current circumstances, not attainable.

Sorry. I said, "...in Iceland" The internet being what it is, I was talking shorthand...

  1. I live in Los Angeles
  2. My VFR lives in London
  3. I'm on a 2 month trip...
  4. ...centered around 3 weeks in Iceland and the Faroe Islands

NON-TOPIC RELATED...

Amazing trip. Colder than anticipated. A little drier than anticipated. MUCH WINDIER (windy-er) than I even considered.

Snowing at Sea Level when I arrived in Iceland on the Ferry

Snow and ICE!!!!!!! just 10 short minutes after leaving the Ferry Port

NO ONE TOLD ME THERE WAS A MOUNTAIN PASS RIGHT OUTSIDE OF THE PORT. And even if they did, I would think "It's Spring time, No Problem"

I would fire my Tour Guide. But he is me. :comp13:

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