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2004 with 48k miles

On a ride today in stop and go traffic and noticed temp up into 230's. 

Stopped for lunch and after heading home temp went up to 251 warning level. Pulled over, shut down and waited a few times and got home. 

Checked and fan is not kicking on.

Checked fuse and it's good.

Checked coolant level (slightly low, maybe 1/2 cup)  and burped. 

Idled it again and at 225 no fan. Got to 233 then I shut off. 

 

Help?

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If the fuse is good then the issue is either with the wiring, the fan switch, or the fan motor.  The fan switch is in the left radiator. With the ignition on and a good fuse there should be power to the switch. Make sure the contact with the switch is clean. If you run a jumper from the switch lead to ground the fan should start. If the fan does not start then check voltage. If voltage is good and the fan does not start then the fan may be bad. If the fan starts then the switch may be bad. 

 

Whichever component seems to be bad make sure you check it carefully before you order a new part. A corroded electrical connection can make any any component seem faulty.

 

Good Luck

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MarkDetroit thanks for the reply. 

Couple things:

Ugh shit I don't know how to check what you're suggesting! I'll find someone to give me some wisdom. 

In your opinion then the thermostat is not the issue? 

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As said before, the temperature switch is in the left side radiator.  It is a goldish metal nut looking thing with a single wire coming out of it on the bottom of the radiator.

 

If you want to check the switch, unplug the single wire from the back side of it and use a paper clip or some other conductive item to short the wire to ground (the frame or engine case works fine).  It doesn't matter what temperature the bike is, just as long as the ignition is on.  I'd have to consult a wiring diagram, but the engine may have to be running.

 

Under normal conditions, everything up to this point is provided with battery voltage.  When the temperature crosses a certain threshold, the switch will provide ground to complete the circuit.  Only one wire goes in because the radiator itself is the other "wire" as the radiator is grounded. 

 

If the fan does not turn on at this point, then we have narrowed the fault down to the fan itself or the wiring connected to it.  While the wire from the thermostat is removed from the temp switch, use a volt meter to measure the voltage between this wire and ground.  Your should see about 13v on the meter.  If you see zero then keep working your way up the wire until you get to the fuse box until you see 13v.  Once you find 13v, then you will have identified the region where the fault occurred.

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If the engine is getting hot and the radiators themselves are getting hot then coolant is flowing and the fan needs to come on. So you need to solve that problem.  

If your thermostat fails in a closed condition that will affect coolant flow to the radiators and they wont get very hot before the temp gauge gets to a very high temp.  (Luckily thermostats usually will fail in an open condition.)  If it seems the radiators are not getting very hot then the other possibility is a bad water pump.

In any case it's easy to check the function of the fan with my suggestions above. Hopefully the problem is just a corroded or loose wire or a bad switch. Those are easy fixes.

Also make sure you check for radiator fill condition at the radiator cap and not at the overflow tank.  

And you may already know this but the temp that is shown on the dash gauge is for the coolant in the front cylinder head and is not the temp of the coolant in the radiator. The switch for the fan is in the radiator. You can look in the service manual to see the temp range that the fan switch should activate but that's not what you are reading on the dash gauge.

 

 

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True, those are valid points as well.  There may be a mechanical issue with the bike causing a lack of coolant flow to the radiator. 

 

If the previously mentioned trick does cause the fan to kick on, then you must determine if the issue is related to the temp switch or coolant flow to the radiator.

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Phew, ok thanks all! I'll be checking tomorrow and will update 

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Forum people!

So a buddy FaceTime walked me through checking the fan switch. Turned ignition on (but engine not started), unplugged the lead cable, stuck in a paper clip, touched other end to radiator and boom, fan turned on!

IF there's a dirty/corrosion issue with the switch, what do I use to clean it properly? 

And another dumb one, if I'm cleaning it with some type of liquid chemical, what precautions do I need to take so I don't f*ck this up even more? 

 

Thanks all!

Wayne

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Wayne, What you checked with your test today was the fan. And now you know it works. That's great.

Possibly the switch is ok, but you don't know that yet.

Clean the contacts with sand paper, contact cleaner, or similar. I use Deoxit. Then make sure the cable fitting is tight to the switch fitting.  I would then idle the bike to heat it up. Make sure the radiator is topped off and the radiator cap is tight!  Check the radiators as the bike is idling to make sure they are warming up.  By the time the display temp is up to about 225F, or so, the fan should turn on and the radiators should be hot!  If, at that point, everything is hot and the fan has not come on then the switch may be bad.  You can remove the switch and test it in a pot of boiling water.  The switch should close at between 208 and 216F.  You may need to boil antifreeze to get above 216F if the switch doesn't close at 212F (boiling H2O).  It is then supposed to open back up at between 199 and 207F. (I got these #'s from the service manual)

If the radiators don't get hot when the gauge temp is about 225F then you may have a stuck closed thermostat or bad pump or....

 

Good Luck

 

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Mark,

Thanks again for the info.

I'll clean the contacts per your suggestion and we'll see. Fingers crossed...

 

Wayne

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You don't have to boil antifreeze, and probably don't want to.  Instead saturated salt water @ approximately 23% by weight, boils at around 227 degrees at sea level.  If you do 1 part salt added to 3x the weight of the salt as water, you will have about the right amount without wasting salt.  All of the salt does not need to dissolve.

 

I would definitely not advise checking the temperature of the coolant by removing the radiator cap and checking directly.  The boiling point of the coolant is elevated under pressure, meaning that releasing this pressure can spontaneously cause all of your coolant to boil, leading to a rocket of coolant that can cause 3rd degree burns.

 

 

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12 hours ago, MadScientist said:

You don't have to boil antifreeze, and probably don't want to.  Instead saturated salt water @ approximately 23% by weight, boils at around 227 degrees at sea level.  If you do 1 part salt added to 3x the weight of the salt as water, you will have about the right amount without wasting salt.  All of the salt does not need to dissolve.

 

 

 

Salt is a great idea to elevate water temp to approach the switching temp of 216!  And a bonus - you can do it while your wife is home - LOL.

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You may only have air trapped where the thermoswitch screws into the radiator.

 

Download the service manual if you haven't already and perform the air purging protocol.

 

There are probably videos on YouTube which take you through this and all the other checks, tips and tricks mentioned above.

 

One tip I will mention is tapping the edge of the radiator with a rubber mallet when purging or even just with the bike warmed up close to fan operating temp... Might dislodge any trapped air / bubbles.

 

Air around that thermoswitch means it just isn't getting a proper read on the coolant temperature as it is not properly immersed in said coolant.

 

 

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On 5/19/2017 at 4:02 AM, MarkDetroit said:

Salt is a great idea to elevate water temp to approach the switching temp of 216!  And a bonus - you can do it while your wife is home - LOL.

 Or use some vegetable oil and cook up some chips when you are done. It would be a good idea to clean the switch of any residual coolant before you do that, but ethylene glycol is not THAT toxic. Actually, it is less toxic than table salt (but a lot easier to ingest in large quantities).

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Ugh...

Cleaned the contacts and fan did not start when attached to the switch.

Bought a new switch, installed and ran engine - still no fan.

Once it cools down I'll do another fill/burp. 

 

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I burped/filled the system - nada, no fan.

I actually did the thing where I used a paper clip to start the fan - fan started.

I've read to try a new radiator cap...

 

Any other thoughts???????

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Hmmm one thought is do I need to clean the fan cable end as well?

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2 minutes ago, Phongeer said:

Hmmm one thought is do I need to clean the fan cable end as well?

Well, this is a bummer.

If the fan starts when you use a paper clip on the switch lead then it should start when connected to the switch.  No reason not to check and clean all connections but that's probably not the problem.

I know it's hard to judge but does the left radiator seem to be getting hot as the engine warms up? How hot is the display showing?

The radiator cap has to be tight just like in a car. It rotates till it comes to a solid stop.

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The left radiator gets HOT! I checked a couple times. 

I've fussed with the radiator cap. Trying to figure out how to purchase one. I thought I could at my local (around the block) O'Reilly's but they don't seem to be able to figure out a cap for my moto...

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15 minutes ago, Phongeer said:

The left radiator gets HOT! I checked a couple times. 

I've fussed with the radiator cap. Trying to figure out how to purchase one. I thought I could at my local (around the block) O'Reilly's but they don't seem to be able to figure out a cap for my moto...

It's a good sign that the radiator is hot! That should mean the pump is working and the thermostat is opening.

So you have the old switch out of the bike. You can check to see if it is good or not if you are able to check continuity - like with a digital volt meter. Do you have a volt meter? By 216 F there should be continuity. Maybe both switches are bad (LOL - i doubt it - but it's good to check.)

And the other thing is that the left radiator has to be grounded to make the switch circuit work. I don't recall if there is a ground wire attached to it or what... Likely someone else on this forum wil know without me going to look on the bike.  But you need to make sure it's grounded. (Maybe the issue is that the ground wire or connection is loose or something.)

 

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When you used the paperclip to check the fan did you touch it to the radiator or some other point on the bike?

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I touched it to the radiator. Should I touch it to somewhere else? 

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26 minutes ago, Phongeer said:

I touched it to the radiator. Should I touch it to somewhere else? 

No - you did it right.

If the ground lead to the radiator was broken then the fan would not have started...

 

So, I guess I would try and test the switches... At least the old one.

It is an option to run a manual switch to the fan to see if the running fan can properly control the operating temps. But then you still will need to figure out why the fan is not starting.  I need to think about this a bit more.

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Mark,

First, thanks for all your help!

So a buddy and I just talked on the phone. He's a former Honda shop mechanic and race mechanic. I reviewed it all with him and he thinks there's still air in the system. He believes that since the temp got up to 250 a couple times that the boiling created more air pockets. 

Thoghts?

Anyone with magic concerning getting "all" the air out?

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On 17 January 2016 at 10:03 AM, Marooncobra said:

Mate,

Get yourself a spill free coolant funnel ( see photo) and connect using the correct cap which comes with the kit. You can then fill the bike with coolant and run it up watching all of the air come out through the funnel. As the coolant gets warm it will rise in the funnel, air will come out as large bubbles and then as small almost fizzy bubbles as the thermostat opens and all of the air is released. You will see the level of coolant in the funnel drop slightly as the thermostat opens. I run the bike like this mainly at idle but every so often I find if you turn the bike off, air is released as the flow has stopped. Restart the bike and idle again and continue until all air has been released. It can take a while and at times you will feel that you have a leaking head gasket as towards the end you get loads of really small fizzy air coming out. It does stop eventually. You can then let the bike cool completely, with funnel still connected, that will allow all of the coolant that is still in the funnel to fill the system as the water cools.

Once totally cooled take the bike off the side stand and lean the bike right over, with the funnel at the highest point, to ensure all of the air has come out of the second radiator as the front hose that connects the two radiators is not a straight hose and air collects in there as well as the top second radiator where the thermo switch is to operate the fan. Once done, remove and fit your radiator cap. Job done.

post-32093-0-42415400-1452984444.jpeg

 

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