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No fan...


Phongeer

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Ok latest in this saga...

Bought the spill proof funnel and ran the "cycle" twice -- set it up, ran moto, revved a few times, tipped to the left.

Going to do one more cycle but so far no fan turn on

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Bike must be on sidestand during entire purging procedure. Not sure if you just tipped it at the end or not.

 

I have found I have needed to protect all wiring and connectors near right radiator spout and let it spew a bit with some good blips of throttle, once the temp is up to where the thermostat (not thermoswitch) should be fully open, then cut ignition. Let it cool with cap off, refill radiator and overflow bottle. Of course going too far with it can lead to more air getting in so it's a fussy business. Careful not to burn yourself.

 

I'm convinced it's air trapped around the thermoswitch.

 

You've demonstrated the fan and wiring are OK.

 

You've installed a new switch (unless it's bad from the factory, improbable but not impossible).

 

Have you tried my suggestion of banging the radiator to dislodge any air when it's up to fan operating temp? This is once cap is back on as at that temp, otherwise, it would overflow.

 

Also bang radiator while doing purging procedure.

 

Frustrating

 

Edit: I see you have spill proof funnel.

 

 

 

 

 

 

 

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2 hours ago, Phongeer said:

Ok latest in this saga...

Bought the spill proof funnel and ran the "cycle" twice -- set it up, ran moto, revved a few times, tipped to the left.

Going to do one more cycle but so far no fan turn on

 

When you did this did much air come out of the system? As mentioned in my procedure you have to let the bike cycle through the thermostat opening fully. Once cool the water level would have dropped in the funnel and this is when I tip the bike fully over to the left. Almost so the fairing is 5 inches from the floor to ensure that pocket of air, that can trap in the top of the radiator, can be burped out across the cross over radiator hose and out of the filler point. If after this you still don't get the fan operating I would suggest you have either a faulty switch or an electrical issue with the circuit.

 

I have fitted a Davis Crag digital fan switch http://daviescraig.com.au/product/digital-thermatic-switch-kit-12-24v-0444/digital-thermatic-switch-kit-12-24v-0444 which allows me to adjust the temp the fan can operate so the OEM fan switch is now redundant. I have mine switching on when the temp in the first radiator hits 95 degrees centigrade.

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My Honda shop/race mechanic friend walked me through the burping scenario. After doing the no spill coolant funnel and running a few cycles I went for a ride on the highway. I realized the problem is not the fan...

Normally on the highway my temp stays around 180'ish. Yesterday (and a couple Sundays ago when this all surfaced) the temp raced right past 180. And the fan did not start. 

We believe there's an issue with the thermostat. Or maybe the water pump. Thoughts? 

Both radiators feel hot to the touch and the hose from the top of one radiator to the other is hot to the touch. Could this be coming from the heat of the engine itself? 

I'm thinking I'm ready to take it into the real shop...

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Sounds like thermostat is working and pump is working if both radiators are hot after 78-80 degrees C as this is when the thermostat opens and allows the pump to circulate the coolant around the system. You can test this by starting the bike from cold and watch the temp gauge whilst touching the radiator with the fan switch in. It should remain cold until the thermostat opens at between 78-80 degrees C. On opening initially you will see the temp drop again as that cold slug of initial water from the radiators cools the engine slightly. if this occurs then both the thermostat and pump are working. If you have burped all of the air out of the system it suggests you have some electrical issue as you have said both radiators are hot after running the bike for a period. If you have an OEM switch fitted in the radiator then the fan should be switching the fan on around 102 degrees C

 

 

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If you had access to an IR thermometer, you could measure the radiator temperature near the thermoswitch, that would allow you to confirm whether that area was above the switching temperature.

 

When you installed the thermoswitch, have you used a thread tape or other insulating material that might be preventing the switch from forming part of the path to ground? You could check continuity from the switch body to the radiator or back to the green wire in the 2P connector for the radiator fan. If there's no continuity here, it won't matter if the switch works or not.

 

Personally I'm not a big believer in the desperate need to burp these systems; by design, they have some good air displacement systems in place, and I've never done more than fill the system one the sidestand, waggle the bike around a bit, start the engine and blip the throttle a few times before topping off and fitting the cap Same applies to my VTR1000F which uses the same radiator setup.

 

If your bike normally runs around 180F then your thermostat is probably OK. The other check is to start the bike from cold, and keep a hand on the right radiator. If it stays cold for a few minutes then suddenly gets too hot to touch, then the thermostat is OK. If it slowly heats up from the time the bike starts, it is stuck open.

 

I would also suggest confirming the radiator cap is holding pressure properly, a symptom of a fault is bubbling through the reservoir when the bike is over 235F.

 

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Thanks again for all the help and wisdom.

 

Want to clarify though: 

Normally my temp stays at around 180 degrees when on the highway. The last two times I've ridden at highway speeds, the temp did NOT linger at 180 but went all the way to 250 and the warning light came on.  

And both times the fan did not kick on at 225. 

 

Thoughts???

 

 

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Back to the thermostat I would think, it might be jammed shut, and will prevent/slow coolant from getting out to the radiators, hence they won't be getting as hot as the engine and the thermoswitch won't trigger the fan. Pulling the thermostat out requires removal of the throttle bodies and associated hoses, a no-fun job that you won't be in a hurry to repeat. If you can borrow or buy an IR thermometer  (e.g. like this http://www.ebay.com/itm/DT8260-Non-Contact-LCD-Digital-IR-Laser-Infrared-Thermometer-Temperature-Gun-/332234976254?hash=item4d5abf6bfe:g:YKkAAOSw~OdVWuHN) you can read the radiator temperature directly and see if it is close to the engine temp, if the rads are much lower that would point to the thermostat being closed.

 

I've also read one instance where the drive coupling to the pump had sheared and gave a similar result (no coolant being pumped to the radiators), but I think that is a very isolated case.

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This is a challenging problem. It certainly seems as though the fan switch is not the problem. But before I pull the thermostat I would make sure the switch does work by testing it out of the bike (in the kitchen). And then I would take the pump apart to make sure the impeller or drive coupling are not damaged or free spinning. Those are the easy things.

Then possibly the problem is the ECT sensor (engine coolant temp sensor) that sends the coolant temp signal to the dash and ECU.  Maybe the engine is not getting excessively hot at all but the ECT is sending bogus info...  Unfortunately you have to pull the throttle bodies to remove the ECT sensor from the head to test it. So when you do the thermostat, and if it doesn't look or test bad, make sure you check the ECT before putting it all back together.

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I really don't see how the thermostat has anything to do with the fan not working. They are two independent phenomena. I do understand that hot coolant must be flowing past/around the thermoswitch for it to turn on, but the op seems to have confirmed the left radiator gets hot.

 

If the water pump weren't working he would have other symptoms of overheating in extremis as well as late or no actuation of the fan. He didn't mention that.

 

When burping with the cap off, you can see the coolant flowing according to revs, thus confirming the pump is working and thermostat is open.

 

It keeps coming back to your fan not turning on when the temp reading on your gauge cluster says it should.

 

I would primarily suspect an issue with the fan and/or its associated wiring.

 

At a long shot it could be as someone mentioned, that the reading displayed on your instrument panel (gauge cluster) is erroneous misleading you to think the fan should be on when it shouldn't, though I seriously doubt this. Still, if you wanted to check out that possibility, it is possible to check all the associated wiring without removing the airbox and throttle body, but yes, to check the sensor itself you would have to dig in to the sensor itself on the back of the front cylinder block (in the V of the motor). I sincerely think this would be barking up the wrong tree.

 

You may have an intermittent fault in either the fan wiring or the fan itself. These intermittent faults are a royal PITA. Almost impossible to reproduce so as to pinpoint the exact location of the fault. Often they only raise their head in certain circumstances, such as when hot, or due to vibrations or wires moving in the wind when in motion. This is particularly pertinent when checking the fan operates by ground directly and bypassing the thermoswitch with a paperclip or wire, as we tend to do this when the bike is cold, so as not to burn ourselves, but thus not factoring in heat-provoked faults.

 

Unfortunately, often the most effective way of remedying such faults is to replace parts. This should always be done one by one if you really want to know which part is to blame. If you have just had enough and want it fixed you can replace all suspect parts and swallow the cost.

 

I understand you have already replaced the thermoswitch, so unless by freak chance you got a faulty one off the shelf, that item should now be ruled out as the culprit.

 

Perhaps replace the wiring in case there is a small crack or other imperfection unseen to the naked eye. Then replace the fan which might just be on its way out, occasionally and intermittently behaving or misbehaving. I would suspect the wiring first.

 

I also don't see what the radiator cap has to do with fan operation. You report both radiators are heating up. I assume too hot to touch after a while. I guess if the cap is faulty it could be letting air in but you would also have the issue of the coolant boiling and the overflow tube spewing coolant onto the ground, which you have not mentioned.

 

Otherwise you just have a stubborn bubble at the thermoswitch location and will have to get creative with dislodging it.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Both radiators feel hot to the touch and the hose from the top of one radiator to the other is hot to the touch. Could this be coming from the heat of the engine itself? 


How hot? Too hot to keep your hand on the hose? Touching left radiator would burn?

If so, I doubt it's the thermostat or the pump. That level of heat won't be from the "heat of the engine" as you say. Which I take as meaning from the heat irradiating from the engine and heating the hose via the air.
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The Engine Coolant Temperature (ECT) sensor is found on the rearward face of the front cylinder block, in the V of the engine. It's a double whammy in that it has two thermistors (electrical resistors whose resistance is greatly reduced by heating, used for measurement and control): one provides coolant temp data to the ECU and the other sends the data to the display panel. Usually when something goes amiss with this system you would probably get intermittent low readings or no reading at all, or it might fluctuate wildly. Rarely would it show greater values but it isn't impossible. The sensor itself could be bad, but it could also be the display panel/gauge cluster whatever you want to call it. It could also be a connector or a wire.

 

If the bike is running ok, not running too rich or too lean, coughing, spluttering, major fuelling type issues, excessive fuel consumption,you get my drift: not running rough but smooth and as per usual, and above all, the extra set of valves come into play in VTEC mode (above 6800 rpm for 2002-2005 and above 6400 for 2006-on), then we can assume the part of the sensor providing data for the ECU is OK. Remember for VTEC to function, the ECU is programmed in such a way that certain parameters must be met and besides RPM, another is engine temp (64*C from which a certain oil pressure is assumed to actuate the VTEC system).

 

A quick way to check this is by removing the left side fairing, a bunch of cables should be seen coming out from the engine, under the frame. There should be a round shaped connector, between the left hand side radiator and the frame. The Yellow/Blue and Green/Orange cables send data to the ECU and the Green/Blue and Green (ground) go to the Display. If you place a 1K resistor in parallel on the display line and the Display shows 50-70*C, then the Display Panel/Gauge Cluster is OK. By default, the problem would lie in the sensor or the connector of that line. If, with the resistor in place, the display is still showing obviously erroneous temperatures, the problem would most probably lie in the Display Panel itself, or anywhere between where you placed the resistor and the panel (including the panel).

 

Don't forget the famous yellow (orange on 5th gens and 6th gens from 2006-on)shite quality common ground bus connector. If it's bad, as they usually are, even from factory, just a really bad design and which many of us here on VFRD can't encourage people enough to apply a fix to, if it's bad, then any and every electrical system involved with the front subharness can go haywire.

 

Yet I digress... I really don't think it's your temp sensor.

 

Sudden rising temps and a fan which won't come on usually means air in the system once the directly related elctricals have been ruled out.

 

 

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On 5/29/2017 at 1:45 AM, Phongeer said:

Thanks again for all the help and wisdom.

 

Want to clarify though: 

Normally my temp stays at around 180 degrees when on the highway. The last two times I've ridden at highway speeds, the temp did NOT linger at 180 but went all the way to 250 and the warning light came on.  

And both times the fan did not kick on at 225. 

 

Thoughts???

 

 

Phong, Please let us know what you have found. We all need the education!

Thanks

 

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  • 2 weeks later...

Update 6/22/17:

Took the bike to a local dealership we have a bit of a connection to, Century Cycles in San Pedro. Great folks there, especially owner Tim. 

They changed out the fan motor, switch and themostat. Picking up in the next day or two. 

Can't wait to have it back! We have a couple trips coming up in July; a possible ride up the coast to Oregon and the Sierra Stakeout camping trip. 

 

Thanks again to you all for your wisdom. I love this forum!

 

Wayne

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Ah, according to the shop, all three items were the culprit. 

They said they couldn't get the fan to work at all. 

And for sure they saw the thermostat was stuck. 

Sorry, I should have given more info!

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7 hours ago, Phongeer said:

Ah, according to the shop, all three items were the culprit. 

They said they couldn't get the fan to work at all. 

And for sure they saw the thermostat was stuck. 

Sorry, I should have given more info!

Hey, I thought you already had put in a new switch...  

In any case it would be good to get all the old pieces back to see how they test out. 

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  • 1 month later...
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This is a timely thread.  Not to hijack but I'm having a very similar issue where the fan isn't coming on and my bike is overheating.  I plan to follow the guidance provided to Phong to hopefully sort out the issue on my 5th gen.

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The first and easiest test is to check the fan blade can rotate freely (cold engine, power off); the side mounted radiators seem to encourage debris to lodge between the fan and shroud and that stops it rotating; I presume you have already checked the fuse?

 

Next up pull the wire off the thermoswitch and ground it to the frame or motor. With ignition on, this bypasses the switch so the fan should be constantly on. If you have no joy here, the pull out your multimeter and find the 2P plug that powers the fan from the harness, and check for 12v.

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