What? Another fan thread? - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 33 (permalink) Old 02-07-2016, 05:56 AM Thread Starter
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Question What? Another fan thread?

Hey all!

I have finally after several months working with the previous owner acquired my machine. Rode her 35+ some-odd miles home over the mountains from his shop. Much work had to be done before that ride was possible, much rebuilt in the shop, but that's another story.

On the way back the coolant reservoir overflowed after much riding and finally meeting city traffic. With only about 8 miles of inner-city rush hour traffic to go i endeavored on until finally she died and battery wouldn't kick her over. Pulled over and we both cooled off for about 20 minutes, started her back up, head home, and took a look at her this morning. Battery problem was obvious, the shop has a "genius" mechanic. One of the cells was bone dry, another was about half way up the wall, the others were fine. Replaced the battery with an ETX15L AGM. With that problem solved, i refilled the coolant, restarted, let her get warm, shut her down and she sucked up a full reservoir of coolant. Refilled, that's all fine now too.

Talking to my friend, the shop owner on the phone, he was asking about the fan. And sure enough, as far as i know the fan hasn't yet turned. So, i have read all of the various troubleshooting articles about fans in this section of the forums, and it will be tomorrow before there is enough light to ground the fan-switch, etc. I combed through the maintenance manual, etc. as well and i still have one question i simply cannot find the answer...

What is the temperature ( on gauge or otherwise ) where the fan should turn itself on? Should it just turn on after the bike is more or less idled warm? Does it turn on only when it's sensing extreme heat? I am tempted to just go ahead and put in a ground toggle to bypass the switch as several have suggested ( as well as the shop owner ) but since this is my first VN750, i still haven't a clue when i would turn the switch on myself. If it runs constantly on a switch while the engine is turning, is that going to pull down the electrical system... lose battery life? Is the fan loud enough to hear while out in typical traffic? On the flip side of the coin is a very wise anecdote: if it ain't broke fix something else, like my ears.

Other than that, she simply howls... she has a lot of minor problems, but most of them are cosmetic or broken items and she needs TLC. So this fan question is basically the only thing standing between riding on "reliable" and "worry". Know what i mean?
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post #2 of 33 (permalink) Old 02-07-2016, 08:23 AM
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on my bike, the fan turns on at just about 1/2 way on gauge.. maybe a little higher.. it does not run full time (when ign is on). I cant really hear my fan when sitting still and it turns on, but I can sometimes feel an increase in warm air around the legs (I live in the south, and usually have shorts on..)

the ground to bypass the temp switch in the bottom left of the radiator is a testing method in my opinion.. I think you would be taxing the charging system if you left it running all the time. if you ground the wire and the fan runs, then everything else in the circuit is working properly and you just need the temp switch.

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post #3 of 33 (permalink) Old 02-07-2016, 10:20 AM
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Same here, I don't always hear the fan, but can feel the hot air when it kicks on about midpoint of the gauge. Sometimes at a stop I'll just lean over and look at the blades.

When my fan quit, the spade terminals in the Junction Box plug were loose. Just had to pull them out of the plug, then pinch them with pliers to fit tight. I grounded the fan switch wire then wiggled the wires at the JB plug to find the loose spade. It's one of the blue wires, I think.

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post #4 of 33 (permalink) Old 02-07-2016, 03:12 PM Thread Starter
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Cool thanks and update

Thank you both for the info. Pulled the wire/socket off the fan switch, used some #2 high grade toilet tissue to sop up the oil glut around the switch's tab and inside the socket using a J.C. Penny stock number #NSN 7510-00-958-0743 paper clip which fortunately for me, somebody had left nearby in the weeds of the parking lot. They must have been psychic, i guess.

With the wire disconnected from the switch, i shoved a flat end screw driver into the socket and used the neck of the same to ground the JB relay's coil circuit to a nut on the frame. The fan started to whir which made me smile.

So now i am thinking about a mod. I know eventually someday that switch might just fail ( presuming it's working now ) and leave the fan running all night. And i like the idea of a switch on the handle bars to avoid that situation. I also like the idea that the engineers designed it to be automatic so i am thinking about a mod that does the best of both worlds. An LED could be run in series with the coil side of the JB relay to light up whenever the fan is supposed to be on. A switch could be run in series as well and simply turned on when running, off when parked, and instead of being an override, being an enable/disable switch for the control side of that system.

I took her for a short ride today but the temperature stayed below the halfway mark so really don't know yet if the temperature switch is actually working. There is really no reason to doubt that switch though since it was out of circuit due to all the oil in that connector on the way home the other day. There is equally no reason to believe that i have a good connection there either yet. So for now, i am happy at least a "culprit" was found and can monitor the situation with an informed perspective.

Thanks again and if you have any ideas about that mod, let me know. I'm going to hunt around for LED toggles that can get that mod job done.

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post #5 of 33 (permalink) Old 02-07-2016, 03:57 PM
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If you let it idle long enough, the fan should kick on.

If the fan switch happens to be at fault, an LED on the bars would never light. The switch is what activates the JB relay.

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post #6 of 33 (permalink) Old 02-07-2016, 03:58 PM
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one thing to remember, if needed, the fan will run for a short time (usually less than 1 - 2 minutes, often only a few seconds) on shutdown if the coolant is hot enough.. Mine does this fairly often during the summer after riding.

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post #7 of 33 (permalink) Old 02-07-2016, 05:05 PM Thread Starter
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Quote:
Originally Posted by Spockster View Post
If you let it idle long enough, the fan should kick on.

If the fan switch happens to be at fault, an LED on the bars would never light. The switch is what activates the JB relay.
Exactly. So the idea is that while riding, a quick check of temp-gauge and the LED should tell the story. If the gauge is leaning to the right and the LED is on, everything is fine ( at least on the sense/control side ). It won't ever really mean the fan is actually turning, just take the fun out of troubleshooting with a screwdriver while on the highway.
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post #8 of 33 (permalink) Old 02-07-2016, 05:34 PM Thread Starter
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Quote:
Originally Posted by michiganteddybear View Post
one thing to remember, if needed, the fan will run for a short time (usually less than 1 - 2 minutes, often only a few seconds) on shutdown if the coolant is hot enough.. Mine does this fairly often during the summer after riding.
I get the drift of that as well as what Spock was saying.. i suppose if it's really worth doing a "full" mod, what would do the trick is two switches and an LED, and instead of the LED watching the control side, since it's on a relay anyhow, it should be watching the fan/load side. What's the difference if the relay has juice but it's stuck or there's a bad connect to the fan some place? The LED should only light up if the fan is actually turning. One toggle would allow interruption of the control side of the relay, and the other toggle would parallel the fan-switch to override it. Simple circuit. Two switches, one in series, the other in parallel to either defeat or enforce that relay either way.

The LED on the load side has quite a few options, but without getting too difficult, something between an 8k to 15k resistor in series with it to ground would monitor if juice is "supposed" to be turning the fan, rather than if the fan is actually turning. They used to call things like that "idiot" lamps where i come from.

To monitor if the fan is "actually" turning with an LED would properly require a transistor in series with it on the ground side. That's where it gets to be a bit more than its worth bothering since as mentioned, just looking at the fan tells the story there. The idiot lamp is only there to warn one to pull over and see for themselves. if the lamp is on and the gauge is leaning to the right, then the bike is doing the best it can to cool down.
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post #9 of 33 (permalink) Old 02-07-2016, 06:26 PM
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If you were riding in cool weather, the fan may never kick on, and it could take quite a while just to reach normal temp, if it ever does. 35mph in the summer is enough to cool mine without the fan.

Don't know if you do ebay, but there are fan switches on there reasonably priced, just have to watch for the deals. $30 is pretty high in my opinion.

A fully functioning charging system drops about 1 to 1.5v when the fan is running. So running the fan more than needed could run into trouble on a long ride.

You can test the fan sw. with an ohm meter and a pan of boiling water.

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Shaved w/UniPK92+Stock Jets-TPE/MOSFET-Shinko Tires-AGM batt-bags-chrome-LEDs...more
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post #10 of 33 (permalink) Old 02-08-2016, 12:57 AM Thread Starter
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Quote:
Originally Posted by Spockster View Post
If you were riding in cool weather, the fan may never kick on, and it could take quite a while just to reach normal temp, if it ever does. 35mph in the summer is enough to cool mine without the fan.

Don't know if you do ebay, but there are fan switches on there reasonably priced, just have to watch for the deals. $30 is pretty high in my opinion.

A fully functioning charging system drops about 1 to 1.5v when the fan is running. So running the fan more than needed could run into trouble on a long ride.

You can test the fan sw. with an ohm meter and a pan of boiling water.

I'm so way not a tuff guy, but my garage has a palm tree that blocks the sun sometimes and has a asphalt floor if you get my drift. I think if i had a meter, the best test for that switch would simply be to idle the bike instead of pulling it out and having to refill the radiator.

Since it's only a continuity test, i might just do that tomorrow just to make a meter. Too bad Radio Shack went out of business though. But on the bright side, there are enough worn out appliances tossed on the street in this part of town that i can easily find an LED. Somebody tossed out a nice Magnavox flat screen recently that i am going to rip apart for parts. Simple continuity tester is just two leads one on that tab, one on ground, a 1k resistor, an LED and a AA battery ( or AAA or whatever works ). The switch should eventually close somewhere around the time the temp gauge starts leaning to the right.

I am SURE, however, that the oil that built up in that connector was the problem since i know where the oil came from and when. I also know that the mechanic at the shop may have ridden the bike around the block or something but certainly never got it hot enough to need the fan.... then on the other hand, since he was charging batteries that had 1.5 cells completely dry, what's the difference how hot it got when he was checking out the bike? ( shruggs )

What *happened* about a month ago, the first day i finally had her paid for and pink slip in the mail, etc... was on the way home, she only lasted about 3 miles down the road and then had what i will call a blowout. I had just begun to shift into third, clutch was in, and suddenly WWWwwwRRRRRRRRIIIIIIIIIII..... she was at max RPM which sort of freaked me out for a sec, i had to hit the kill switch, to which she replied with one seriously enormous backfire, oil splattered all over the place from several sources, and gratuitous amounts of white smoke as various fluids boiled off her fins, etc. etc.. My only choice, that far away, was to have her taken back to that shop. The OWNER of the shop, is a very cool guy and hauled it back for no charge, and thus began a month of them finally finding out that the previous owner of the bike had rebuilt the carb using his own home-made parts. They replaced the head gaskets which blew, seals, several hoses, all sorts of various things, and this is the part of the story i sort of glossed on over at the top of this thread. So... basically, i am about 99% sure that connection was simply fouled and seriously, this morning after pulling it off, it was sopping wet with oil inside and on the tab.
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