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Discussion Starter #1
The cooling fan switch on my 2008 went out on me the other day, so after checking with the local dealers, they (of course) didn't have the part and I got the old, "Its $92.93 and I can get that for you in 5-7 days, buddy."
I can't wrap my mind around paying $92.93 for basically what is an electric thermostat, both my tires cost a little over $100.00ish. So I'm thinking about wiring a switch and just flip it on when the temp gauge gets to moving up, has anyone ever done this?
I'm pretty sure I won't forget to turn the fan on 'cause I constantly check the temp gauge.
If I have to get another switch, I'll order it online, for a couple dollars cheeper, wait the same amout of time. \
Thanks
 

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a 15-amp single-pole single-throw (SPST) switch across the terminals of the thermal fan switch in the radiator should do the job.

Look at RoberTx's '08 wiring diagram in the link below; you'll see how the thermal fan switch passes the entire cooling fan electrical current when its thermally-sensitive contacts are closed:

http://www.google.com/imgres?imgurl...fvTem2Lsn2gAe8z4GUDw&ved=0CCYQ9QEwAw&dur=6822

CAVEAT: '08 and later only.

Pre-'08? A 10-amp SPST switch between the thermal radiator switch lead and ground works fine.

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Now, a question: How do you KNOW your thermal fan switch is defective? Is your fan fuse operational? Fan motor o.k.?

To isolate the problem, JUMP the electrical contacts of your thermal fan switch; fan should operate, whether thermal fan switch is serviceable or not.

Fan still doesn't rotate? Could be blown fan fuse, interrupted wiring circuit, or . . . defective fan motor.

I'd check the fan fuse (ohm-meter) and fan motor (jump + 12 VDC to the hot side) before I replaced the thermal fan switch; that component can be tested by cooking it in a pot of water with a thermometer; contacts should close (ohm-meter) at about 200 degrees F., IIRC.

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[EDITED] Now, a philosopical discussion; your TEMPERATURE GAUGE measures the [coolant temperature at the] cylinder head; NOT the temperature of the coolant [at the thermal fan switch in the bottom of the radiator].

It is possible to have a high cylinder head [coolant] temperature (registered on the temperature gauge) with coolant insufficiently hot enough to activate the thermal fan switch [at the bottom of the radiator].

An AIR POCKET in the radiator and coolant plumbing can cause this condition.

AIR POCKETS can be eliminated by operating the engine 'til the thermostat opens and the coolant circulates in the radiator, radiator cap OFF, while the cooling system is BURPED. After burping, top off coolant in reservoir and radiator, replace radiator cap.
 

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Discussion Starter #3
The fan works when I put a jumper across the terminals, checked the switch by putting an Ohm meter on the terminals and suspending in coolant and turning up the stove.
Got an open reading.
Actually I'm going to use a 10amp aircraft circuit breaker,( I have a bunch of them) for the switch on my dash.
 

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The fan works when I put a jumper across the terminals, checked the switch by putting an Ohm meter on the terminals and suspending in coolant and turning up the stove.
Got an open reading.
Actually I'm going to use a 10amp aircraft circuit breaker,( I have a bunch of them) for the switch on my dash.
10 amp may be somewhat light for the application; the Kawasaki factory fuses the fan circuit with a 15-amp fuse.
 

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Now, a philosopical discussion; your TEMPERATURE GAUGE measures the cylinder head temperature; NOT the temperature of the coolant.

It is possible to have a high cylinder head temperature (registered on the temperature gauge) with coolant insufficiently hot enough to activate the thermal fan switch.
That is helpful but not quite accurate. BOTH sensors measure coolant temperature: it's just that the temperature gauge measures it up in the cylinder head, and the fan switch measures it on the 'cold' side of the radiator.

So yes, you can have conditions where the temp gauge is above 220F and the fan doesn't come on - these would be low coolant flow conditions such as a stuck thermostat or coolant impeller that is loose on the shaft. In those conditions, you would see a large amount of temperature drop across the radiator (since the coolant is moving so slowly and has a much-larger-than-designed dwell time) and the coolant at the bottom of the radiator is cool enough that it doesn't trigger the fan.

Agreed that an incorrectly-burped cooling system can cause all kinds of problems. These bikes only hold 34 to 38 fluid ounces of coolant, and it doesn't take much (ie, 6 missing ounces) to throw them off.
 
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That is helpful but not quite accurate. BOTH sensors measure coolant temperature: it's just that the temperature gauge measures it up in the cylinder head, and the fan switch measures it on the 'cold' side of the radiator.
I stand corrected; Part # 92066-1183, "PLUG,SENSOR WATER," the "temperature sender"in the cylinder head, obviously measures coolant temperature at that point, which may vary from the coolant temperature at the thermal fan switch in the bottom of the radiator.

Corrected copy follows:
[EDITED] Now, a philosopical discussion; your TEMPERATURE GAUGE measures the [coolant temperature at the] cylinder head; NOT the temperature of the coolant [at the thermal fan switch in the bottom of the radiator].

It is possible to have a high cylinder head [coolant] temperature (registered on the temperature gauge) with coolant insufficiently hot enough to activate the thermal fan switch [at the bottom of the radiator].
 

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I am a pinhead and would never remember to hit a switch before its too late.
Question: Is there a switch that activates at a lower than 200 temp? Seams that 200 at the radiator is a little too hot at the head from my old dude recollections.
 

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In my opinion; "No," and, "Not at all."

First, doubt you could find a conforming thermal switch activated at lower temperature.

Second, the threshold temperature, 201 degrees F., of the thermal switch is designed to augment cooling when necessary, keeping the engine operating within safe limits.

A common modification, Thermo-Bob installation, RAISES the nominal engine coolant operating temperature, without reported maintenance issues.

Manual fan activation switch? Totally redundant and superfluous to the thermal switch,IMHO. "Don't knock it unless you've tried it?" Been there; done that!
 

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Try this one for $37. You might have to reuse the old O-ring.

List: Search for 'tfs596' | O'Reilly Auto Parts
Three questions, GoMotor!

1. Does the part fit the KLR radiator connection?

2. What is its temperature setting (as mentioned, OEM is 201 degrees F.).

3. Not so critical on Generation 1s, with a low-current voltage controlling a relay, but perhaps of interest with a Generation 2 installation (which must handle full fan current (15 amp fuse, IIRC): Will this switch handle the current?

I'd go back a little, basically, and ask: What overheating problems (e.g., coolant boiling; temperature gauge needle in far right red region) have been experienced with the stock cooling system?

Even with a low-temperature thermal switch, at the end of the day, in the long run, the engine is dependent upon coolant circulation and air flow (including the contribution of the cooling fan) for cooling; neither of these is changed by the trick switch.
 

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That part number is for a Borg-Warner fan switch used in a Geo. I noted it down from something I read several years ago. The guy who used it said it fit, but he had to use his old O-ring. O'Reilly does not give the cut in/out temps.

After a little more searching on a Goldwing site I found the specs which I edited into my post above. It seems too cold for the KLR.

That switch has to be a standard automotive mass produced low cost item.
 

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After a little more searching on a Goldwing site I found the specs which I edited into my post above. It seems too cold for the KLR.
Well, at somewhere around the 190 degree F. range, may be just what's desired by Squidly (as in, lower threshold than stock).

Yet . . . the Thermo-Bob aficionados might not like to activate the fan so soon! :)

Again, I think a lower-threshold thermal switch is an elegant solution to a non-existent problem (given safe functioning of the OEM cooling system), but . . . to each his/her own.

I mentioned I considered the manual fan switch redundant/superfluous; still do, but . . . I installed a jewel indicator light, illuminating whenever the fan is activated . . . a useful piece of instrumentation, IMHO. Provides instant end-to-end check of fan circuitry, also--verifies fan functioning when coolant temperature reaches threshold level.

So . . . properly filled with coolant, radiator correctly burped . . . at idle in the summertime, temperature goes up, fan kicks in, temperature goes down . . . what? ME worry? :)
 

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LMBO!!! It's very clear how your lack of concern is dripping into the next post Damocles.


You all are great. Forgive me and my ignorance. I did a little investigating as well after I typed the post.
Now realizing that thumpers are only slightly different than the V8's I was used to when I had the time and played knuckle dragger. A hot head equated to a cracked one.

Cast iron is just like aluminum only different after all.

Appreciate the attention!!!!
 

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Regardless of the presence or absence of my concern, Squidly, it's your bike; modify it to suit yourself, the only significant judge of the merit of your efforts.

Not to hide my own perception/opinion, I think a stock cooling system, in production unchanged for over 25 years, without any known maintenance issues or component failures traceable to the stock cooling system operated within safe conditions, approaches, "good enough."

You're more than free to install a lower-temperature thermal switch, even a manual fan activation switch if you see fit; as in:





Although you have not described the MAGNITUDE of your overheating problem (e.g., coolant boiling, temperature gauge needle in far right red zone), I'll point out: No matter whether trick (lower temperature) thermal fan switch, manual fan switch, even Thermo-Bob, the engine ultimately remains at the mercy of coolant flow and air circulation (including cooling fan air); unaffected by any of these modifications.

Still, your bike; let us know how any modifications work out for you; best wishes!
 

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Damocles,
Forgive me. I didn't. I'm at work and only swing in in short spurts.
I don't have a heating problem. Well I don't think so anyway. I had the pig for 86 miles so far. Has 8,200 on it. Been out of it since the early 70"s. I also wasn't to concerned. I have spent way more time on the forum than the bike. With this I've haven't read where temp is a problem for any year. I was just curious. Techno has come along way since my day, so to speak.

It's a learning thing!!

I actually decided on the KLR because of the passion I was seeing in the forum.

Inspirational at the least!!
 

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I am a pinhead and would never remember to hit a switch before its too late.
Question: Is there a switch that activates at a lower than 200 temp? Seams that 200 at the radiator is a little too hot at the head from my old dude recollections.
Mid range on the temp gauge is 210 deg F. That is the temperature of the water off the head. Under normal operation the water at the bottom is cooled about 10 degrees below the entering temperature at the top. So the temperature at the fan switch would be around 200 degrees when the gauge is at mid range and the bike is moving.
 

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Mid range on the temp gauge is 210 deg F. That is the temperature of the water off the head. Under normal operation the water at the bottom is cooled about 10 degrees below the entering temperature at the top. So the temperature at the fan switch would be around 200 degrees when the gauge is at mid range and the bike is moving.
No arbument, Squidly, but . . . do you mind sharing your source of information?

From Watt Man's calibrated temperature gauge, seems like 210 degrees for midpoint is about right, IIRC; however . . . wonder about the 10-degree drop from cylinder head to radiator bottom, because . . . on my KLRs, gauge needle must be considerably over mid-range for the thermal switch to trigger the cooling fan.

Clymer claims the thermal switch threshold is about 201 degrees F.

Again, no argument; just seeking a source for the data.
 
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