Cooling fan switch / bypass - Kawasaki KLR 650 Forum
2008+ KLR650 Wrenching & Mod Questions For repair, maintaining or modifying discussions related to the newly updated 2008 and beyond, Generation 2 KLR650 Motorcycle.

 2Likes
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 22 Old 06-08-2011, 01:03 PM Thread Starter
1st Gear
 
Join Date: Oct 2010
Location: Broken Arrow Oklahoma
Posts: 80
Cooling fan switch / bypass

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
Icepick is offline  
Sponsored Links
Advertisement
 
post #2 of 22 Old 06-08-2011, 02:03 PM
5th Gear
 
Join Date: Jan 2011
Posts: 4,386
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=...QEwAw&dur=6822

CAVEAT: '08 and later only.

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

------------------------------------

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.

--------------------------

[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.
Squidly likes this.

Last edited by Damocles; 06-08-2011 at 09:20 PM.
Damocles is online now  
post #3 of 22 Old 06-08-2011, 03:52 PM Thread Starter
1st Gear
 
Join Date: Oct 2010
Location: Broken Arrow Oklahoma
Posts: 80
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.
Icepick is offline  
 
post #4 of 22 Old 06-08-2011, 03:59 PM Thread Starter
1st Gear
 
Join Date: Oct 2010
Location: Broken Arrow Oklahoma
Posts: 80
good info on the air bubbles in the cooling system, Thanks for all...
Icepick is offline  
post #5 of 22 Old 06-08-2011, 04:06 PM
5th Gear
 
Join Date: Jan 2011
Posts: 4,386
Quote:
Originally Posted by Icepick View Post
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.
Damocles is online now  
post #6 of 22 Old 06-08-2011, 04:25 PM Thread Starter
1st Gear
 
Join Date: Oct 2010
Location: Broken Arrow Oklahoma
Posts: 80
I should have a 15 amp CB...
Icepick is offline  
post #7 of 22 Old 06-08-2011, 08:57 PM
1st Gear
 
Watt-man's Avatar
 
Join Date: Jan 2009
Location: Phoenix, AZ
Posts: 36
Quote:
Originally Posted by Damocles View Post

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.
Squidly likes this.

Watt-man

'04 KLR650, 172,000 Miles
still on original piston, rings, entire top end. Just an Eagle doohickey, torsion spring and a Thermo-Bob, of course!

www.watt-man.com
Ride it like you own it!

Last edited by Watt-man; 06-08-2011 at 09:00 PM.
Watt-man is offline  
post #8 of 22 Old 06-08-2011, 09:17 PM
5th Gear
 
Join Date: Jan 2011
Posts: 4,386
Quote:
Originally Posted by Watt-man View Post
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:
Quote:
[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].

Last edited by Damocles; 06-08-2011 at 09:22 PM.
Damocles is online now  
post #9 of 22 Old 06-11-2011, 12:45 AM
2nd Gear
 
peter650's Avatar
 
Join Date: Jun 2011
Posts: 127
I wired mine to a switch so i can turn the fan on before it gets hot on a 1st gear trail
peter650 is offline  
post #10 of 22 Old 10-08-2015, 12:41 PM
2nd Gear
 
Squidly's Avatar
 
Join Date: Sep 2015
Location: Wyoming
Posts: 206
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.
Squidly is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Kawasaki KLR 650 Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
2008 klr650 clutch and kickstand safety switch bypass grtfshrmn 2008+ KLR650 Wrenching & Mod Questions 24 10-20-2016 10:02 PM
Cooling Vests klr4evr Bike and Rider Gear 3 05-27-2011 10:47 PM
Anyone ever bypass the kill switch? Hayduke 1987 to 2007 Wrenching & Mods 2 02-04-2007 08:24 PM
Clutch/Sidestand switch bypass? Woodster 1987 to 2007 Wrenching & Mods 7 01-16-2007 08:05 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome