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Hello,

I know someone will inevitably post a thread that already contains useful info, but I've done some serious searching as it is, yet the internet is a large place and I have specific questions.

Onward. I have a 2007 KLR that runs hot, it is a newly acquired bike and sat for some time before I bought it. In getting it road ready I bled the cooling system from the drain bolt below the water pump and replaced the coolant. I then had to go to work and did not burp the system.

Here we are now and I did burp the system by removing the rad cap and running the bike up to where the temp gauge reads 3/4, which as of right now seems to be its normal idling temp. While I was running the bike I was watching the rad let out some bubbles, especially when the throttle was open, not a lot of bubbles. After about 30 seconds of this, the coolant would spill up and over the radiator from where it was sitting at just full. I would turn the bike off and watch the coolant bob up and down and finally settle. I would then repeat the process and see some bubbles, throttle, coolant overflow, turn bike off, bobbing coolant.

The bike sits at 3/4 temp and it gets there really fast, has first gen thermo bob FYI. MY question: Is the overflow of the coolant concerning and are small occasional bubbles when throttling indicative of a) a lot of air bubbles because I wasn't thorough with my coolant change procedure or b) indicative of a failing gasket, head, water pump seals, etc? There are no other signs of milky oil, white smoke or drinking coolant.

Wes. Thanks.
 

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The bike sits at 3/4 temp and it gets there really fast, has first gen thermo bob FYI. MY question: Is the overflow of the coolant concerning and are small occasional bubbles when throttling indicative of a) a lot of air bubbles because I wasn't thorough with my coolant change procedure or b) indicative of a failing gasket, head, water pump seals, etc? There are no other signs of milky oil, white smoke or drinking coolant.
"NO," to all the above, IMHO!

I now defer to the profound and sage wisdom of forum members, for correction and clarification!

:)
 

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3/4 of temp gauge scale in the garage suggests to me that the cooling fan is NOT Operating properly.

Can you spin the cooling fan with your finger? Is the cage bent?

Disconnect the wire from the switch at the bottom of the radiator, touch it to a paint Bare cylinder head fin, if the fan doesn't run check the FUSE behind the RH coolant reservoir tank. If the fan MOTOR does run, do the blades turn or can you hold them (melted center drive)?
 

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3/4 of temp gauge scale in the garage suggests to me that the cooling fan is NOT Operating properly.

Can you spin the cooling fan with your finger? Is the cage bent?

Disconnect the wire from the switch at the bottom of the radiator, touch it to a paint Bare cylinder head fin, if the fan doesn't run check the FUSE behind the RH coolant reservoir tank. If the fan MOTOR does run, do the blades turn or can you hold them (melted center drive)?
Sound procedure for checking cooling fan circuit, end-to-end, but . . . ignores the radiator thermal switch.

No Thermo-Bob on my Generation 1, but . . . IIRC, cooling fan does not energize before temperature gauge needle excursion exceeds 3/4 scale. Yet, . . . cooling fan DOES activate at higher values; temperature gauge needle then goes down.

While my cooling fan may not be operating properly, we've survived years of idling in hot summer traffic, so far.
 

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If the fan switch does not turn the fan ON by about 3/4 temp scale it must be faulty, simple as that.

It is kinda' hard to make water 220-240 F degrees with-out a pressure cooker on the kitchen range, but How would you connect the tester wires?
 

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It is kinda' hard to make water 220-240 F degrees with-out a pressure cooker on the kitchen range, but How would you connect the tester wires?
That's exactly what sprung to mind -
-connect two very fine teflon insulated wires onto the fan switch,
-set this afloat on a small wooden block that keeps the tail end submerged
-don't let the brass tail touch the bottom of the pan
-place the apparatus inside the pressure cooker
-set the weighted bobbin for 250F

Ideally you'd have a second set of leads for a thermocouple to monitor actual temps.
 

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Discussion Starter #8
Thanks for the responses.

The fan does work and comes on right above halfway along the temp gauge. To be honest, I always thought the fan was just there to "maybe" help out the radiator, I just cant imagine it having a serous effect on it once the temp gets high enough to burn my leg.

I am mainly concerned that my coolant system is messed up in some way because the bike runs hot almost immediately after ignition and after long rides with good cool air, will still hover at 3/4 or above, which could be a symptom of a bad head gasket or water pump or twenty other things, it could also be because the thermo bob is doing its job too well. My 99 KLR (w/ third gen thermo bob) takes at least a couple minutes to go above halfway, but alas the coolant system may be the only thing really working on that bike after 33,000 miles.

I've switched radiator caps between the two bikes because I know the 99 has a working one and so far with the 07s cap the 99 runs at half temp. I was really curious about why the radiator is heating up and over the radiator on the 07 while the cap is off and why I'm still getting small air bubbles after ten minutes of burping - did I overfill the rad by putting 50/50 coolant all the way to the top after flushing? Or is it overflowing because the cap is off and not holding pressure inside when it's hot?

OR is my new KLR a lemon, and should I throw a match in the gas tank? My next step is just to go take it for an extended ride and watch the temp. Final question: If the bike hits the red line for some reason, is there any reason to NOT throw some cool water on the engine, will this create shock?
 

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Alas, there is no test procedure for the fan switch.
Au contraire, Foo!

q.v., "Fan Switch Testing" below:







As to PDWestman's question, "It is kinda' hard to make water 220-240 F degrees with-out a pressure cooker on the kitchen range, but How would you connect the tester wires"

I think the Clymer procedure answers the question to some extent, and . . . from Table 2, below, (q.v., "Radiator Fan Switch Resistance") one can see no water temperature beyond boiling (212 degrees F. at sea level standard atmospheric pressure) is involved (more precisely, 201 degrees F), no, "220-240 F degrees" or pressure cooker need apply! (Just an aside; the coolant temperature measured by the temperature gauge at the cylinder head typically is higher than coolant temperature at the thermal switch at the bottom of the radiator.)



CAVEAT: Copyrighted materials for educational and literary review purposes only.
 

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If the fan switch does not turn the fan ON by about 3/4 temp scale it must be faulty, simple as that.
Rather an absolute statement, seems to me!
It is kinda' hard to make water 220-240 F degrees with-out a pressure cooker on the kitchen range, but How would you connect the tester wires?
The thermal switch closes at only 201 degrees F. (see Table 2 in above post), attainable with an open container of water where meter leads are accessible to the switch; thus, higher temperatures (220-240 degrees F.) and pressure cookers aren't necessary for thermal switch testing.
 

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Yeah, the fan switch is supposed to turn on at between 201 & 212F in the 'chilled' coolant at the 'bottom' of the radiator. But the cylinder head temp controlling the on-dash temp gauge may very well be 220-240F to attain that radiator temp. And if the fan switch does not actually operate by an actual 220 - 240F IT IS Well Beyond specs, is it not?
So, absolutely bad by any published standards.
 

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Yeah, the fan switch is supposed to turn on at between 201 & 212F in the 'chilled' coolant at the 'bottom' of the radiator. But the cylinder head temp controlling the on-dash temp gauge may very well be 220-240F to attain that radiator temp. And if the fan switch does not actually operate by an actual 220 - 240F IT IS Well Beyond specs, is it not?
So, absolutely bad by any published standards.
If the thermal switch cycles at its designed temperature, I would not consider the switch, "well beyond specs." Rather, I'd consider the switch within specification. Looks to me like the radiator fan switch itself alone is, "ignorant." It merely turns on or off depending upon the temperature of its environment. Thus, testing the switch separately, I can't see the the necessity or utility of subjecting the switch to temperatures beyond its specified operational range. If the switch closes at 201 degrees F., I'd expect it to remain closed at 240 degrees F., activating the cooling fan as designed.

As to the temperature gradient in coolant between the cylinder head and the bottom of the radiator, I'd leave that thermodynamic consideration up to the Kawasaki designers and engineers. I'd hope and imagine the manufacturer calculated thermal switch activation at a coolant temperature of 201 degrees F. or higher at the thermal switch, when the cylinder head coolant temperature might be 220-240 degrees F. Don't see the relevance or merit in testing the radiator fan switch separately at temperatures beyond its activation goal. The service manual test procedure does not extend beyond the boiling point of water (212 degrees F.), given the designated test apparatus and equipment.

Clarifying, I understand you believe the cooling fan switch, designed to activate around 201 degrees F., should be tested separately at temperatures of 220-240 degrees F.?
 

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Clarifying, I understand you believe the cooling fan switch, designed to activate around 201 degrees F., should be tested separately at temperatures of 220-240 degrees F.?
No, that is not what I'm saying.

All service manuals suggest a maximum set point for the fan switch of 212F, yes?

But is 220F really that much, too much higher? Is your or my thermometer really accurate?

Of course I believe that 240F of fan switch set point is Too High, regardless of thermometer accuracy.

Indicated cylinder head temp is always going to be higher than bottom of radiator temp.
 

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No, that is not what I'm saying.

All service manuals suggest a maximum set point for the fan switch of 212F, yes?
No. the boiling point of water, 212 degrees F. is the maximum temperature testable by the configuration of the test equipment in the service manual (i.e., open water vessel). Water turns to steam beyond that point, rendering discrete testing at higher temperatures at atmospheric pressure infeasible. Incremental testing up to boiling point remains possible.
But is 220F really that much, too much higher? Is your or my thermometer really accurate?
As mentioned, water turns to steam at 212 degrees F. In the setup shown in the service manual, 220 degrees F. cannot be achieved without pressurization (needs closed vessel) and creation of super-heated steam. As to thermometer accuracy, testing the radiator fan switch offers a good opportunity to calibrate the thermometer: When the water begins boiling, the thermometer should read 212 degrees F. Higher temperatures change the state of water to steam, at atmospheric pressure.

==========================

DISCLAIMER: I don't KNOW any of this. The content is this post is based, as (T. E.) Lawrence of Arabia once said (The Mint, Part II, Chapter 6), "'Well, Sergeant, specifically of course we can know nothing unqualified - but like the rest of us, I've fenced my life with a scaffolding of more or less speculative hypotheses.'" (Lawrence liked to ride motorcycles (and camels) by the way!)

:)
 

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Mr. 1999KLR, I have a few points to bring to the table:

As it is a "new to you" machine, maybe the 3/4 gauge is normal for that machine?

In automobiles, I have seen the same sensor give different readings on different gauges...
Maybe your gauge is faulty? Maybe your expectations are faulty? LOL

I have the good fortune ( really, I'm not so sure about that?) to live in Newfoundland, Canada, where "the week of summer" is not really a joke. Living on an island in the North Atlantic is like that! But I digress....

With my 2006, sometimes I would be riding for 1/2 hour or more before the gauge would get to 1/2, at which point, the thermostat would open and my temperature gauge would drop... Sometimes, (not during the week of summer - LOL) the temperature gauge would barely move at all.

Stock system = wide swings in the gauge as I rode for hours, regardless of the weather.

When I installed my thermobob, The gauge started to rise almost immediately!!! Freaked me out at first, but then the temperature stayed consistent on the gauge. Warm engine showed about 1/2 on the gauge. This is normal behavior for the thermobob.

Upgraded cooling system via thermobob = quick warm up and stable gauge (no swings)….

Do you have access to a lazer temperature gauge to get readings on various parts of the head and cooling system?

2Combs asked about checking the thermostat, Have You?
You can place the thermostat in a pot of water on the stove, as the water temperature rises, the thermostat should open...

It's only science!

Steal one of your moms / better half's good pots and conduct the science experiment... I recommend doing this when she is not around LOL. If there's a meat thermometer I the kitchen, toss it in the experiment pot to see what temperature the thermostat opens.

Report back when you have results.

(Don't forget to wash and put away the weird science pot!!!) THIS IS THE MOST IMPORTANT PART!!!
 

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2Combs asked about checking the thermostat, Have You?
You can place the thermostat in a pot of water on the stove, as the water temperature rises, the thermostat should open...

It's only science!

Steal one of your moms / better half's good pots and conduct the science experiment... I recommend doing this when she is not around LOL. If there's a meat thermometer I the kitchen, toss it in the experiment pot to see what temperature the thermostat opens.

Report back when you have results.

(Don't forget to wash and put away the weird science pot!!!) THIS IS THE MOST IMPORTANT PART!!!
Add a multimeter and a thermometer to your test equipment, and you can test your thermal radiator switch similarly! (Post # 9 above.)

Truth be told, my own cooling system operational test remains coarse and basic: If the cooling system keeps my temperature gauge needle away from the red, it's working.

:)
 

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I just had a customer in my shop yesterday that was trying to test his Cheap New Chinese fan switch to replace his failed Gen 1 fan switch. Said he could only achieve 203F at 5357 ft with tap water on top of the kitchen range.

So thanks to members on this forum, I told him to use undiluted coolant/antifeeze.

He came back later to report that his Cheap New Chinese Gen 1 fan switch turns on at 240F, on top of his camp stove.
We both agreed that 240F at the bottom of the radiator was probably gonna' be too near 270F at the cylinder head.
 

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Fan problems can also be caused by the fan relay. You can check this by grounding the sensor wire against the bare fin and listening for a click. If you hear a click and the fan doesn't come on, then look at the fan itself and the wiring harness between the two. If there's no click, or the click is intermittent, then it's likely the relay assuming you've checked fuses and your battery terminals first. The same relay is found under that little plastic cover on the left side main frame vertical. That little round can in the rubber is the starter relay and you can replace it with the one under the tank in the right side for testing.

Recently i got my KLR all back together after years of storage and i had both a bad relay and corrosion on the harness plug to the fan. Once i swapped the starter relay over i had a click but no fan. I followed the fan wires looking for cuts, shorts, or abrasions, and when i got to the harness plug, unplugged and cleaned it out thoroughly so it makes good contact. If it clicks and the fan turns on when you ground it, then the only other possible electrical problem would be the sensor itself.
 
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