Barr's Leaks -- Overheating! (please help!) - Kawasaki KLR 650 Forum
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post #1 of 28 Old 08-15-2019, 06:37 AM Thread Starter
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Barr's Leaks -- Overheating! (please help!)

Hi - I've got a cooling system problem, and I need help from the community.

Summary: I added 3-4 ozs. of Barr's Leaks to fix a small radiator leak, the bike overheated after just a few miles - and I'm flummoxed (and bummed)!

More detail: I developed a small leak in my radiator (10 ml - 1000 miles) on the inside of one of the vertical "vanes" and decided to gave the local radiator shop a try - they gave it back to me a few days later telling me that it cannot be repaired as "the core is no good" due to the aforementioned leak.

I reattached the radiator and tried 3-4 ozs. of "Barr's Leaks", following the directions (fill radiator, idle for short duration, check for leaks). The bike got good and hot (about 2.30 on the thermometer), but the fan didn't go on and nothing leaked. After cooling down, I rechecked the coolant level (OK), buttoned up the Gen 2 plastics and went for a test ride.

It got HOT under load and hit the "2.00" mark on the thermometer after one of Denver's long signal lights and about a mile and knew smothing was seriously WRONG. I went a few blocks, let it cool down to mid-range and eventually made it home again. I can't say whether the fan came on, but I don't think so. I've since pulled the radiator and flushed it out as best as I can, but now I wish I'd not done anything and just lived with the small leak.

Hypothesis: One of the cooling system components (radiator, thermostat, water pump) got clogged by the Barr's Leaks, inhibiting coolant flow and causing overheating. (?)

- What do you think? Is it possible that flushing the radiator will do the trick, or could the water pump and/or thermostat be so plugged up by the "Barr's Leaks" that further disassembly is required?

Thanks, and any advice will be greatly appreciated - I feel kind of emasculated with the bike out of service. [sad, emasculated face]

~Tom
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post #2 of 28 Old 08-15-2019, 09:11 AM
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I used Barr’s Leaks in a car once. Like you, I regretted it.

I would drain, flush and refill the entire cooling system with Honda Type 2 anti-freeze or equivalent and then see what happens.

Next, I would suggest looking for a replacement rad on eBay.

To me, what you describe, isn’t overheating if the fan is not coming on.

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post #3 of 28 Old 08-15-2019, 09:36 AM
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A couple thoughts;

- either the fan did come on, somethings wrong with it or you weren't actually overheating. I'd start by checking your fan.

- bars leak et al are all poor bandaids for a proper rad repair and are known to clog the rad.....especially small rads; I'd avoid it at all costs. Not sure how easy it will be to flush out all that crap as you don't want to buy a new rad and have it plug up too.


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post #4 of 28 Old 08-15-2019, 09:51 AM Thread Starter
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Thanks for the responses - let me give a short UPDATE...

Since both hoses are disconnected, I poured water into the top hose and blew into it, which forced coolant out of the bottom hose. I've since flushed about 1/2 gallon through the system this way, to the point where it flushes "clean" water out of the bottom hose

This makes me think that the thermostat and waterpump might not be too clogged, and the radiator (since flushed) was the major bottleneck.

- I plan on checking the fan switch, etc with the multimeter after work, and I'll check the fan fuse, also. I also see a new radiator in the future, too...

Any thoughts?
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post #5 of 28 Old 08-15-2019, 09:54 AM
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The KLR cooling system normally operates at a too cool temp, needle barely 1/8th scale at 160F.

The cylinder head temp sender will need to get to about 5/8ths scale or 220-230F before the fan sender at the Cool Bottom of the radiator gets Up To 203-214F to switch ON the fan.

So I'll call your system 'perfectly normal' for a stock system. Your engine is Not Too Hot unless the temp needle is touching/entering the Red Zone!

Many of us install the Watt-man Thermo-Bob radiator by-pass system to Raise the normal operating temp UP to 1/2 scale or 195-205F for steadier over-all engine temperatures.
https://shop.watt-man.com/Thermo-Bob...-YEARS-TB2.htm

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post #6 of 28 Old 08-15-2019, 10:19 AM Thread Starter
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Thanks for that explanation - the needle never hit the red zone as, before it did, I pulled over and let it cool down for a few minutes when it became obvious that it wasn't going to cool down by itself.

It takes a little bit of hard breathing to get the water to push through the lower hose, but it's coming through clearly and also clearly for the radiator, so I'm hoping that it isn't ruined.
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post #7 of 28 Old 08-15-2019, 12:56 PM
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Quote:
Originally Posted by KLR Kool-Aid! View Post
Hypothesis: One of the cooling system components (radiator, thermostat, water pump) got clogged by the Barr's Leaks, inhibiting coolant flow and causing overheating. (?)
My diagnosis:

Possible PARANOIA.

As mentioned above, unless you're into the far red zone, you're NOT "overheating."

A quick check of your fan; short the lead to the thermal switch (bottom or radiator) to ground; should activate the fan. Switch ON, Generation 2s; no matter,
Generation 1s.

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post #8 of 28 Old 08-15-2019, 01:07 PM Thread Starter
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Thanks -

Paranoia, or mechanical hypochondria, may be a possibility but I have to mention that I've never seen my bike get that hot before so I really think that my actions with the Barr's leak did something (bad) to it. It never usually gets above half-way, even at long idles or when trudging along the trails at 15 mph, so this was an entirely new experience.

I'll be checking the fan (fuse, switch, etc.) after work, and I plan on putting the freshly flushed radiator back on shortly after that if I don't see anything amiss.

I really hope that flushing out the system and cleaning out that viscous "goo" does the trick, and I really appreciate all the advice and guidance.
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post #9 of 28 Old 08-15-2019, 01:56 PM
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Quote:
Originally Posted by KLR Kool-Aid! View Post
I really hope that flushing out the system and cleaning out that viscous "goo" does the trick, and I really appreciate all the advice and guidance.
Unless fluid flow dynamics changed radically, no cooling system coolant passage or orifice exists small enough to be vulnerable to the "goo" of Barr'a Leaks, AFAIK.

You can peek into the radiator, witnessing whether the coolant circulates after the thermostat opens. From your comments, I understand your temperature gauge has never registered in the far red zone.

I'm surprised you resorted to Barr's Leaks . . . question: Did the Barr's Leaks seal the leak? Let us know if the radiator leaks after the flushing; understand you've not tried epoxy sealant nor is radiator shop soldering appropriate.

Service manuals contain procedures for testing the fan thermal switch (lower radiator). If the fan rotates when the thermal switch lead is shorted to ground (ignition ON with Generation 2s), you might test the switch to insure it's doing its part (if your fan doesn't turn on when the engine temperature rises).

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post #10 of 28 Old 08-15-2019, 02:53 PM
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There is a small hole in the thermostat that allows air to vent and a small amount of coolant to circulate when the thermostat is closed.
This small amount of flow causes the engine to run too cool. The bleed hole in the thermostat could have been blocked by the Barrs Leak.
That would stop any flow through the cooling system until the thermostat got hot enough to open which is probably somewhere around 180 to 190 degrees.
If you flushed the cooling system and water can be pushed through the bleed hole should be clear.
I would make sure that the rad is not blocked and then put it together again and see what happens.
Also check Amazon.ca for a replacement rad.

Terry
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