Kawasaki KLR Forum banner

1 - 20 of 28 Posts

·
Registered
Joined
·
126 Posts
Discussion Starter #1
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
 

·
Administrator
Joined
·
3,563 Posts
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.
 

·
Premium Member
Joined
·
2,942 Posts
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.


Dave
 

·
Registered
Joined
·
126 Posts
Discussion Starter #4
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?
 

·
Premium Member
Joined
·
6,684 Posts
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-2-for-KLR650-ALL-MODEL-YEARS-TB2.htm
 

·
Registered
Joined
·
126 Posts
Discussion Starter #6
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.
 

·
Registered
Joined
·
5,567 Posts
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.
 

·
Registered
Joined
·
126 Posts
Discussion Starter #8
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.
 

·
Registered
Joined
·
5,567 Posts
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).
 

·
Registered
Joined
·
197 Posts
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
 

·
Premium Member
Joined
·
6,684 Posts
terry_g,
Standard OEM thermostat in all KLR's is 160F. Nothing else available in oem diameter, until the Thermo-Bob 2 was available. And it is NOT advised to install the TB 2 195F thermostat into a non by-pass system.
 

·
Registered
Joined
·
5,567 Posts
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
Appreciate the considered comment, terry_g!

Just a small detail; I believe the stock thermostat opening temperature is 160 degrees, not 180--190 degrees . . . corrections welcomed! :)

Would a blocked weep hole (even as a function of Barr's Leaks) cause overheating, if the thermostat opens at 160 degrees? Don't know; just askin'!
 

·
Registered
Joined
·
5,567 Posts
terry_g,
Standard OEM thermostat in all KLR's is 160F. Nothing else available in oem diameter, until the Thermo-Bob 2 was available. And it is NOT advised to install the TB 2 195F thermostat into a non by-pass system.
NormK sold me a higher-temperature thermostat he obtained from China, as a replacement for an OEM KLR650 thermostat.

In the, "bad old days," folks used to substitute higher- and lower-temperature thermostats in their automobiles, depending upon the seasonal ambient temperatures expected. Reckon one might use one of these as their, "winter" thermostat.

Haven't ever installed this goodie myself; anyone want to experiment with it?

Don't know if the part is available commercially; even if so, the excessive tariff on this Chinese product might make it economically untenable! Regardless, anyone interested seriously in experimenting with this gadget might talk me out of it! :)

Stand by; I'll try posting an image of the component.
 

·
Registered
Joined
·
197 Posts
I was just guessing at the temp. When I installed the Thermo-Bob kit in my 2017 I could not see a temperature marked on the factory thermostat anywhere.
The bleed hole in the factory thermostat is way bigger than the bleed hole in the Thermo-Bob thermostat. The bleed hole can let enough coolant pass through to over cool the engine when running under light load.
I strongly recommend the Thermo-Bob kit. Over the long term engine life should be greatly increased.

Terry
 

·
Registered
Joined
·
197 Posts
Most automotive and heavy duty thermostats have the temperature stamped into the bulb.
The Thermo-Bob has 90C stamped in it which is 194f. I found the factory thermostat from my KLR and it has a no
temperature stamped on it.
 

·
Premium Member
Joined
·
6,684 Posts
If one looks at the wax motor bulb of Norms Chinese thermostat, one should read '90C'. I ordered 4 from Normk, to help build his initial order. Norm then turned over his contact information to Watt-man and the rest is now history.

If one installs one of Normk/Watt-man 90C thermostats into a non-bypass OEM system, then one should drill a secondary air vent / bleed hole into the outer perimeter of the 90C thermostat body. We do want some reasonable flow of HOT coolant to flow near the wax motor bulb for proper oem type operation. But Watt-man, Normk and myself would rather see a by-pass system installed with the 90C thermostats.
 

·
Registered
Joined
·
5,567 Posts
Most automotive and heavy duty thermostats have the temperature stamped into the bulb.
The Thermo-Bob has 90C stamped in it which is 194f. I found the factory thermostat from my KLR and it has a no
temperature stamped on it.
The Kawasaki Service Manuals list the thermostat temperature as approximately 160 degrees F. (157-162 degrees F., p. 5-3, KLR600 "Base" service manual), corroborated by pdwestman's post # 11 above.

Regardless, I'd be surprised if a clogged weep hole in a stock thermostat would cause overheating, if the thermostat opens within specifications.

BTW, my NormK thermostat has, "90 [degrees] C." stamped; perhaps suggesting it's the same component in the current KLR650 Thermo-Bob kit.

I strongly recommend the Thermo-Bob kit. Over the long term engine life should be greatly increased.
You're in good company, terry_g! Lots of KLRistas share your opinion (including, perhaps, my '08-riding partner who will turn 100,000 miles this summer). How many additional miles do you estimate a Thermo-Bob adds to a KLR650 engine's service life?
 

·
Registered
Joined
·
126 Posts
Discussion Starter #19
Back with some results...

Interesting discussion here...

Having reinstalled the radiator, etc., here's what I've found in summary; it's not overheating as it did the other night, and my fan switch may be suspect. I wouldn't recommend the snake oil.

Fan: I checked the fuse (OK), and then ran power to the white connector (located next to gas tank) that sends power to the the fan motor - the fan worked. I ran a test lead from one of the small connectors on the bottom of the fan switch with the ignition on and the white (power) connection connected and the fan fuse blew. (Perhaps I accidentally touched something wrong...). I figured that the fan blows so rarely that I'll not worry about that for right now and check that again when I get more 15 Amp. micro-fuses.

Cooling system: Reattached everything, filled it up, ran briefly and checked for leaks - none. I went for the same ride that I'd taken the other day to replicate test conditions - the bike ran a little hotter than usual (I've 45 k with this bike), but you could see the cycling of temperature when you started to get a little wind. The temperature gauge read between 1/2 (3.00) and normal the entire time, so I think that's acceptable. I'm taking it camping this weekend, so that'll be it's stress test.

I've enjoyed learning a lot about the KLR cooling system and I think that a stronger radiator will be my long term fix. Even with crash bars, the radiator seems susceptible to damage and the snake oil was a learning experience that I wont repeat.

Thanks so much for the help. Fair skies and good winds, all!

~Tom
 

·
Registered
Joined
·
5,567 Posts
But . . . did the Bar's Leaks seal the radiator?

Or, is your radiator still leaking?

From your posts, I understand the Bar's Leaks (aka, "snake oil") is the only repair/maintenance action you have performed addressing the leak.
 
1 - 20 of 28 Posts
Top