Bubbles in Radiator Help please - Kawasaki KLR 650 Forum
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post #1 of 7 Old 04-06-2020, 10:14 PM Thread Starter
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Angry Bubbles in Radiator Help please

Aloha All,

So the story is that I just bought a 2009 KLR650 for a really good price. Having ridden it for about a week I noticed in over heating in traffic and having that smell of coolant evaporating.

So let the forensics begin. First on the list was the overflow tank. It was dry. What I found was that the overflow intake spout at the bottom of the tank had been glued on and sealed off, Which means there was nowhere for the overflow to go and to return to the radiator.

So I ordered an new over flow tank, thermostat and a radiator.

The next thing done was to check the thermostat which I removed and reassembled without it so as to check the waterflow from the radiator.

Now without the thermostat I refilled the radiator and sealed the radiator cap. The radiator has a leak in it about halfway up the side of the cooling fins.

Next thing I did was remove the cap on the radiator to see the flow of water inside. The water seemed to be moving well so I have ruled out the water pump for now.

The problem now is a steady flow of air bubbles in the radiator water. I don't see any water in the oil and the water in the radiator isn't really frothing up like I have seen some cars do when the head goes bad.

So I am thinking I have a bad head gasket?

Or is it an Exhaust valve that need adjusting? Or can I just reseat the head bolts without taking them off? Can I use a product in the coolant to seal it or do I have to have the head gasket redone? I know about shaving the head and all that and if it has to be done I will take it to a pro.

My last question is if the little refill tube at the bottom of the overflow tank was sealed would that cause all the problems with a leaking radiator and bad head gasket? There would be no place for the pressure to go would it?

This is my first post on this forum so go easy on me.'

Mahalo All.

Last edited by Ric Sheridan; 04-06-2020 at 10:47 PM.
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post #2 of 7 Old 04-07-2020, 12:17 AM Thread Starter
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Nobody can help?
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post #3 of 7 Old 04-07-2020, 09:03 AM
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I very much doubt its a head gasket failing. Is there any sign of moisture in the oil?
It could be air trapped in the cooling system that needs to clear.Did the electric fan kick in when the engine was hot?
Put it back together with the new thermostat and rad then make sure the fan is working.
Someone should be here to help with testing the fan circuit and sensor.

Terry
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post #4 of 7 Old 04-07-2020, 11:13 AM
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Quote:
Originally Posted by Ric Sheridan View Post
Nobody can help?
Aloha to you also, are you in Hawai'i?
A late start could explain a lack of traffic & suggestions.

As Terry said, don't jump to conclusions. Probably Not a bad head gasket, nor exhaust valves (I don't know where you could have ever gotten that idea.).

The radiator pressure relieve valve in the center of the cap is rated at 14-18 psi according the manual. The outer cap seal probably can't contain much more pressure, I'll suggest maybe 25 psi.
If the heated / pressurized coolant can't be relieved to the reservoir because of a collapsed bottom nipple on the reservoir, then it will relieve pressure somewhere. Usually from the top gasket of the cap, & wet the top radiator tank. Or from a damaged area.

The combustion chamber head gasket has to contain 100's of psi even during idling. So with the overflow hose disconnected from the bottom of the reservoir, cooling system filled & engine started, lets unplug the fan connector from the radiator sensor.
Now use a piece of wire to bridge the contacts, the fan should now run. Does it? Leave that fan disconnected. Leave the engine running. A Gen 2 fan only runs if key is on.

If you could use a window fan to blow cooling air from the RH side of forks across the exhaust header & coolant reservoir that would be good.

We are looking to get the temp gauge up to about 1/2 scale and NOT have any pressure relief from the overflow hose, yet. If your system was to be relieving pressure below 1/4 - 3/8 temp gauge I'd guestion the head gasket.
When temp gauge reaches 3/4-7/8 scale, reconnect the cooling fan. Does the fan come on? Does it start to reduce the temp after about 30-60 seconds. Note at what temp the fan turns off (1/2-5/8?) & at what temp it comes back on (5/8-3/4?).

The engine & cooling system is NOT overheating unless it is consistently 7/8 - fully in Red Zone.

At least this is what I would do.

Gen 2 normal temps without a Thermo-Bob.
1/4-3/8 scale roliing down the road. 1/2-3/4 scale idling at a long stop light.
Normal.

With a Thermo-Bob, 7/16 - 5/8 scale most of time. Perfect.
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pdwestman
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post #5 of 7 Old 04-07-2020, 08:55 PM Thread Starter
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I live at Sunset Beach Oahu,

So I tested the fan all morning and the only way I can activate it is if I jump it directly to the battery. The paper clip test did nothing. I can't get any voltage anywhere. Even at the fuse. The test on the temperature switch at the bottom of the radiator on the stove top didn't activate at 200 degrees.

The bubbles come even when the engine is cold. They have smoke in them I believe. It starts before the radiator starts steaming and leaks out the water that is in it.

I will try your suggestions tomorrow.

And thanks for your input.
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post #6 of 7 Old 04-08-2020, 03:15 PM
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The fan fuse is After the ignition key, so only HOT when key is on. If not Hot when key is on, open circuit in the BROWN wire between.

Cooling fan Switch may need to be heated to as much as 214F to switch on!

Quit worrying about the bubbles for a bit. Of course the water or coolant will Expand with the radiator cap Removed. Thats Normal. Thats why we use a pressure cap.

pdwestman
Modify at "YOUR OWN RISK"!

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post #7 of 7 Old 04-08-2020, 06:42 PM
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When you attempted to test the fan switch in the kettle of water on top of the stove, did you not see some bubbles before the water got up to 212F?
I usually do, if I'm watching. Oops, you didn't even get that high.

The coolant pump impeller could also cavitate and cause some bubbles, imo.

pdwestman
Modify at "YOUR OWN RISK"!

Still riding my 1987 KL650-A1. 85,000+ miles & counting
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