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Discussion Starter · #21 ·
also to respond to yorkie's quesion: reservoir is empty this morning.
Also another thing I noticed -- when i took cap off radiator, it took very little to top it off, which means the coolant that got thrown out of the overflow hose was the coolant that had been in the reservoir yesterday.
 

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Discussion Starter · #22 ·
Simple test to see if the fan is or is not your problem. fill the coolant system, run the engine at full throttle, see if coolant bubbles up into the expansion tank even when cool.
or open the rad cap and watch the coolant as you blip the throttle to full see bubbles?.
What you have is compression gasses escaping into the cooling system over pressurizing it. even when cold.

= warped head = lapp the head
Fan is a white elephant, but fix it anyway while your lapping the head

FOG
Alright I'll try this when I get back.
 

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Cheers! Saw your solution on Kawasaki Forums, blown fuse.

You knew: "I bet there's a fuse thats busted" above at Comment #3, 19 hours ago! Did you know there's an easier way to check fuses? Just sayin'...

Glad it's sorted, enjoy the ride!
 

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Discussion Starter · #24 ·
Cheers! Saw your solution on Kawasaki Forums, blown fuse.

You knew: "I bet there's a fuse thats busted" above at Comment #3, 19 hours ago! Did you know there's an easier way to check fuses? Just sayin'...

Glad it's sorted, enjoy the ride!
Haha, yeah I realized I didn't have to use a multimeter when I pulled it out.
 

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Discussion Starter · #25 ·
So I just got back from the ride. Needle did same thing as yesterday, and fan never came on. This time I didn't let it touch red but it got real close and fan didn't budge. So next step is testing thermostat to hopefully find out why fan isn't turning on when it gets hot.
 

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What was the outside temp on todays ride?
 

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Discussion Starter · #28 ·
The reason I say that is: if I understand correctly, thermostat regulates coolant traveling between engine block and radiator. If it's broken, that back and forth flow won't happen when it should and it could lead to it overheating. The switch in turn regulates power to fan, so since fan works but isn't turning on when it should, the switch might be a culprit.
 

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Here is what I would do, if it was my bike.
OP must decide because you are the only one with hands on experience with the bike.

1. replace thermostat & thermostat housing o-ring.
2. replace switch 27010-1304 or K&L replacement part (less expensive).
3. Once everything is reassembled, Fill & Burp cooling system. Fill and Burp: remove Radiator Cap, pour coolant (Honda coolant in bottle is already 50-50 antifreeze and water) until the level is all the way to the top. Then squeeze hoses slowly, watch level go down; repeat pour coolant to top level, squeeze hoses, especially hose on right side of engine, and especially the two hoses from the top of the engine to the thermostat housing. Keep doing that until you get no more level going down. Then you've burped the cooling system of all or most of the air. Replace radiator cap. Pour coolant into overflow tank to somewhere between Low and Full, mark it with a magic marker. Start & run engine, inspect for leaks. Drive around the block a few times reach operating temperature, return home, let engine idle in driveway, wait for fan to come on. let fan run for a minute then shut down engine. Allow engine to cool, then check coolant level in overflow tank; add some coolant if necessary, but do not overfill, somewhere between Low and Full is plenty.
 

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Discussion Starter · #30 ·
Here is what I would do, if it was my bike.
OP must decide because you are the only one with hands on experience with the bike.

1. replace thermostat & thermostat housing o-ring.
2. replace switch 27010-1304 or K&L replacement part (less expensive).
3. Once everything is reassembled, Fill & Burp cooling system. Fill and Burp: remove Radiator Cap, pour coolant (Honda coolant in bottle is already 50-50 antifreeze and water) until the level is all the way to the top. Then squeeze hoses slowly, watch level go down; repeat pour coolant to top level, squeeze hoses, especially hose on right side of engine, and especially the two hoses from the top of the engine to the thermostat housing. Keep doing that until you get no more level going down. Then you've burped the cooling system of all or most of the air. Replace radiator cap. Pour coolant into overflow tank to somewhere between Low and Full, mark it with a magic marker. Start & run engine, inspect for leaks. Drive around the block a few times reach operating temperature, return home, let engine idle in driveway, wait for fan to come on. let fan run for a minute then shut down engine. Allow engine to cool, then check coolant level in overflow tank; add some coolant if necessary, but do not overfill, somewhere between Low and Full is plenty.
This is pretty much what I was planning on doing, I ordered thermostat & switch on ebay earlier today when I realized they were only $30 total. They'll be here in about a week so I'll post with what happens in case folks are curious.
 

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If it's broken, that back and forth flow won't happen when it should and it could lead to it overheating.
Actually there are two ways for the thermostat to break. The most common way is for the valve to stick open. When this happens the vehicle has a hard time (sometimes even impossible) to warm up to operating temperature. This can easily be seen just by a visual check.
The less common way for the thermostat to break would be for the valve to stick in the closed position. A lot of times this too can be seen with a visual check (damaged spring).
If you don't see any obvious damage on the thermostat, you can test it to see if it is properly operating. Suspend the thermostat in a pan of water using a wire. Also suspend a meat thermometer in the pan of water. Place the pan of water on a stove top, and heat the water up. Watch the thermostat, and when it opens, check the thermometer to see what the temperature is. When the thermostat opens, the temperature should be between 177*~182*.
I'll post with what happens in case folks are curious.
We're all curious, keep us updated. (y)
 
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This is pretty much what I was planning on doing, I ordered thermostat & switch on ebay earlier today when I realized they were only $30 total. They'll be here in about a week so I'll post with what happens in case folks are curious.
thanks for the update. if it's any interest here we have started getting colder temps with morning ground frosts, average temperature is 7degrees C (44.6F) so (while working in the garage) this morning I pulled the gen 1 out for a pre winter inspection, this included a heat cycle.
starting from cold @ 1200rpm idle it took 2mins 40sec to move the gauge off cold, 4mins 15sec to reach normal (about half gauge) by 7mins 30 it reached 3/4 gauge and the fan came on, this ran for 2mins 20sec which returned the temp back to half gauge and the fan turned off.
at which point I turned the engine off. so a total of 9mins 50sec to do a full heat cycle at 44.6 F (stationary)
yes the bike was stationary so had no (riding) airflow through the radiator. but how long would it have run past 7mins 30 sec to overheat without the fan running, I wonder, this is a bike with no cooling issues,
I am at pains to give in to the notion that all cooling issues are a blown head gasket unless all other avenues have been exhausted, lapping the head is a PITA because of the work involved and not everyone can do it. or have the equipment and tools to pull it off successfully.
check everything else first is my moto. you may end up having to do it anyway if everything checks out, but at least you will know the rest of the system is fully working and doing what it is supposed to do.
just my two cents worth.
 

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Obviously not all cooling issues are due to a warped head. It just depends on what the cooling issue is. What the symptoms are would most determine what the issue is.
Most of the cooling has to do with the bike being in motion. 8 months out of the year my fan never comes on, and most of that time the temp gauge never rises above the 1/2 way point. The year 2020 was the best fan relaxation year of all. Not once during the entire year did the fan come on, not even when it was above 95* outside. Of coarse due to there not being any traffic to deal with. Bear in mind I don't ride at high RPM's like a lot do. Riding at red line will make the bike run much hotter.
 
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while the thermostat regulates the engine temp ,by valving coolant to the radiator. the cap is what controls the flow to the expansion tank , it maintains the engine side at 13 PSI then valves any over pressure to the expansion tank. then as the engine cool allows the return to the engine through a separates valve.
The cap in far more important in this case. you need to discover the cause of the overpreasur. your case seems to me that it occurs before boiling, therefore bad head

FOG
 

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Yo had this same problem I replaced my thermostat and my radiator cap my cap had melted and blocked the coolant flow thermostat also wasn’t working properly you will have to change coolant as well
 

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to correctly identify your problem ,you must:
Determine if coolant overflows first then over heating occurs or:
engine overheats then overflow occurs.
Which it is determines your problem

FOG
 

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Obviously not all cooling issues are due to a warped head. It just depends on what the cooling issue is. What the symptoms are would most determine what the issue is.
Most of the cooling has to do with the bike being in motion. 8 months out of the year my fan never comes on, and most of that time the temp gauge never rises above the 1/2 way point. The year 2020 was the best fan relaxation year of all. Not once during the entire year did the fan come on, not even when it was above 95* outside. Of coarse due to there not being any traffic to deal with. Bear in mind I don't ride at high RPM's like a lot do. Riding at red line will make the bike run much hotter.
My fans on all the bikes usually do not come on. It has to be +90s and high speed runs and sometimes they will come on at the end of the ride. The bikes barely put any coolant into their bottles.
 

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I bought a 2009 ninja 500r a few weeks ago and about a week ago the temperature needle dipped up into the red. I pulled over, let it cool down and rode back home nice and easy. I was riding it in a city with some stoplights, and the temperature here is getting borderline chilly (around low 50s Fahrenheit when this happened). So it wasn't like a 90 degree day or anything
The last few days I did the following:
Flushed radiator with 50/50 vinegar and distilled water. The drain plug was clogged with brown sludge and the first two rinses came out dirty. Last rinse of 100% distilled water came out clear.
Disconnected & cleaned coolant reservoir.
Filled radiator with antifreeze/coolant I got from Autozone (this stuff here: https://www.autozone.com/antifreeze...year-150k-mile-protection-1-gallon/540721_0_0).
Burped radiator tubes, turned it on with radiator cap off til bubbles brought level down more, etc.
Filled coolant reservoir to between the two lines. (should I have ridden it first and then added coolant to reservoir?)
Took it out again today, and sure enough after about 20 minutes of city riding in the same cool weather, needle touches the red, and just as it does this, I hear a weird noise and it's throwing up a bunch of the coolant out of the overflow hose. I took a video of it, but it was the noise of whatever pushes the coolant out of the overflow hose.
The fan was not on -- it clearly should have been, but I honestly wonder if that would have made a huge difference, since the temperature was around 55 Fahrenheit and although I had sat at a few stoplights and wasn't riding super slow, I also wasn't gunning it or going super hard on it.
I let the bike cool down and rode it back home nice and easy, stopping a few times along the way to let it cool down.
The next steps I'm going to take are:
See if I can turn the fan on with a paper clip. If fan doesn't work, fix it, and try again.
If it continues overheating and throwing coolant out of the overflow hose, I'll see if thermostat is working properly.
Does anyone with more experience than me have any ideas of know what the issue is based on the above?
Thanks for any help,
Sidney
My 2002 EX500D is due for the cooling system total maintenance. Wouldn't a small electric pump be a lot less hassle? Replacement or service would seem to be less of a hassle.
 
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