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Discussion Starter · #1 ·
I was riding home from work yesterday and the bike temperature went up and up and up, it would come back down but eventually with traffic the red check engine light came on and HI was displayed in the temperature gauge. It has never even gotten remotely hot before & I have the fan set at 85/90 with Woolich and it was working but the temperature still went up? Is this normal on ZX10R's ?

Today I changed the oil & filter which looked fine and flushed the radiator and changed the coolant which was only 5 months old & that looked normal as well.

I was using a map I have used countless times before with no problems & which usually runs at 72c but yesterday I saw 117c in traffic. The air temperature was probably 36c which isn't that high for where I live in Brisbane, it's usually 32c everyday.

The bike ran fine the entire time, even when I stopped at a fuel station to fill up and the red light came on it started 1st time and then the temperature dropped back to 90c in the last 6kms until I got home.

Is this normal? Considering it usually runs at 72c it is a considerable jump, No radiator guard to cut the air flow either. I just don't like seeing the red light which means stop & pull over or you might be doing engine damage on my normal ride to work which consists of 90% highway at 100km/h. A bit of traffic and it is hot as hell. I saw the coolant in the overflow bubbling/boiling when I was stopped at the fuel station.

Will see how it runs tomorrow with new oil, filter, coolant, standard map & added 3% fuel to the standard Kawasaki Full power map.

Cheers for any help
 

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OK, so you have a problem.

No, that is NOT normal at all! You have other issues going on with the cooling system and you shouldn't ride it any more until that gets resolved. So, I'll put on my instructor hat and lecture everyone reading this on what is happening. Bear with me, or you're welcome to audit my class. :p:geek:

A liquid cooled engine uses water in the cylinder jackets to keep the temps down. Under standard atmosphere conditions, water boils at 212 deg F (100 deg C) and freezes at 32 deg F (0 deg C). A chemical is added to the water to prevent corrosion and lubrication on the metal parts and lower the freezing point down. You can't raise the boiling point of it the same way. To raise the boiling point, you have to increase the pressure on it. As the water heats up, the pressure increases and the boiling point goes up slightly. That assumes the expansion can be constrained so the pressure increases. Remember from your grade school science class, water can boil at room temp if the pressure is lowered in a vacuum and will boil at much higher temps under pressure. That's how pressure cookers work.

Now that the science lesson is done, your bike should not be getting that hot at all. You boiled the coolant in the reservoir so you've put air in the system. You need to take the cap off and vent the system and add more coolant to the radiator to remove all the air out and set the level correctly. That can't be done at the reservoir. With air in the system, the coolant will boil much quicker and at lower temps. And it won't cool the engine properly. It's a repeating cycle.

You had an issue that caused it to happen in the first place. Your map is only a small contributing factor to that. Idle speed and how long you spent above idle in traffic is the bigger issue. You need ariflow over the radiator to transfer the heat away from the coolant. Turning the bike off doesn't really help either unless it's for extended periods since the coolant stops circulating and the hot water sits in the radiator and cylinders. The fan kicks on early with the reflash to help, but that can only move so much air. You should sit stationary at idle with the fan running instead of moving slowly forward at 2-3,000 rpm if you can avoid it.

The radiator cap is what seals the system and keeps the pressure up. Most engine overheats are caused by a faulty cap, incorrect coolant level (air) in the system, or blocked passages in the radiator core. The fact that it got up to the 240 deg F warning for the 'HI' indication means you overheated the motor. The oil is now suspect and hopefully the cylinder head didn't warp. Serious issues happen at that point.

First thing to do is the coolant purge. Next would be a new radiator cap. After that if it still happens, then you're going to have to start tearing into the motor more aggressively to resolve it. Cooling issues are tough to the diagnose and fix sometimes.
 

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+1 something is wrong.
Maybe thermostat fail or pump.
Check if coolant circulates...cold engine, without cap, you should see coolant flow from small tube into radiator.
 

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I don't know how hot it actually got, but from experience the increase in engine heat is noticeable, you say that the engine was 100% running normal, well normally but not 100% the case if the engine gets that hot then it will run a little lumpy as the AFR tends to richen up a little. As with other comments above you have a problem but it maybe your temperature sensor on the way out.
 

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Discussion Starter · #5 ·
I Googled it and the temperature sensor can be the issue....

After changing all the fluids I let it idle with the cap off for a good 30 minutes and it took all of that to reach 90c and then the fan took it back to 84c

If there was any air in surely that would of released it. But it was the same setup for 5 months without issue.

The radiator cap is tight as to get on so I would assume the spring is good and the rubber looked fine.

Where is this temperature sensor hiding?

Thanks for the help
 

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I Googled it and the temperature sensor can be the issue....

After changing all the fluids I let it idle with the cap off for a good 30 minutes and it took all of that to reach 90c and then the fan took it back to 84c

If there was any air in surely that would of released it. But it was the same setup for 5 months without issue.

The radiator cap is tight as to get on so I would assume the spring is good and the rubber looked fine.

Where is this temperature sensor hiding?

Thanks for the help
It's located on the back side of cylinder 3 next to and inboard of the thermostat housing.
 

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Discussion Starter · #7 ·
Hang on..... a faulty temperature sensor won't make the coolant bubble or boil in the overflow tank.

Another piece of information just came to me. When I removed the drain plug on the coolant and still had the radiator cap on nothing came out & I thought there you go there must be a leak. So I did the oil change and filter. While I was doing that I squeezed a radiator hose and the coolant came out, another squeeze and more coolant. Then I took the radiator cap off and it came pouring out. 2.6 litres is the capacity and it was definitely 2.6lt.

I am thinking radiator cap, I have had my old muscle car do a similar thing years ago and the cap looked fine but that fixed the car.

I was going to ride it today but maybe I will take the Yamaha and buy a new cap.
 

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Discussion Starter · #8 ·
Also about a month ago the overflow tank went from Full to really full so I unplugged the bottom hose on the overflow for about 10 seconds to drop it back to full. Would that have introduced air into the system? It couldn't of, as soon as the hose was off the coolant poured out & it was only seconds before the hose was reconnected.

It's more information.
 

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Hang on..... a faulty temperature sensor won't make the coolant bubble or boil in the overflow tank.

Another piece of information just came to me. When I removed the drain plug on the coolant and still had the radiator cap on nothing came out & I thought there you go there must be a leak. So I did the oil change and filter. While I was doing that I squeezed a radiator hose and the coolant came out, another squeeze and more coolant. Then I took the radiator cap off and it came pouring out. 2.6 litres is the capacity and it was definitely 2.6lt.

I am thinking radiator cap, I have had my old muscle car do a similar thing years ago and the cap looked fine but that fixed the car.

I was going to ride it today but maybe I will take the Yamaha and buy a new cap.
You are correct. The sensor wouldn't cause the coolant to boil over. But now you know where the sensor is located. ;)

The drain plug out, it will just drip out slightly until the cap is off. It won't drain without the cap off to let air in the system. There's a suction on the system at that point. Drain plug out, cap off, and she'll piss coolant out pretty quickly. So with the cap on and drain plug out, if there was a leak then it will start draining slowly.
 

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Discussion Starter · #11 ·
You are correct. The sensor wouldn't cause the coolant to boil over. But now you know where the sensor is located. ;)

The drain plug out, it will just drip out slightly until the cap is off. It won't drain without the cap off to let air in the system. There's a suction on the system at that point. Drain plug out, cap off, and she'll piss coolant out pretty quickly. So with the cap on and drain plug out, if there was a leak then it will start draining slowly.
So would that suggest there was no air in the system? Thus Pointing more to the radiator cap being the problem?
 

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Also about a month ago the overflow tank went from Full to really full so I unplugged the bottom hose on the overflow for about 10 seconds to drop it back to full. Would that have introduced air into the system? It couldn't of, as soon as the hose was off the coolant poured out & it was only seconds before the hose was reconnected.

It's more information.
That may have triggered it. The bottom hose fills the reservoir from the bottom up. The top hose loops down to the ground to vent an overfill. If you took the hose off the bottom, then you put air in the small hose. If the engine was still cooling down and the coolant shrinks, then it will recoup the coolant from the reservoir. If there was an air gap in there, that's what got pulled in. A few tiny bubbles (no, not the song) is all it would take to start the process. Never drain the resevoir that way unless the engine is cold. And it's better to suction it out or flip the bottle over and empty it that way.

 

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So would that suggest there was no air in the system? Thus Pointing more to the radiator cap being the problem?
Yeah, it would indicate a good seal on the system. But even opening up the drain would put air in the system near the pump. If that's removed, then the system should be purged even if the coolant is reused. Burp the lines and overfill the radiator.

Sensor part number is: 21176-0009
 

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Discussion Starter · #14 ·
That may have triggered it. The bottom hose fills the reservoir from the bottom up. The top hose loops down to the ground to vent an overfill. If you took the hose off the bottom, then you put air in the small hose. If the engine was still cooling down and the coolant shrinks, then it will recoup the coolant from the reservoir. If there was an air gap in there, that's what got pulled in. A few tiny bubbles (no, not the song) is all it would take to start the process. Never drain the resevoir that way unless the engine is cold. And it's better to suction it out or flip the bottle over and empty it that way.

Thankyou. So that probably answers the entire issue? Don't need anything. I inadvertently introduced air into the system?

I did buy a pump to pump out fluids on Ebay but naturally it doesn't work or I would of taken the fluid out of the top lid. Bloody Ebay!
 

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Thankyou. So that probably answers the entire issue? Don't need anything. I inadvertently introduced air into the system?

I did buy a pump to pump out fluids on Ebay but naturally it doesn't work or I would of taken the fluid out of the top lid. Bloody Ebay!
At this point, I would go with that assumption. Based on what you describe, that's where I would start. Purge and refill the whole system to get any air out. Change the oil for good measure since it was overheated in the process. Then button her back up and see what you get. If it's all normal, then that was the issue. If it happens again, you can troubleshoot it from there.
 

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Discussion Starter · #16 ·
At this point, I would go with that assumption. Based on what you describe, that's where I would start. Purge and refill the whole system to get any air out. Change the oil for good measure since it was overheated in the process. Then button her back up and see what you get. If it's all normal, then that was the issue. If it happens again, you can troubleshoot it from there.
Yes, all that is done, new oil, filter, flushed radiator and brand new coolant, I let it idle without the cap on for 30 minutes yesterday and that would of spat out any air in the system?

Thanks for your/everyones help in solving this. I am going for a ride soon so I will find out if it's cured.

Cheers

Ash
 

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Discussion Starter · #19 ·
On the ride home, sat on 72c so definately fixed. I love the internet for things like this. I would of fixed it by changing the coolant and oil but I would never have known why it overheated in the first place and would be changing out parts just in case! Hate to even think if I took it to a dealer, new thermostat, new radiator, $2000 bill.......

Thanks again!

Cheers
 

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On the ride home, sat on 72c so definately fixed. I love the internet for things like this. I would of fixed it by changing the coolant and oil but I would never have known why it overheated in the first place and would be changing out parts just in case! Hate to even think if I took it to a dealer, new thermostat, new radiator, $2000 bill.......

Thanks again!

Cheers
Yes this thread is a good example of just that, 2 folks banged it out. SkyDork the legend continues :geek:
 
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