Completely normal? Or is this a problem...

Socal5646 · September 21st, 2011, 07:58 PM

So I took the bike out for a longer trip than normal about 40 miles (usually travel a fe miles each direction)....upon arriving at the parking lot (granted I was idling for 3-5 min max) the temp was almost in the red and there was coolant gushing out of the overflow tube at the bottom of the bike. I just shut it off parked it and went about my business. When I got back...2hrs later...it was cold, started up just fine, and had no problem getting home!

So my question is....if this is normal, can I avoid this in the future somehow? If it isn't normal....any ideas what I'm facing?

choneofakind · September 21st, 2011, 08:04 PM

I've never looked at my coolant level right after shutting it off, but my bike does heat up quite nicely when it idles. I've never had it up to the red line on the temp gauge though.

Alex · September 21st, 2011, 08:16 PM

You had it sitting idling for 3 - 5 minutes after the ride? These bikes (and most bikes) aren't great at idling long-term; their cooling systems are designed to be effective when the bike is in motion. That said, for coolant to start pouring out after only 5 minutes does sound a little early. I'd make sure that your cooling fan is turning on at all. It isn't needed much when the bike is in motion, but if the bike is parked, idling, and the fan isn't coming on, it could cause this.

Socal5646 · September 21st, 2011, 08:23 PM

Yeah....I was sitting there trying to convince the parking guy not to charge me full price...=). I was thinking it may be an issue with the fan....how can I test if its functioning properly? I have to admit, when I saw the coolant pouting out, I panicked and shut it off without looking/listening for any symptoms...

bluepoof · September 21st, 2011, 08:26 PM

My pregen does this at the end of every summertime ride that ends at my house (I live on a one lane hill, so the ride ends with lots of low-gear slow speed riding). Can you hear it bubbling over? Weird sound, huh.

I dunno, I don't worry about it too much, but maybe that's me being naive as none of my other bikes have ever done this.

It's only an issue for me if I accidentally overfill the reservoir because then I have a mess to clean up. Otherwise it's just a creepy noise and a few drops on the ground.

Alex · September 21st, 2011, 08:31 PM

Quote:

Originally Posted by Socal5646

I was thinking it may be an issue with the fan....how can I test if its functioning properly?

If the temp gauge is in the red zone, the fan should be on (and you should be able to hear it). But even easier, if you turn off the bike, the fan should still be running for a few moments (a minute or two) afterwards if the bike truly was that hot.

If it's boiling over, and when you turn the bike off you're not hearing a fan, something isn't working as designed. Either the temp sensor that triggers the fan (unlikely if the gauge is still working properly), or the fan mechanism itself. Sometimes it can be something as simple as a rock that gets in there and kept the fan from turning once, which blows the fuse.

Socal5646 · September 21st, 2011, 08:41 PM

Quote:

Originally Posted by bluepoof

My pregen does this at the end of every summertime ride that ends at my house (I live on a one lane hill, so the ride ends with lots of low-gear slow speed riding). Can you hear it bubbling over? Weird sound, huh.

I dunno, I don't worry about it too much, but maybe that's me being naive as none of my other bikes have ever done this.

It's only an issue for me if I accidentally overfill the reservoir because then I have a mess to clean up. Otherwise it's just a creepy noise and a few drops on the ground.

This was WAY more than a few drops! I mean it was gushing! I thought I had a broken hose before I saw it was coming out of the overflow tube....

Socal5646 · September 21st, 2011, 08:42 PM

Quote:

Originally Posted by Alex

If the temp gauge is in the red zone, the fan should be on (and you should be able to hear it). But even easier, if you turn off the bike, the fan should still be running for a few moments (a minute or two) afterwards if the bike truly was that hot.

If it's boiling over, and when you turn the bike off you're not hearing a fan, something isn't working as designed. Either the temp sensor that triggers the fan (unlikely if the gauge is still working properly), or the fan mechanism itself. Sometimes it can be something as simple as a rock that gets in there and kept the fan from turning once, which blows the fuse.

Gonna go chek the fuse and jump the fan....I'll check in in a few...

Socal5646 · September 21st, 2011, 08:49 PM

Quote:

Originally Posted by bluepoof

: It's only an issue for me if I accidentally overfill the reservoir because then I have a mess to clean up. Otherwise it's just a creepy noise and a few drops on the ground.

So where do you fill your reservoir to? The "L" mark?

bluepoof · September 21st, 2011, 09:11 PM

Quote:

Originally Posted by Socal5646

This was WAY more than a few drops! I mean it was gushing! I thought I had a broken hose before I saw it was coming out of the overflow tube....

Oh, mine gushes too, if the reservoir is above the midline.

bluepoof · September 21st, 2011, 09:11 PM

Quote:

Originally Posted by Socal5646

So where do you fill your reservoir to? The "L" mark?

You're "supposed" to fill it to the F (as per the Haynes manual) but that makes mine spill all over. I generally fill it to about halfway between the L and F.

choneofakind · September 21st, 2011, 09:40 PM

Quote:

Originally Posted by Socal5646

I was sitting there trying to convince the parking guy not to charge me full price...=)

the truly important question here; Did you get the parking discount??

Socal5646 · September 21st, 2011, 10:05 PM

Negative...bastard charged me the full 15 bucks! But I did leave a nice pool of coolant in front of his little hut...=)

Socal5646 · September 21st, 2011, 10:08 PM

Quote:

Originally Posted by bluepoof

Oh, mine gushes too, if the reservoir is above the midline.

So I take it, you top it off every time this happens? Cause I just checked my res and it's empty (bike cold)....when it was gushing and I shut it off, I took the seat off and it was just above "L"

Thanks for all the help btw...=)

CmichRider · September 21st, 2011, 10:25 PM

I don't remember reading it, but the coolant should be just about L when the bike is cold, and get up the F when it's warmed up. Don't quote me on that tho, but if you're filling to the F when the bike is cold, and if the coolant expands when it gets hot, it will overflow the reservoir.

FrugalNinja250 · September 22nd, 2011, 08:09 AM

Coolant volume expands and contracts as the engine goes through its normal thermal cycles. When fully warmed up, the coolant level should be at the full mark on the reservoir, which is
where the coolant goes as it expands inside the engine and radiator.

Pure water boils at 212 degrees at sea level, mixed with antifreeze in the preferred ratio of 50-50 that temperature rises to about 230 degrees. Though the coolant temperature going through the thermostat may be lower than the boiling point, there will be localized hot spots in the cylinder head where the coolant may be 250 degrees or higher. When water boils it flashes to steam, creating a sudden pressure spike in the process. That pressure spike and steam bubble pushes coolant out of the system, into the coolant reservoir, and then out through the reservoir's overflow tube.

The radiator cap has a two way pressure relief valve built into it. When the coolant heats and expands it creates pressure inside the cooling system. The radiator cap resists this pressure up to around 15 psi, causing the presssure in the system to rise and stay at that pressure. At 15psi the boiling temperature of the coolant rises to almost 270 degrees with 50% ethylene glycol.

When the coolant temperature drops the volume shrinks. The radiator cap's other valve opens at zero pressure difference and allows coolant to be sucked back into the system from the overflow reservoir.

It is not normal to lose coolant under any circumstances. Engineers go to great efforts in design and testing to ensure this.

A faulty radiator cap will prevent pressure from building, thus allowing steam pockets to form in the cooling passages in the head; these will block coolant flow and cause localized overheating. At higher RPMs and speeds enough heat is removed from the coolant that the much cooler coolant causes the steam bubbles to collapse, allowing some flow before the next cycle of steam pocket formation. A clogged radiator could also cause this, as well as a faulty coolant pump.

Most thermostats that I've dealt with seemed to fail in the closed position, causing overheating. The symptoms were that at idle the engine would start overheating rapidly, but revving the engine would cool it off because of the extra coolant flow past the partially closed thermostat at higher RPMs. It gets worse and worse until it completely overheats and blows coolant out the overflow reservoir.

September 21st, 2011, 07:58 PM	#1
Socal5646 ninjette.org member Name: John Location: Los Angeles Join Date: Sep 2011 Motorcycle(s): 2011 150cc chinaman scooter Posts: 226	Completely normal? Or is this a problem... So I took the bike out for a longer trip than normal about 40 miles (usually travel a fe miles each direction)....upon arriving at the parking lot (granted I was idling for 3-5 min max) the temp was almost in the red and there was coolant gushing out of the overflow tube at the bottom of the bike. I just shut it off parked it and went about my business. When I got back...2hrs later...it was cold, started up just fine, and had no problem getting home! So my question is....if this is normal, can I avoid this in the future somehow? If it isn't normal....any ideas what I'm facing?

September 21st, 2011, 08:16 PM	#3
Alex ninjette.org dude Name: 1 guess :-) Location: SF Bay Area Join Date: Jun 2008 Motorcycle(s): '13 Ninja 300 (white, the fastest color!), '13 R1200RT, '14 CRF250L, '12 TT-R125LE Posts: Too much. Blog Entries: 7	You had it sitting idling for 3 - 5 minutes after the ride? These bikes (and most bikes) aren't great at idling long-term; their cooling systems are designed to be effective when the bike is in motion. That said, for coolant to start pouring out after only 5 minutes does sound a little early. I'd make sure that your cooling fan is turning on at all. It isn't needed much when the bike is in motion, but if the bike is parked, idling, and the fan isn't coming on, it could cause this. __________________________________________________ Montgomery Street Motorcycle Club / cal24.com / crf250l.org / ninjette.org ninjette.org Terms of Service Shopping for motorcycle parts or equipment? Come here first. The friendliest Ninja 250R/300/400 forum on the internet! (especially Unregistered)

September 21st, 2011, 08:26 PM	#5
bluepoof ninjette.org sage Name: Carolyn Location: San Carlos, CA Join Date: Nov 2010 Motorcycle(s): 2007 Ninja 250, 2002 Yamaha XT225 Posts: 597	My pregen does this at the end of every summertime ride that ends at my house (I live on a one lane hill, so the ride ends with lots of low-gear slow speed riding). Can you hear it bubbling over? Weird sound, huh. I dunno, I don't worry about it too much, but maybe that's me being naive as none of my other bikes have ever done this. It's only an issue for me if I accidentally overfill the reservoir because then I have a mess to clean up. Otherwise it's just a creepy noise and a few drops on the ground. __________________________________________________ www.bluepoof.com

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September 21st, 2011, 08:04 PM	#2
choneofakind ninjette.org certified postwhore Name: . Location: . Join Date: Feb 2011 Motorcycle(s): . Posts: Too much. MOTM - Feb '13, Feb '14	I've never looked at my coolant level right after shutting it off, but my bike does heat up quite nicely when it idles. I've never had it up to the red line on the temp gauge though.

September 21st, 2011, 08:23 PM	#4
Socal5646 ninjette.org member Name: John Location: Los Angeles Join Date: Sep 2011 Motorcycle(s): 2011 150cc chinaman scooter Posts: 226	Yeah....I was sitting there trying to convince the parking guy not to charge me full price...=). I was thinking it may be an issue with the fan....how can I test if its functioning properly? I have to admit, when I saw the coolant pouting out, I panicked and shut it off without looking/listening for any symptoms...

September 21st, 2011, 10:05 PM	#13
Socal5646 ninjette.org member Name: John Location: Los Angeles Join Date: Sep 2011 Motorcycle(s): 2011 150cc chinaman scooter Posts: 226	Negative...bastard charged me the full 15 bucks! But I did leave a nice pool of coolant in front of his little hut...=)

September 21st, 2011, 10:25 PM	#15
CmichRider ninjette.org member Name: Jacob Location: Michigan Join Date: Mar 2011 Motorcycle(s): 2000 Ninja 250 Posts: 227	I don't remember reading it, but the coolant should be just about L when the bike is cold, and get up the F when it's warmed up. Don't quote me on that tho, but if you're filling to the F when the bike is cold, and if the coolant expands when it gets hot, it will overflow the reservoir.

September 22nd, 2011, 08:09 AM	#16
FrugalNinja250 ninjette.org certified postwhore Name: Frugal Location: Dallas/Fort Worth (DFW) Join Date: Mar 2010 Motorcycle(s): Several Posts: A lot.	Coolant volume expands and contracts as the engine goes through its normal thermal cycles. When fully warmed up, the coolant level should be at the full mark on the reservoir, which is where the coolant goes as it expands inside the engine and radiator. Pure water boils at 212 degrees at sea level, mixed with antifreeze in the preferred ratio of 50-50 that temperature rises to about 230 degrees. Though the coolant temperature going through the thermostat may be lower than the boiling point, there will be localized hot spots in the cylinder head where the coolant may be 250 degrees or higher. When water boils it flashes to steam, creating a sudden pressure spike in the process. That pressure spike and steam bubble pushes coolant out of the system, into the coolant reservoir, and then out through the reservoir's overflow tube. The radiator cap has a two way pressure relief valve built into it. When the coolant heats and expands it creates pressure inside the cooling system. The radiator cap resists this pressure up to around 15 psi, causing the presssure in the system to rise and stay at that pressure. At 15psi the boiling temperature of the coolant rises to almost 270 degrees with 50% ethylene glycol. When the coolant temperature drops the volume shrinks. The radiator cap's other valve opens at zero pressure difference and allows coolant to be sucked back into the system from the overflow reservoir. It is not normal to lose coolant under any circumstances. Engineers go to great efforts in design and testing to ensure this. A faulty radiator cap will prevent pressure from building, thus allowing steam pockets to form in the cooling passages in the head; these will block coolant flow and cause localized overheating. At higher RPMs and speeds enough heat is removed from the coolant that the much cooler coolant causes the steam bubbles to collapse, allowing some flow before the next cycle of steam pocket formation. A clogged radiator could also cause this, as well as a faulty coolant pump. Most thermostats that I've dealt with seemed to fail in the closed position, causing overheating. The symptoms were that at idle the engine would start overheating rapidly, but revving the engine would cool it off because of the extra coolant flow past the partially closed thermostat at higher RPMs. It gets worse and worse until it completely overheats and blows coolant out the overflow reservoir.