Pinpointing a coolant leak

thestew42 · May 18th, 2015, 08:00 PM

Hi everyone, I need some help finding a coolant leak. I did a valve adjustment over the weekend along with some other stuff based on some of the great DIY articles here, but I have a problem now with a coolant leak. After finishing with the valves, I re-filled the coolant and started the bike to bleed the air from the system. When I did that, there was a leak of a drop every few seconds at one of the hose clamps behind the radiator cap (the hose that goes to the back of the engine). I tightened that one and it seemed to fix the problem.

Well after riding to work and back today about 50 miles, I took a look to make sure everything was good, but spotted that coolant had dripped over the clutch cover. It must be a slow leak because there isn't much there and I rode it for probably an hour. The problem is I can't figure out where it is coming from. I noticed a couple drops on the coolant reserve tank, so I'm guessing somewhere there but I can't be sure. I tried running it while warmed up with the fairing off to spot the leak, but no luck.

Does anyone have any ideas on where the leak is? Pictures are below, you'll see where the majority of it is on the clutch cover and a couple drops on the coolant tank. I didn't really notice any coming directly from any of the hoses. Thanks!

thestew42 · May 19th, 2015, 07:22 AM

So I remember that last night after turning the bike off, there was a short gurgling sound near the radiator cap. It sounded like a couple of bubbles, so I thought there might be an air bubble still in there. This morning I opened up the radiator cap and sure enough the coolant was low, so I added probably 4 oz or so to fill it back up, which seems like more than it leaked.

It's possible that I didn't bleed the system of air correctly, since this is my first time doing this. Is the cause of the leak, or just a symptom from losing coolant?

Motofool · May 19th, 2015, 08:35 AM

When working in the head, the o-ring sealing the tube that brings coolant into the head frequently starts leaking.
Nothing should be wrong with the rest of the coolant circuit.

thestew42 · May 20th, 2015, 07:18 PM

Thanks for the suggestion. I starting taking everything apart to get to that tube, and when I went to remove the coolant overflow tank, I noticed the cap wasn't threaded on correctly

Too bad I had already drained the coolant. It seems to be fine now.

dcj13 · May 20th, 2015, 07:35 PM

Best possible outcome!

May 18th, 2015, 08:00 PM	#1
thestew42 ninjette.org newbie Name: Stewart Location: San Diego Join Date: May 2015 Motorcycle(s): 2009 Ninja 250R Posts: 6	Pinpointing a coolant leak Hi everyone, I need some help finding a coolant leak. I did a valve adjustment over the weekend along with some other stuff based on some of the great DIY articles here, but I have a problem now with a coolant leak. After finishing with the valves, I re-filled the coolant and started the bike to bleed the air from the system. When I did that, there was a leak of a drop every few seconds at one of the hose clamps behind the radiator cap (the hose that goes to the back of the engine). I tightened that one and it seemed to fix the problem. Well after riding to work and back today about 50 miles, I took a look to make sure everything was good, but spotted that coolant had dripped over the clutch cover. It must be a slow leak because there isn't much there and I rode it for probably an hour. The problem is I can't figure out where it is coming from. I noticed a couple drops on the coolant reserve tank, so I'm guessing somewhere there but I can't be sure. I tried running it while warmed up with the fairing off to spot the leak, but no luck. Does anyone have any ideas on where the leak is? Pictures are below, you'll see where the majority of it is on the clutch cover and a couple drops on the coolant tank. I didn't really notice any coming directly from any of the hoses. Thanks!

May 19th, 2015, 08:35 AM	#3
Motofool Daily Ninjette rider Name: Hernan Location: Florida Join Date: Mar 2011 Motorcycle(s): 2007 Ninja 250 Posts: A lot. MOTY - 2016, MOTM - Dec '12, Jan '14, Jan '15, May '16	When working in the head, the o-ring sealing the tube that brings coolant into the head frequently starts leaking. Nothing should be wrong with the rest of the coolant circuit. __________________________________________________ *Motofool* *.................................Never ride faster than your guardian angel can fly* "Mankind is composed of two sorts of men — those who love and create, and those who hate and destroy. Love is the bond between men, the way to teach and the center of the world." - José Martí

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May 19th, 2015, 07:22 AM	#2
thestew42 ninjette.org newbie Name: Stewart Location: San Diego Join Date: May 2015 Motorcycle(s): 2009 Ninja 250R Posts: 6	So I remember that last night after turning the bike off, there was a short gurgling sound near the radiator cap. It sounded like a couple of bubbles, so I thought there might be an air bubble still in there. This morning I opened up the radiator cap and sure enough the coolant was low, so I added probably 4 oz or so to fill it back up, which seems like more than it leaked. It's possible that I didn't bleed the system of air correctly, since this is my first time doing this. Is the cause of the leak, or just a symptom from losing coolant?

May 20th, 2015, 07:18 PM	#4
thestew42 ninjette.org newbie Name: Stewart Location: San Diego Join Date: May 2015 Motorcycle(s): 2009 Ninja 250R Posts: 6	Thanks for the suggestion. I starting taking everything apart to get to that tube, and when I went to remove the coolant overflow tank, I noticed the cap wasn't threaded on correctly Too bad I had already drained the coolant. It seems to be fine now.

May 20th, 2015, 07:35 PM	#5
dcj13 Participant Name: Dave Location: South of Seattle Join Date: Oct 2012 Motorcycle(s): '94 K75 std Posts: Too much. MOTM - Aug '15	Best possible outcome!