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Perpetual Project
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3,695 Posts
Discussion Starter · #1 ·
My bike is wetting itself.:confused:

I've been having this issue with my coolant lately. If I sit in traffic for too long on a hot day I notice that it leaks coolant from the one hose/rad joint, runs down the hose and onto the ground. Not real good. It lowers the coolant level, but not a great deal, it seems to hit a certain level and not overflow any more. My overflow bottle is drained at this point, and if I re-fill the system it just happens all over again the next time I'm in traffic on a hot day.

My setup is an aluminum bottle, with 2 hoses: the overflow tube, which goes in the top and stops about 2 inches into the bottle, and the tube which connects to the radiator which goes clear to the bottom of the bottle. The bottle and all the hose/bottle connections are sealed because to my understanding the coolant system has to be pressurizing to work properly (correct?).

So obviously if I have any kind of overflow it should be out the "overflow" tube from the coolant resivior; so why is it overflowing and forcing its way out the joint between the radiator and the hose that feeds the coolant pump? Do I have my hoses rigged into the resiviour the wrong way? Should the resiviour be sealed or does that not matter?

More info: I checked the thermostat, its functioning in the right range. I checked the fan switch, its working, and working in the proper temp range as well.

Help a fighter out?:knucks:
 

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Member
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49 Posts
How old is the hose? It's possible to have a small pinhole that seeps fluid but is not noticeable by just looking at it. Sometimes you'll need to squeeze the hose while it's hot to see where coolant is leaking.

Also, post a shot of the hose/rad. joint & how it connects.

If it's just sealed with no clamps or anything, I'd probably replace it with a regular ole $1.00 metal hose clamp. With a properly sized hose, there is no better seal IMHO.
 

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Perpetual Project
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3,695 Posts
Discussion Starter · #5 ·
Bike is only 2 yrs old, so hoses are that, and fluid is new this season. The hoses all have hose clamps on them and they are deffinatly tightened down, that was the first thing I checked.

Theres a possibility there could be a pinhole in the hose, maybe scuffed up when I was putting the clamp on or something. I'll check that, but I'm 90% sure thats not it.

Other thoughts?

Can someone confirm the arrangement of the hoses is correct for me? i.e. overflow tube from resivior only goes in 2" and tube to radiator goes to the bottom of the resivior?
 

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Senior Member
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890 Posts
Your overflow set-up sounds OK to me. But it sounds like the radiator cap is not allowing fluid out for the overflow. And hence it is forcing it out through the rad hoses. Or maybe your overflow line is blocked??
 

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Perpetual Project
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3,695 Posts
Discussion Starter · #8 ·
I`ll see what I can do for pics tomorrow, I'll check for blockages in the lines too.
 

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Hawk GT's are Cool
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1,482 Posts
sounds good, i went from like a 28 oz overflow to a 8 oz, so mine pissed for awhile when it got hot sitting in traffic, not pissing anymore and temps are staying fine. Although it was a car issue ive had the tubes actually expand, but that issue was a bad water pump if i recall, and that was like 7 years ago, so dont quote me on that, but i have had similar happen to a car.
 

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is not your fucking bro
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7,216 Posts
this is all a theory. radiators are designed to overflow even if they dont have a tank. if your cap is rated to purge at 16 psi you fill it the enigne when warm will make 25 psi or so but it cant get there because it dumps at 16. you cannot compress a liquid so the system builds pressure and it blows out wherever it can till the system has enough air in it to hold around 16 psi. if your cap is stuck closed it will blow wherever it can. anytime that motor is running that water pump is turning and its trying to build pressure. so when it stops leaking its not because its done overflowing its because the system has enough air it can sustain 16 psi.
 

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Hawk GT's are Cool
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1,482 Posts
this is all a theory. radiators are designed to overflow even if they dont have a tank. if your cap is rated to purge at 16 psi you fill it the enigne when warm will make 25 psi or so but it cant get there because it dumps at 16. you cannot compress a liquid so the system builds pressure and it blows out wherever it can till the system has enough air in it to hold around 16 psi. if your cap is stuck closed it will blow wherever it can. anytime that motor is running that water pump is turning and its trying to build pressure. so when it stops leaking its not because its done overflowing its because the system has enough air it can sustain 16 psi.
Yeah bad caps can cause issues as well, and nice explantion koko. Where its leaking does that side go into the engine with the cooled coolant? When you changed your coolant last did it get a good flushing?
 

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Perpetual Project
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3,695 Posts
Discussion Starter · #13 ·
Yes the side that leaks goes into the pump and into the engine, and ya the system has had a pretty good purge over the corse of this year with as many times as I've drained it, refilled it, blew a hose once (loose clamp) ect.

I think I understand what you're saying there Chandler, but the thing I still don't get would be that even if it were to overflow, wouldn't the path of least resistance still be the resivior overflow? ... unless maybe theres not enough fluid in the reisvior to push up and out the overflow??? The overflow tube should not be down into the fluid in the resiviour normally right?

If it is a bad cap is there any way to check for that? Or do I just need to get a spare cap and try it? Dam I had a spare too with a junk rad I had and I threw it away...
 

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is not your fucking bro
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7,216 Posts
alot of radiator testers from like napa have an adapter for testing caps. just run in an auto shop and ask if someone will test it for a buck. id do it for a dollar. yes the path of least resistance is the overflow but if the cap isnt opening it wont be able to get there. the overflow is a two sided object. when the radiator has to much pressure it overflows to it but some caps have a valve in them so if the coolant in the radiator runs empty and draws a vaccuum, the vaccuum will draw coolant out of the overflow. thats why theres a tube in the overflow. you keep the coolant half full in the overflow so if it overflows it wont go full but if it goes dry it can suck some out.
 

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Function IS Form
19 Z900, 88 Kat11
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17,433 Posts
I've only read a couple posts here but Kokomo's right. With the cap not working, the overflow isn't going to fill at all.
 

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the mad doctor
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3,399 Posts
also, i've seen crap build up on coolant system joints alot of times. usually an easy fix by loosening the clamp, twisting the hose a few times to break up any corrosion, and retightening the clamp. this would especially be true if you've had the system apart a few times like you have. sometimes the corrosion can make a "trail" thru the joint, and when the pressure gets high enough, it'll leak.

how much of a leak are we talking here anyway?
 

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is not your fucking bro
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7,216 Posts
My setup is an aluminum bottle, with 2 hoses: the overflow tube, which goes in the top and stops about 2 inches into the bottle, and the tube which connects to the radiator which goes clear to the bottom of the bottle. The bottle and all the hose/bottle connections are sealed because to my understanding the coolant system has to be pressurizing to work properly (correct?).
on a setup with a radiator cap on the radiator the overflow needs a hole so it can purge air as its entering or leaving. itd be the same as blowing into a coke bottle. you cant blow in them unless theres a small hole. on modern cars the overflow is like a water tower. it sits higher and keeps coolant full by gravity.but those has a spin on plastic cap if those areoverfilled and ran it will blow coolant all over the car. think of those as not an overflow but a viewable top of the radiator.
 

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is not your fucking bro
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7,216 Posts
and im just talking in theory im not saying this is whats wrong with your bike. im just saying heres how the system works. what you should do is take it to a buddy with a radiator pressure tester and test the system for leaks. those things are cheap. then with the same tester use the adapter and check the cap.
 

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is not your fucking bro
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7,216 Posts
here the tester would go right on the radiator. or you can put the tester on the aluminum adapter and the cap on the other side of the adapter. the pump it and see if it will open at the rating
 

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Function IS Form
19 Z900, 88 Kat11
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17,433 Posts
I've worked on a few cooling systems with massive amounts of Stop Leak gunking them up... I've actually had to condemn an engine because someone plugged their cooling system with Bar's... and they only used the recommended amount... Bar's recommends based on a car cooling system, which is a lot higher capacity that a bike's...

I know that's probably not it but I figured I'd throw it out there.
 
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