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Coolant leak?

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wornsprokets
the 900
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Coolant leak?

Post by wornsprokets on Tue 29 Dec 2015, 3:55 pm

I went for ride today with cb with new bt45s.no problems. So i usually let cb run out of fuel with fuel tap off as i am not regularly using it at moment . So i was oiling the chain waitng for cb to cut out. And coolant starts flying out one of pipes under neath and hear expansion bottle bubbling.? I change rad and coolant in march and had no probs since(i was doing 600mile weeks at one stage? And no probs... whats caused leak and temp gauge was only middle way?
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teamster1975
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Re: Coolant leak?

Post by teamster1975 on Tue 29 Dec 2015, 5:19 pm

Did the fan come on? It will only belch out coolant from the expansion tank overflow if it has "boiled over" or the coolant is being pressurised.
I'd top up the coolant, check for air locks and make sure the rad fan is operating (usual suspect the earth wire snapped off top of rad).
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wornsprokets
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Re: Coolant leak?

Post by wornsprokets on Tue 29 Dec 2015, 5:25 pm

No i turned it  off gauge was half way when coolant came out and it was fair bit of it. Fan was working while ago.i check tomoro
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cbeebies
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Re: Coolant leak?

Post by cbeebies on Tue 29 Dec 2015, 5:30 pm

Could be a leaky head? Cylinder gasses pressurising the coolant jacket
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wornsprokets
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Re: Coolant leak?

Post by wornsprokets on Tue 29 Dec 2015, 5:48 pm

I hope not Sad
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wornsprokets
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Re: Coolant leak?

Post by wornsprokets on Tue 29 Dec 2015, 5:52 pm

I dont think so its head gasket. Engine oil fine, loads of power engine wise, the engine in general run very cool it never goes half way on gauge.

sullivj
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Re: Coolant leak?

Post by sullivj on Tue 29 Dec 2015, 6:59 pm

I've read that a faulty rad cap can cause this, but can't remember why.

A search would probably help.
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wornsprokets
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Re: Coolant leak?

Post by wornsprokets on Tue 29 Dec 2015, 7:57 pm

I think  somthing in cap can stick.i  get coolant tomoro and check everything(if it doesnt rain) dam no shed yet Rolling Eyes
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wornsprokets
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Re: Coolant leak?

Post by wornsprokets on Wed 30 Dec 2015, 2:15 pm

Wel i took bike apart today after coolant bubbling in expansion tank and coming out one of the pipes under neath bike yesterday, so tank off and took off radiator cap and radiator was full to neck with coolant?, checked cap and all hoses.every thing seemed fine ran bike for half hour or more .gauge didnt goe even half way . If coolant blows out again ive new coolant and rad flush. Very strange.
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eternally_troubled
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Re: Coolant leak?

Post by eternally_troubled on Thu 31 Dec 2015, 10:27 am

Very odd. If you can't get it to happen again after a few tries then just ignore it and imagine it hadn't ever happened Smile

More seriously - do check that fan switch/radiator earthing - it is the most likely thing to fail and will stop your fan working!
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wornsprokets
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Re: Coolant leak?

Post by wornsprokets on Thu 31 Dec 2015, 11:00 am

The fan was working during year and i copper greased the connection  on thermostat and connection to fan when i put new radiator on in march.  We see in next few weeks
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badseeds
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Re: Coolant leak?

Post by badseeds on Thu 31 Dec 2015, 4:00 pm

This happened to me when my radiator cap stopped pressurising the system. A new cap sorted it. They're generic across the model range, some Honda cars, too.
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wornsprokets
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Re: Coolant leak?

Post by wornsprokets on Thu 31 Dec 2015, 5:44 pm

Thanks for that bad seeds , will little donkey be back on road in 2016
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badseeds
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Re: Coolant leak?

Post by badseeds on Thu 31 Dec 2015, 5:50 pm

@wornsprokets wrote:will little donkey be back on road in 2016

Hopefully! My plans have kinda stalled at the moment.... We've been staying at the mother-in-laws whilst she's in India (til April) and the plan was to use her garage to fix up Little Donkey. However, my wifes aunt is currently 'between houses' and is staying here and the garage is full of her crap. She's supposed to be moving somewhere permanent, but it's not going to be ready til March :-( Or something.
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wornsprokets
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Re: Coolant leak?

Post by wornsprokets on Thu 31 Dec 2015, 5:58 pm

Are u enjoying the new black and pink cb, fuel economy got better.( i like the colour:))
 An other cb same as yours and same colour again went for 1300 euro. Old cbs are rare here now(dublin anyway)


Last edited by wornsprokets on Thu 31 Dec 2015, 6:14 pm; edited 1 time in total
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badseeds
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Re: Coolant leak?

Post by badseeds on Thu 31 Dec 2015, 6:04 pm

Fuel economy is actually slightly worse, but not worrying about; 185 miles to reserve instead of 200 on Donkey. New bike feels revvier, but Donkey has a sweeter gearbox and just feels smoother.
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wornsprokets
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Re: Coolant leak?

Post by wornsprokets on Sun 10 Jan 2016, 3:10 pm

Wel i got a second hand radiator cap and  thermostat for the cb hopefully it wil do the trick. If not i be looking for a new engine if head gasket is gone Sad
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eternally_troubled
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Re: Coolant leak?

Post by eternally_troubled on Sun 10 Jan 2016, 5:52 pm

@wornsprokets wrote:Wel i got a second hand radiator cap and  thermostat for the cb hopefully it wil do the trick. If not i be looking for a new engine if head gasket is gone :(

Assuming the radiator cap etc doesn't work - it might be worth investing in a compression gauge so you can compare one cylinder to the other - if both show good compression and they are pretty similar then it's probably not a compression leak that's causing the water get pressurised.
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magicman-alex
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Re: Coolant leak?

Post by magicman-alex on Mon 11 Jan 2016, 9:58 pm

Both Teamster1975 and I have struggled with this problem (and probably a few others on here!).

He had to replace his engine (head gasket). I replaced absolutely EVERYTHING apart from the engine, until I found out that it was a faulty water pump. (Intermittent fault so an absolute SWINE to diagnose).

If you're sitting on the bike and you look down at the left hand side of the radiator, there's a cable that runs into the radiator (attached to the thermal switch), just above the bottom coolant hose.

If you pull that cable off and touch the internal part (spade connector) to the outside ('nut') part of the fan's thermal switch, the fan should rotate. (You'll obviously need power to the bike at this point). If so, you know your fan is OK.

As you'll find mentioned plenty of times on here, it's a very common fault for the radiator earth at the top of the radiator to break. Check it hasn't broken because it will need to be re-made (not difficult).

Apparently it's very rare for a radiator cap to go. The Haynes manual will give you the specs for the temperatures at which the fan switch and thermostat itself should kick in.

sullivj
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Re: Coolant leak?

Post by sullivj on Mon 11 Jan 2016, 10:17 pm

Glad you got sorted Alex. Thanks for the tip about the fan.
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wornsprokets
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Re: Coolant leak?

Post by wornsprokets on Sun 17 Jan 2016, 2:13 pm

Well ive busy of late and havent been using cb, ive been on night shifts at moment any way so i got a second hand radiator cap and thermostat for €20 ,(took out plugs they were fine) so i checked coolant again and put a little into radiator and expansion bottle, so i went for long ride and no probs, came back ran cb on it centre stand for at least half hour, fan rad came on half way on guage at least four times and no expansion bottle coolant bubble up or coolant out one of pipes. Hopefully thats it(i didnt put second hand thermostat in) if its solved, thanks very much lads for advice and badseeds. I had a motor lined up if head gasket was gone. Guy wanted 300 euro but it had 18k but would u believe a breaker Evil or Very Mad

sullivj
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Re: Coolant leak?

Post by sullivj on Sun 17 Jan 2016, 5:32 pm

Glad that fixed it.

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