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Honda CX500 A 1980 UK bike - pods, no H box and ignitech ignition
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Discussion Starter · #1 ·
Hey guys, I have a mysterious leak of some rusty looking liquid down the right hand side of the engine along the front crank case gasket - see pic - any thoughts on what the cause of this could be? Cheers! Andy
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Oil or old coolant?

By the way your clutch cable is not installed correctly. The two nuts should both be above the perch. The one bearing on the perch adjusts for clutch free play, the nut directly above it serves to lock the nuts in position. If you don't already have a copy of the factory service manual visit the wiki, link in my signature, and download the one for your bike.
 

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Is it a constant leak while the motor is running? Does it only leak while warming up then stop leaking? Does it only leak when shut off and warmed up?
 

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Honda CX500 A 1980 UK bike - pods, no H box and ignitech ignition
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Discussion Starter · #5 ·
Oil or old coolant?

By the way your clutch cable is not installed correctly. The two nuts should both be above the perch. The one bearing on the perch adjusts for clutch free play, the nut directly above it serves to lock the nuts in position. If you don't already have a copy of the factory service manual visit the wiki, link in my signature, and download the one for your bike.
Many thanks regarding the clutch cable :)

It looks to be rusty coolant rather than oil…
 

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Honda CX500 A 1980 UK bike - pods, no H box and ignitech ignition
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Discussion Starter · #6 ·
Is it a constant leak while the motor is running? Does it only leak while warming up then stop leaking? Does it only leak when shut off and warmed up?
seems to be constant - it doesnt stop once Warmed up.
 

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You just need to look as Nolimitz has suggested. Hoses and o rings that can fail. You most definitely need to flush your cooling system if that's really the source of the leak.
 

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Could be something really simple like the tube that runs from the radiator neck to coolant expansion tank...thats thinner rubber than your main hoses....if its coolant
 

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Could be something really simple like the tube that runs from the radiator neck to coolant expansion tank...thats thinner rubber than your main hoses....if its coolant
I was thinking the same thing except it is a consistent leak while the engine is running. The leak is most likely from somewhere that is under pressure.
 

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Point taken.....OP was given guidance bout what to check......but I was thinking eliminating the obvious/simple first.... Radiator cap? The bottoms of when if not cleaned can be somewhat rusty.
Or maybe even those small water jacket nuts on the front of the head..(Dont overtighten those tho....)
 

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My guess is oil from the color. With a dearth of iron in these engines/coolant systems I wouldn't expect much rust staining. Isn't there a cam seal up there behind the fan? BTW, blueing on header indicates hot/lean engine burn, or aftermarket single wall construction, but maybe historical rather than now.
 

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If you are getting liquid drips rather than just staining, get some on your finger and feel or taste it, should clarify what it is. Do I have to state "Don't swallow it?" :rolleyes:
 

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If my coolant was that colour a leak would be the least of my worries....
That is a fairly common place for an oil leak but the marks look a lot more like rusty water to me. Are you sure it only happens when the engine is running?
But it is hard to tell from a picture. Feel it and let us know if it feels like oil, like water or somewhere in between (I wouldn't taste it).
The next step is to get on your knees with a flashlight and look for the same stuff higher up. You could also clean the area thoroughly and powder it (talcum, flour, any fine powder will do) then go for a short ride and look for tracks in the powder that you can follow back to the source.
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