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Discussion Starter · #1 ·
have a cbr 600 f3 that has developed a problem with the coolant level in the rad dropping.

recently had the rad fully removed to get at some seized exhaust studs.
i stripped the rad and exhaust myself and had a mechanic extract the studs. i then refitted the rad and topped up coolant, burped the rad and topped up the expansion tank.

been keeping an eye on coolant level after rides and noticed its low each time i check it but it seems to only drop to the same level each time on short or long rides.

so today i started looking into it and have noticed that the level is dropping slowly even without starting the bike, but seems to be only when the bike is warm, but again only to the same level as when running.

if i fill it up to the rad filler neck and let it sit for around 30min with the cap off and bike not running, the level slowly drops to around 30mm below the filler neck, which is level with the bottom of the pipe to the thermostat, but the pipes not completly emptying. i have refilled it several times and cant figuire out where the coolant is going, no overflowing from any pipes etc.

i couldnt get all the exhaust studs out myself so i took it to a mechanic to pull the 3 seized ones.
i think he welded nuts and washers on them all and now im thinking could he have put too much heat into it with the welding?? i would have thaught this would send oil and fuel into the coolant but there seems to be no sign of any cross contamination.
has anyone ever had any problems with coolant leaks after welding exhaust studs?

so far iv only visually checked some things, all hoses for leaks, oil not milky, water pump and seal hole not leaking, no oil in coolant, also opened up the manifolds and checked its not leaking into the exhausts.

is there some dumbass thing im missing or doing wrong or is it likely the welding of the studs could have caused a wharp or crack in the head?
any help or advice on what to do next will be appreciated.
 

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Discussion Starter · #2 ·
here is a pic of the rad filled, and then after sitting for around half hour not running
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b
20210714_182144.jpg
20210714_182144.jpg

20210714_190605.jpg
 
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