CBR 600F3 1995 - 1998 CBR 600F3 Forum

Sludge in my radiator

Old 12-11-2018, 08:22 PM
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Default Sludge in my radiator

My F3 has this brown sludge in the radiator, Iím figuring oil. Checked oil, clear as a bell but radiator is sludge. Drained it twice but still doing it, it also overheats and spits this sludgy liquid out of top hose on radiator, the tiny one going in to to cap part. Head gasket??? Anyone?
Old 12-11-2018, 10:27 PM
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Oil cooler seals are common, if yours is equipped with one. Couple of orings....
Old 12-11-2018, 10:30 PM
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If your oil is clean and you aren't losing coolant, it's probably just a bunch of crud built up over the years. Just keep flushing it with water until it comes clean.
I seem to remember a thread from a year or so ago where someone had the same issue. Take a look to see if you can find that thread.
Old 12-19-2018, 08:54 PM
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Originally Posted by 74demon View Post
Oil cooler seals are common, if yours is equipped with one. Couple of orings....
If your oil is clean and your getting oil in the cooling system (overflow tank or radiator), it's not a head gasket.
It is very common on F2/F3's when the oil cooler seals start to leak. This lets oil into the coolant.
They are easy and cheap to replace with the engine in the bike.

I've seen way to many people pull engine to do head gaskets when that isn't the problem.
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