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gregk

Help needed: Milky oil in Crankcase

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Hi, Anybody able to advise on diagnosis. I have purchased a 2002 Gas Gas TXT PRO and done full service on the bike. Replaced water pump seal as engine oil was milky reamy colour. Bike starts easily but within few minutes(as soon as warmed up) coolant pushes out radiator overflow and new replaced oil turns milky colour. Have replace Fan(bearings shot) as well as new thermostat.

Flushed complete water system. No oil present in coolant when drained.

Any assistance would be appreciated.

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If its the one in the water pump you referring to I already replaced it due to the milky colour. Even after this change, first start and water in the new oil.

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thks for reply, any idea as to why the shaft normally also gets replaced. If I replace shaft should I do impeller as well?

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Shaft can wear where the seal runs on it,the impeller will be fine.As Lineaway says,replace the cylinder head 0 rings,cooling system is pressurised from combustion chamber leaking it

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A common problem with older models . Water pump seal / shaft very likely worn.  Shaft material poor quality. You should be able to see the wear point on the shaft & feel it with your fingernail.

***Just replacing seal won't fix it.***  You can buy a complete water pump overhaul kit .. Also worth checking out  cooling fan / T'stat  working OK while you have system drained, as this can be another problem child. 

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Thanks all for advise, did see shaft was a bit pitted, sanded down but probably still could be an issue. Will do a replacement kit which includes shaft. When ordering the cylinder head o-rings, is that the name they go by?

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Shafts are not "poor quality" they run at crankshaft speed so both should be replaced at the same time as the seal.

RULE: if you replace seal do the shaft at the same time.

And do not fill radiator right up to the top. There is no "expansion tanks" in this cooling system so leave 8-10mm air gap in the top header tank to allow for that "expansion" as it warms up and it will be fine. Top it all the way up and that few mls will just either blow out the pressure relief valve, or past that worn shaft in your case (which is easier - but it will go out of one or the other)!

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Hi , some people use die in cooling system , like food coloring die to find the leek use with clean water  ,, if other ideas don’t work , it’s cheep , 

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