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Discussion Starter · #1 ·
What can cause water to mix into oil?
‘08 f250 6.4 with 200k miles. It’s been Tuned and deleted. After fresh oil change and topped off coolant, Can drive for about 30 min before it needs more water.
With oil drain plug out, fill water and pressure test and the water comes out the oil pan drain.
That seems like a pretty bad leak, to me, internally somewhere. Can that tell you what’s more like to cause the water mixing into the oil?
 

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A common problem with the 6.4's is erosion of the front cover allowing coolant to leak thru to the engine base.
Another less likely suspect could be a ruptured oil cooler. However water would only leak to the oil side when the engine is stopped, Oil would actually enter the coolant side with the engine running due to the oils higher pressure. It would show up in the coolant expansion tank.
 

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Discussion Starter · #4 ·
Any advice for a DIY’er on changing the front cover on a 6.4l ?
I’m getting water in the oil, (no oil in the water). With oil drain plug out, topped off reservoir, did coolant pressure test and water came out the oil drain…
 

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Are you sure that the problem is the front cover? There are more common places for coolant to leak into the oil, such as the oil cooler o-rings (I'm not positive, but pretty sure the 6.4L has an oil cooler). It's a heck of a lot easier to change the oil cooler than the front cover, which likely entails pulling the engine, removing the oil pan, ....... etc.
 

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To inspect the front cover for erosion, remove the cooling water pump. The damage if it's there, will be directly behind the water pump. Be careful with the water pump the impeller is plastic.
 

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