Ok so I just bought a 2000 jeep Cherokee sport last month and I've been checking the fluids regularly and today I noticed a milky substance in the radiator. The radiator over flow container appears to have oil in it as well. The oil for the motor seems to be fine and not milky at all as far as I can tell. When I start it and it warms up the oil press gauge stays above 40 but when I stop at a light or stop sign or sit in the parking lot and let it idle it drops to around 30. I'm wondering what could be wrong and if I should look at getting a new head or check other things first?

 

Because it's a 2000 and I assume the 0331 casting is still on it, don't drive it until you investigate further. There may still be hope of only replacing the head. Check engine compression and test the antifreeze to be sure what you're seeing is oil.

 

^ What he said ^ but do park it till you find the cause for sure.

 

Is it engine oil or transmission oil? Doesnt the tranny cooker run inside the radiator?

 

It looks like engine oil it's a light brown it looks like it's just starting to mix

 

 

good news?

this is the easiest engine to work on I've ever encountered... you, and your standard toolset +a good tq wrench can have a new head and gasket planted in five hours or less... and that is with beer and stogie breaks.

 

el oh el

 

by the way.... you may want to check that a/t fluid... it's hella more likely your rad is trying to kill your transmission than you have engine oil in your coolant...

the coolant is under greater pressure than the oil... it's pretty hard for them to cross... not hard at all for coolant to push into oil, though.

 

The head looks cracked between the #3 and #4 cylinder. Here are some pictures the last one with the discoloration on the cylinder is where I think it's leaking from hard to get a good picture tho

 

Yep. That's exactly where the 0331 likes to crack. Replace it with a Clearwater head.

 

Your rockers look pretty clean etc. that sure looks cracked. You should try the same camera angle when the engine is running and to temp and i bet youll see it bubbling out. Its kind of weird its making its way into the coolant and not other way around.

 

Um, no. It's typical for a blown head gasket or a cracked head to put oil in the coolant.

This is a 2000. The head is a known problem.


Rolling, once you have the head replaced, see my sig #4 to clean things out again.

 

there are at least 99 ways to go about this rather than being a smart ***, which marks you as a punk that hides behind a computer screen and avoids real men.

i just swapped the 0331 head on a 2000. mine was cracked between 3/4 too- on the mating surface, not between the rockers as his was.

further to my point, though- even cracked there (and if all the way through) the coolant is still at greater pressure than the oil- which means the coolant was pushed through the crack with combustion gasses to the oil and drained back into the sump. that is how coolant gets into oil. that's pretty much the only way unless the head gasket is blown. if the head gasket is blown or the head is cracked from a coolant port to the galley side of the gasket, there can be coolant aplenty in the crank case.

the only way for oil to get into the coolant is for a gravity assist through a crack or blown gasket after the engine is shut down. the coolant is at higher pressure and that advantage is compounded with an assist of combustion pressure giving the coolant a push. it's pretty much that simple. smart ***.

 

I love having that meme on stand-by for the 0331 head xj's.