Oil in coolant

[bentwrench]

I'm working on a 1999 Expedition with a 4.6 engine. There is about 1/4 inch layer of oil on top of the coolant in the surge tank.
Can someone tell me where this most commonly comes from?
Thank you!

 

[5.0Flareside]

blown head gasket typically.

 

[SuperCab]

Head gasket or intake gasket would be my first guess... Does the oil look milky at all?

 

[bentwrench]

No the oil doesn't appear milky. It's quite dark, 1 qt low and needs to be changed tho!
The coolant in the jug that's under the layer of chocolate brown oil is nice and green.

 

[5.0Flareside]

No the oil doesn't appear milky. It's quite dark, 1 qt low and needs to be changed tho!
The coolant in the jug that's under the layer of chocolate brown oil is nice and green.

A blown intake gasket won't mix oil into coolant.


Ya got a blown head gasket. Oil sits on top of coolant and water.

 

[SuperCab]

Oops... Chris is right. You can get coolant in your oil with an intake leak, not the other way around.

I second him on the head gasket theory then.

 

[blacksnapon]

Oops... Chris is right. You can get coolant in your oil with an intake leak, not the other way around.

I second him on the head gasket theory then.

External leaking oil cooler. You got a filter inside the lf fender?

 

[5.0Flareside]

External leaking oil cooler. You got a filter inside the lf fender?

Very true! Forgot bout that!!

 

[bentwrench]

Not sure what u mean by a filter inside the LF fender...
I see only one set of cooler lines going to the radiator. I would suppose they are for the transmission.

 

[O'Rattlecan]

Some of these trucks have oil coolers mounted on the bottom/driver/front side of the engine block. Do you have an oil cooler mounted between the filter & block?

Ryan

 

[bentwrench]

I was just looking at alldata. Did not realize that the cooler is mounted by the oil filter.
Haven't looked yet to see if it has one there. I will check it out.
Thanks for the info!

 

[WTHLunatic]

go for new head gaskets clean the heads really well and inspects for cracks in the heads especially in the ports where the oil and antifreeze travel close to each other. Normally head gaskets will do this but if the engine has ever overheated it can cause the heads to warp and or crack allowing the anitfreeze to mix with oil or vise versa.

 

[bentwrench]

Nope. No oil cooler. Lookin' more like a head gasket all the time!

 

[bentwrench]

It turns out the owner of this vehicle had the engine rebuilt at an indie shop 15000 miles ago. The shop agreed to repair it for the owner for free! So I'm outta the loop thank goodness!

Thank you all for your replies. I sincerely appreciate it!

If you have any General Motors questions, feel free to ask me. I've been a tech at a Chevy/Buick dealership for 32 years.

Thanks again!

 

[bentwrench]

Owner of this vehicle traded it off. It's outa my hair!
Thanks for your responses!