Coolant in oil?

RUSSLEE

MEMBER
1998 FORD F-150
5.4L
V8
2WD
AUTOMATIC
298,000 MILES

Truck stuttered and cut off; low fuel light was on thought I was out of gas. Put in some gas and started for the gas station. I had rough idle at a red light and temperature needle went up, so I pulled over and checked revivor, no coolant, approximately 12-14 bottles of water added still empty.
My neighbor who is a mechanic told me to drive the short distance home don't let it overheat, and immediately drain. I got about 6 gallons of chocolate milk out of the oil pan. Had a thought about head gasket so I poured a gallon of water into the coolant tank which came straight out the oil pan. Truck has an oil cooler with tow package and your site mentioned coolant getting pulled into oil even when not running.

5 Replies

BORIS K

MECHANIC
762 POSTS

Hello,

Your symptom points towards possible blown cylinder head gasket/gaskets.
A leaking oil cooler would push oil into the cooling system as the oil pressure is much higher than the cooling system pressure.

Coolant mixing with oil:
https://www.2carpros.com/articles/coolantantifreeze-in-the-engine-oil

As the water drains straight out of the oil pan when added to the coolant tank indicates a severe leak on either head gasket or a possible crack in a cylinder head casting. I have also seen severe corrosion on cylinder heads caused by a lack of antifreeze.

To investigate you will have to remove both cylinder heads.
Keep in mind that the engine is an overhead cam design which has dual timing chains. See image below.

A quick removal guide:
https://youtu.be/WexXN5VhFyU

Please let us know if you require detailed repair instructions

Cheers, Boris

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Friday, January 6th, 2023 AT 4:22 AM

RUSSLEE

MEMBER
4 POSTS

How does water get up to the cylinder head without the engine running? The reservoir feeds into the lower radiator hose right beside the oil cooler lines. And the gallon I poured in came out of the oil pan 5-10 seconds later.

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Friday, January 6th, 2023 AT 5:04 AM

BORIS K

MECHANIC
762 POSTS

Hello,

Does the oil cooler on your engine look like the image below?

If so then you can remove the 2 water pipes, fitted to the 2 stubs above the oil filter.
Bridge them out with a piece of tubing or simply block them off.
Fill water again, if water still runs out of oil pan, then it cannot be from the oil cooler.
As mentioned previously, a leaking oil cooler will push oil into the cooling system as the oil pressure is far higher than the coolant pressure.

Cheers, Boris

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Friday, January 6th, 2023 AT 9:11 AM

RUSSLEE

MEMBER
4 POSTS

Thanks, I was wondering how to test. I have no fluid in the coolant reservoir and no radiator cap. I guess I’ll need to open the peacock to see if I have oil in the radiator.

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Friday, January 6th, 2023 AT 9:21 AM

RUSSLEE

MEMBER
4 POSTS

With oil cooler lines off and plugged. Water poured into coolant tank came out of oil pan after 5-10 seconds. 298,000 miles time to get a crate motor. Thanks for your help!