antifreeze leak Help antifreeze in oil

Brandie Smith · September 14, 2020

I have a 1996 GMC Sierra k1500, I recently I had to replace the clutch system, after that the truck started to go through antifreeze like crazy we could never figure out where it was going (no leaks that were visual) truck never over heated. we ended up replacing the hoses, we went ahead and put in a new alternator thinking the fan was not working. after that, the truck started to overheat so we put in a new radiator, went to do an oil change seen that the oil was milky, so drained everything did full oil change including filter, checked oil again and still has a watery milky color in the oil. Can anyone please tell me what to do from here? TIA

****MORE DETAILS: Great thank you will try the plug thing I have had truck setting since Sat. here's something that got me thinking, when replacing the radiator, we noticed that the oil cooler lines on the old radiator had a o ring to them, the new radiator did not, so he used the old o ring when attaching to the new radiator. could this be causing a bleed over ?

Edited September 16, 2020 by Brandie Smith
more detail

riverbanks · September 14, 2020

Take out the spark plugs ,one at a time,look for a very clean one,or crusty gunk on it,this way you can isolate which cylinder is the culprit, the problem could be,intake gasket,head gasket or cracked head

Doug_Scott · September 14, 2020

I think it is too late for the obvious, but, back away from the wallet. It is a very rare day that throwing money at something will fix it. Antifreeze can enter the crankcase only a couple of ways. The first and second most common ways are in the cylinder head area. The head could be cracked, or could be porous. Check out this thread

. Your truck is a little bit early to have the bad heads, but, its still something that is usually the first thing checked. A blown head gasket could also let coolant into the crankcase. What you need to do is this, loosen the radiator cap and let the truck idle in the driveway. Get it hot, but do not drive it. Once it is hot, tighten the cap up. Let truck idle 5 more minutes, then shut it off. Let the truck sit for a couple of days, the longer the better. After a few days, put a clean drain pan under the oil pan. Loosen the drain plug slowly, and watch to see what comes out of the drain plug first. If you see fluid the same colour as your anti-freeze then you now know for sure it is something to do with heads.

By running the engine with the rad cap loose, it will prevent the coolant from getting into the crankcase. After tightening the cap and running it for 5 minutes or so, it will build some pressure up. Shutting it off will also push the pressure up a bit, and if there is a pressure leak in the cylinder heads, it will push coolant into the crankcase. Since oil is lighter than coolant, and then engine is not running, the coolant will gather in the bottom of the pan. Over time some oil will give up the coolant, and it will sink to the bottom of the pan. Anything that leaks in without engine running will go straight to the bottom.

You could also just let the truck sit a few days without running it at all, and loosen the drain plug on the stone cold engine and watch what comes out first. You should be able to slowly loosen the plug and use the plugs slow down the first of the liquid to drain out. The oil is cold and will not flow very fast making it easier to keep the plug at the last thread. Water will be easy to see coming out, but, don't blink or turn your head away. Let us know what comes out when you try this.

KARNUT · September 15, 2020

You could always use a block sealer to buy some time while you’re deciding what to do. I’ve used it on head gasket problems on old stuff. Know people who’s had cracked blocks to seal water leaks. Sometimes that all that was done. Worth a shot to buy time.

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Brandie Smith · September 15, 2020

Great thank you will try the plug thing I have had truck setting since Sat. here's something that got me thinking, when replacing the radiator, we noticed that the oil cooler lines on the old radiator had a o ring to them, the new radiator did not, so he used the old o ring when attaching to the new radiator. could this be causing a bleed over?

Doug_Scott · September 18, 2020

On 9/15/2020 at 12:46 AM, Brandie Smith said:

Great thank you will try the plug thing I have had truck setting since Sat. here's something that got me thinking, when replacing the radiator, we noticed that the oil cooler lines on the old radiator had a o ring to them, the new radiator did not, so he used the old o ring when attaching to the new radiator. could this be causing a bleed over?

No, the o rings are there to prevent the line from leaking outward. Those lines are also transmission cooler lines.