Oil in antifreeze sbc

I am in need of some advice guys.It was a hot day sunday ,engine temp was running about 220 .started cutting out like not getting gas. Died wouldn't start,checked fuel filter no gas. figured vapor lock .Towed it home and went out a few hours later fired right up So I figured I would check the antifreeze level.Stuck my finger in radiator and found oil mixed in with it. Looked a little closer& found a small amount of oil/antifreeze mix on the intake manifold by 3 of the bolts.The bolts were about1/4 turn loose. So I went up and picked up a new set of intake bolts and thread sealer.Replaced the old bolts and found that the 2 bolts close to leak didn't seem to have any sealer on them.I drained the oil out of motor it is clear no signs of antifreeze in the oil . plan on flushing cooling system tonite ,fill it up with just water and see what happens.Does anyone have any ideas how oil got into my radiator. THANKS

 

I'd bet on a blown head gasket.

 

Is there a trans cooler in the rad? It could be leaking. ?.

 

so, what is over all condition of motor? Have you had overheating problems before? good seal at radiator cap? last time that you checked coolant? have an over flow tank? unusual to have vapor lock on SBC. what kind of fuel pump? post a pic of engine.

 

Thought about running a compression check ,no trans cooler to radiator

 

Check the oil fill cap for a white/brown slime. They also have a test kit you can use, it detects exhaust vapors escaping from the cylinders into the cooling system.

 

Stock 350 probably about 40,000 miles on it since rebuilt. I have about 600 on it ,picked it from a friend. noticed it running a little warmer in traffic last week .new griffin radiator and cap when I put it together .checked coolant about 2 days earlier ,no overflow tank.Will post a pic tonite when I get home.

 

lets just hope that its a head gasket .....

if its not well, ouch ....

 

likely a head gasket..

 

I've had a 305 and a 350 in 2 different GM pick ups and both had intake gaskets go.
Both were still under warranty - the 350 did it again at about 120,000 miles.
Radiators got all muddy...
I know 305's were notorious for intakes.

Before you go yanking heads off - check that out on your way....
I'm not sure if a compression test would show a head gasket gone or not.
Maybe a leak down test.

 

Oil in the radiator is WAY different than coolant in the oil. Head gasket leaks and intake leaks will put coolant in the oil, but hardly ever will it put oil in the coolant.
Keep in mind that the cooling system is pressurized at about 20psi. Oil cannot get into the coolant unless the oil is able to overcome the pressure of the cooling system. Very few places where pressurized oil comes into contact with a coolant passage.......usually in the lifter bore area......which unfortunately involves a cracked block.

 

Thats what I was thinking.^^^^ Cracked block is the only thing I can come up with.

 

^^^^ yep that is most generally it happens.
You don't always have water in oil when you have oil in water.

 

If there is an issue with the check valve in the radiator cap or the overflow tube is plugged, there will be a vacuum in the cooling system when the engine cools off, so drawing a little bit of oil in from a loose/leaky intake is not beyond the realm of possibility.

But then again, I'm an optimist....

 

My money is on a cracked block. Been there, and it sucks.

 

Check your plugs

 

so, just installed radiator? after install did you run car without radiator cap off or loose to allow air to release from system? do you have a working heater or use bypass hose from intake manifold to water pump? what is the rating of the pressure cap? did you flush out engine cooling system before installing new radiator? how long did you run motor after you saw it overheat?

 

If you have a tranny cooler in the radiator. That is a good possibility.

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My experience was a blown head gasket

 

Try this to determine if its a blown head gasket.
Remove the radiator cap and start the car.
You should see your coolant moving/flowing at a slow pace.
If your head gasket is blown, the coolant will look like boiling water.

 

Your original problem was that the car stopped running but it started after you towed it home.
Sounds like crap in your fuel line. What happens is something is pulled into the fuel line and plugs the fuel filter. After it sits for awhile the plug backs off allowing the car to start.
Was your car low on gas?

 

The radiator has been about yr ,15 lb cap, no heater or bypass hose.cooling system was flushed before adding new anti freeze last sept. I have been driving it since oct. & got about 600 mi. on it. no problems .probably ran it about 5 min after it hit 220,was a little over a mile from home when it died. compression test120-125 on all cylinders flushed system tonite will run it tomorrow and see what happens

 

No half a tank of gas .hot day I thought it vapor locked

 

fan have full shroud? I people think that they are ugly but, running a bypass hose from intake to water pump helps keep air bubbles from forming in system = cooler system.
hopefully you saved coolant in open container so, you could see how much oil is in coolant - not where animals can get to it.

 

No shroud yet but its on the next thing list.Never thought about bypass hose.coolant is in 5 gal can .

 

OK so I flushed the cooling system last nite refilled with water. I ran it for 30 min this morning temp held steady at 180.just checked the radiator ,here's what I found......Guess I will start pulling it apart today and see whats bad.....

 

Well I think you guys are right....pulled intake & heads today gaskets were in good shape.No visible signs of a crack anywhere.

 

no fun to deal with, time to pull motor.

 

Make sure you check that the heads have not warped