Appears to be oil in my radiator

[Sonny]

New 440 rebuild. Maybe 2 miles on the engine. Runs great. A small amount of oil (tan floating solution) settles on top of antifreeze under radiator cap after a few hours of sitting. I can soak most of it out with a paper towel or two.

What should my first step be to determine source?

 

[66 Sat]

Headgasket leaking?

 

[GTX JOHN]

Oil could get in Cooling system from any number
of places in engine. I would check for water in Oil
(Milkshake appearance). Also check trans dipstick for
water in ATF if Auto. Several times I have had radiator
cracking between engine and transmission cooling sections.
Perhaps it is just a residual and if all above looks good I would
run it for a longer period and inspect again.

 

[kiwigtx]

New 440 rebuild. Maybe 2 miles on the engine. Runs great. A small amount of oil (tan floating solution) settles on top of antifreeze under radiator cap after a few hours of sitting. I can soak most of it out with a paper towel or two.

What should my first step be to determine source?

If that tan liquid keeps appearing after every time to remove it.....you have a problem.

If its just a one-off occurrence, it could have been lube from installing a hose on the radiator, or somewhere else in the water line.

Take the advice above, and check the transmission fluid colour....and also look at your oil breather cap for signs of frothing white-ish residue.

 

[Sonny]

Oil could get in Cooling system from any number
of places in engine. I would check for water in Oil
(Milkshake appearance). Also check trans dipstick for
water in ATF if Auto. Several times I have had radiator
cracking between engine and transmission cooling sections.
Perhaps it is just a residual and if all above looks good I would
run it for a longer period and inspect again.

I run the trans fluid though a separate cooler not in the radiator. Thanks for responding!

 

[kiwigtx]

I run the trans fluid though a separate cooler not in the radiator. Thanks for responding!

It is unusual for the trans line to break inside the radiator bottom tank (but not impossible) - it is a lot heavier grade tubing than the trans cooler lines.

 

[zyzzyx]

You can look in the radiator while the engine is running and see if there are any
air bubbles, and you can do a pressure check on the cooling system while cold
and see if the coolant dissapears!

 

[Don Frelier]

It is unusual for the trans line to break inside the radiator bottom tank (but not impossible) - it is a lot heavier grade tubing than the trans cooler lines.

I did have that happen years ago. Pink milkshake for trans fluid. But it was a really old radiator that had run hot several times

 

[Lefty71]

I would drain, hot flush if possible and refill with water (its free). Maybe there's no issue?? I would make sure before tearing into a new build.

 

[dvw]

If there was oil in th eradiator, it would be full of green slime/goo. Skim it off with a paper towel. I wouldn't worry about it.
Doug