white foamy milk on oil cap?

[ncsdaonex]

I bought a wrecked truck and im not sure if the engine is ok. The raadiator has a hole in it. The oil cap has white foam on it like u see when oil and water mix. Also I added antifreeze and when it leaked out the radiator it was a bright whitish green so idk if the oil cap was just condensation and if the radiator was a similar thing but I drained the oil after seeing this and it was clean only oil no mixture so i put the oil back in the engine so if the oil is clean does that mean everything is probably good?

 

[85_Ranger4x4]

Keep an eye on it, most engines will snot up the cap if they don't get ran enough to purge the block of condensation though.

 

[Mark_88]

Ah, the white foam has spread to other Rangers...must be a fungus among us...

There has been a few threads on this but I don't think it has been determined exactly what causes it...

Have you ran the engine or is it non-functional?

It's not a coolant leak in most cases...it is a product of "air whipping the oil into a foam"...and the air is usually the result of blow-by or excessive air pressure in the lower part of the engine...

The blow-by can be caused by leaky rings or valves or the foam may be due to a plugged PCV...that's the little valve at the top end of the engine that allows the air to be drawn up into the throttle body or carb...check that the PCV is working and/or replace it...if that doesn't solve it you may have to take the vent system apart and clean it up...and that isn't difficult but involves a bit of work.

 

[ap3x]

I see this on all makes and models of vehicles at work. Normally appears to be related to a leaking gasket of some sorts (valve cover, oil pan, etc.)

 

[ncsdaonex]

okay cool so engines prolly ok cause it has 174,000 on it and doesnt tap or anything and yes trucks been sitting awhile, i start it like once a week and drive it around the farm but itll be sitting awhile cause im swapping frames and converting from auto to manual tranny and some front end repair work.

 

[Muscleford]

I had my wife take our Thunderbird to the dealer for an oil change when I was traveling for business and did not have the time to do it myself as I usually do. They also tested the radiator but their tester did read correctly because I did not ethylene glycol antifreeze in the car. The freeze reading led them to believe I had been adding water because it read low. They told her we likely had a bad gasket. I had her take it in for diagnosis and they found NOTHING, only lightened my wallet. I have found that the white on the oil fill cap is normal especially if the majority of your driving is short hop. Just change you oil more often to reduce the acid that the moisture causes.

 

[97ranger xlt]

if the oil does not get to a sufficient temperature to burn off moisture you get the white coating on the oil cap. nothing to worry about. just get it on a long highway run and it should disappear.

 

[adsm08]

It's also usually worse in the winter months.

 

[Mark_88]

It's also usually worse in the winter months.

Yes, this is true...mine started doing it late last year and I thought "oh, great...here we go again"...

But it could be condensation in the oil from the heat of the engine cooling over night...another "a ha" moment...

I had thought it might be detergents in the oil or cheap oil...which I had been using...and I usually change the oil in December and again in March or April depending on how many miles I put on it...

 

[GoodOld85BlueBalls]

Every car I have ever had that sits too long has this same problem. It always makes me worry when I see it..

Does anybody know that if running synthetic could help with this?

 

[85_Ranger4x4]

Every car I have ever had that sits too long has this same problem. It always makes me worry when I see it..

Does anybody know that if running synthetic could help with this?

It doesn't really have anything to do with the oil.

If you notice a partially dranken (not sure if that is really a word? ) pop bottle forms water above the pop line. It comes from the moisture the air already in the bottle when you put a warm bottle in the fridge... same thing happens when your warm engine block cools down at night.