Milky white in oil cap but not in dipstick

This could be something as simple as your:

PCV being stopped up.

PCV installed backwards.

Hose loose, kinked or sucking flat.

Goo stopping up hoses or piping in the PCV system.

If you take the PCV loose and crank up the engine, it should have some good suction at the PCV.

Be mindful of those evil moving parts!

The PCV sucks harmful blow-by combustion gases (water is a part of this) out of the crankcase and sends them back through the intake to get re-burned.

As it is sucking the crankcase's air out, fresh air is replenished into the engine through the air cleaner (o duct-work feeding from it.)

So, look at that too!

If the fresh air hose "in" is plugged off, kinked, or full of goo that would be the same as stopping up the system. If the PCV cannot suck the fresh air through the system it is just like the system having a blockage anywhere.

I see this same but simpler issue many times with 1960's, 1970's, 1980's Jeep CJs whereas the owner will install a second PCV on the back of the engines valve cover to "Make things look prettier" from the valve cover up to the air cleaner. Or because the original elbow is gone. The second PCV fits the hole perfectly! Wow! I am a genius!

The problem here is the second PVC now has reversed air flow and it "checks" (like a check valve). Fresh air is six inches away but cannot flow through the closed PCV. The bad stuff remains trapped in the engine.

Let us know what you find.

The Medic

I am guessing a "silencer" is what we call a "muffler" over here.

If so, it is damage would not cause the milky snot-like substance in the oil cap.

If you think your oil is tainted from excessive water in it, the dip stick might show the same stuff on the tip. Or even draining the oil and inspecting it might verify this problem being worse than I described in the first post.

However, if you do check out the possibilities in my first answer and find a deficiency in your PCVs ability to operate correctly and you fix it.

Clean your cap off and you should notice that it does not reappear!

Let us know how it goes.

The Medic

Good morning.

Just to add to CJ responses, a rich fuel mixture will cause the milky build up on your cap.

That could come from a dirty air filter, injector spray pattern off, or worn piston rings.

Change the oil, have the injectors cleaned professionally, not adding and additive as they have no effect, new air filter and have a wet and dry compression done.

Roy

You are welcome.

We are always glad to help.

Roy