Leaking head gasket?

[Brian]

Hey folks!

During the winter months, I don’t do much with cars since I don’t have a garage any more. Since my background is in autobody that specialized in salvage rebuilds and restomods, I inspect cars that people want to buy.

I’ve found services like carfax to be unreliable since they only show body damage that was reported, not what was done under the table on the cheap before the car was dumped on the next person.

While my experience is mainly autobody, I’m also pretty good under the hood. It’s not my speciality, but I’ve learned plenty over the years.

The reason for this posting, is that I’m starting to wonder if I’m misdiagnosing blown head gaskets on cars that my customers want to buy.

I know that if there is white sludge on the dipstick, that’s pretty obvious. I’ve been seeing it a lot under the oil fill cap too. Mostly, I find white milky slime under the oil fill cap but not on the dipstick. That leads me to believe that the car lots change the oil to make it look clean just long enough to get it sold.

I’ve also been told that residual moisture can collect under the oil fill cap and make just the one pocket of milky slime.

I know that heads can crack and head gaskets can crack in different directions causing different kinds of leaks in different directions, like compression leaking into the coolant, or oil in the water, or water into the oil.

I took a drive in a very low miles park ave recently that a customer REALLY was jonesing for. Low miles, no odd noises and a velvety smooth ride. We pulled into a gas station on the test drive. I was almost unable to remove the dipstick or the oil fill cap. They came loose, then I saw the clear layer of super glue used to keep them in place. You should have seen all that milky slime in that smooth sounding engine!

In my area, this seems a fairly common. Even the big name dealerships are pushing out late model cars with “clean” carfaxes that have blown head gaskets are have clearly been redone poorly after being totalled.

Would any of you say that having milky slime only under the oil fill cap is a clear sign of a leaking head gasket, or would you say its a sign of a leaky head gasket that they are covering for with a recent oil change?

Topic

[Jon Hart]

As you know the milky residue is moisture build up this can occur for several reasons one being a blown head gasket, other being lots of very short journeys where the car does not reach a hot enough temp to “burn” the condensation as cars at dealerships are always being moved about worked on a car that has been sitting at the dealerships for some time may well have a milky residue that was not caused by a head gasket issue, it can also be caused by the dealerships jet washing the engines to make them cleaner which makes the technicians cringe every time they see it.

[Richard Kirshy]

” Would any of you say that having milky slime only under the oil fill cap is a clear sign of a leaking head gasket, or would you say its a sign of a leaky head gasket that they are covering for with a recent oil change? ”
I have a 2002 Nissan with 85,700 on the clock and for the past several years, only put ~600 miles a year on it now.
Last spring while servicing it, I noticed the dreaded “pudding” on my oil fill cap.
Worried I had a bad head gasket, I did all the tests for it, Compression, pressurized radiator even leak down.
After some research and discussions, I found out that with the limited mileage, this is a normal occurrence.
In an attempt to reduce the build up, I installed a oil catch can on to the PCV system late in the spring.
Since then,there has been no build up under the oil fill cap, but quite a bit of it has been caught in the catch can.

So when you say … “Would any of you say that having milky slime only under the oil fill cap is a clear sign of a leaking head gasket.”
I think you need to dig a bit deeper to identify the issue.
Never judge the book by the cover.

As to …”or would you say its a sign of a leaky head gasket that they are covering for with a recent oil change?”
Not saying there aren’t dishonest people in the world…
I’ve seen where people put saw dust or banana peels in rear differentials to quite them down.. Don’t ask about transmissions :S
But then again there is the possibility a head gasket leak got pass a mechanic and it was given a oil change.
I would hate to think that all dealerships and mechanics were that poor in business practices.

[EricTheCarGuy]

Residue under the cap does not necessarily mean the head gasket is bad. It’s actually normal for cars that ‘short trip’. Meaning they never get warm enough to burn off the condensation inside the engine that happens naturally.

I cover head gasket diagnosis here. I think it’s important to note that although head gaskets are the most frequent cause of a combustion leak into the cooling system, but it could also be a cracked head, cracked block, or leaking intake gasket that can cause similar symptoms.

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