4Runners Experiencing Foam under Oil Cap

[Thorn]

I came across a post on a Toyota 4Runner forum, and people are finding a frothy foam under their oil caps. I believe I remember reading here that Dodge/Jeep 4.7L V8s also have this problem, and it is partially due to an extended oil filler neck causing condensation.

My T4R V6 has a fairly long neck on the oil filler tube. I am not sure about the V8s. Does anyone here have any input?

Is this condition something to be worried about?

The attached link is to the T4R forum. I am including it because someone there has posted a picture of his frothy oil cap, although it doesn't seem like a whole lot of foam. Others have said that they noticed much more.

Any input is appreciated.

T4R Forum

[ January 17, 2006, 02:48 PM: Message edited by: Thorn ]

 

[Ray H]

Not a problem - just a harmless "characteristic" of extended oil-fill necks, especially with insulative plastic filler caps and operation in cool climates - especially with urban crawl driving. Ugly perhaps, but this is NOT sludge in the making.

 

[JohnnyLock]

In northern climates you would especially see this in garaged vehicles that are not run up to temp. If it's not on your dipstick or in your oil when you drain it no sweat. It's not something you'd want to see on a filler cap but I wouldn't worry about it. I have the 4.0 V6 down here in Texas in an 05 Tundra and have not experienced this phenomena.

 

[JohnBrowning]

It is fairly common on any engine dureing cold weather. Many modern engine designs have this hapen year round though to varying degree's. The vechiles that seem to be the most affected are ones with long fill necks that rise above the valve cover and are made out of aluminum,magnesium or some form of plastic.

I think it is a combination of hoter head temps,differing rates of cooling of materials, the long neck being the highest point on the engine and the more common use of oil airrators in heads.

I had a 2001 Dodge Dakota Quad Cab 4x4 SLT+ and it had this same foam issue. If you took the valve cover off the engine was clean and did not have any of the foam any place other then the oil fill area. Their was never any sign of coolant or water in my oil. My Mother's Tundra has a dime-nickle sized spot of foam under here cap dureing winter. My wife's buick has about the same amount as my mother's tundra but sometimes my wifes cap has only water droplets. Many Mercedes also experince this.

In the case of my Dodge I found that it was only a problem when the wife was useing it for mostly around town driveing. When I was driveing it too and from work witch was a 40 miles HWY drive I had no foam. I also found that synthetic oil cut the foam down by about 90% even with the wife driveing it.

I think that it is only representitive of a problem if water or coolant is found in the oil by UOA.

P.S. The reliance of highly volitile 5W30 dino oil in the USA proably does not help. I would suspect that the foam is water vapor and light volitile hydrocarbons seeking the highest point on the engine.