Yellow foam inside oil filler tube
 

Gentlemen,

A question for you.....

The 31 has a stock motor that runs absolutely wonderful. Smooth and powerful despite many miles on it. Have been using 10w-40 synthetic oil in it. A few days ago I checked the oil and saw it was just a little low so decided to add some. Upon removing the oil cap, I noticed a bright yellow "foam" inside the filler tube and on the bottom of the cap. It wouldn't come off with alcohol but it was very creamy and came off easily with a screwdriver. I ended up using a cleaner designed for removing flux from circuit boards to clean it out of the tube.

Looked inside engine and all looks normal. Oil on dipstick looks normal. Coolant level was only down very slightly which is normal. Car runs nice and cool. Asked two guys and no ideas. How about you guys? Any ideas?

Re: Yellow foam inside oil filler tube
 

I run a thermostat in the winter for just this issue. I see California but cool outside temps and a motor running less than 140 can cause this.

Re: Yellow foam inside oil filler tube
 

yes usually a t-stat prevents this as tin cup mentioned.... for shits and giggles i would also crack loose the drain plug just to make sure no h2o is in there.....

Re: Yellow foam inside oil filler tube
 

Until just a couple of weeks ago I was driving my PU to work every day. It has a 160 thermostat, but in the 4 miles or so each way, it doesn't have a chance to stay up to temprature more than 5 or 10 minutes. Thus the foam.

To keep that from happening, a 30 minute or so run once a week warms it up and stays up enough to dry out all the condensate and eliminate the foam.

Re: Yellow foam inside oil filler tube
 

Tin- I don't have a thermostat in the car, partly because the old- "Henry didn't put it there so it isn't needed." I put a piece of cardboard over the radiator with a folded top and hole cut to clear the motometer for the first warm-up each day before driving. I let the car warm up until the motometer hits about 140 (it's calibrated and marked), then take the cardboard off and go about the day. See pic below.

Mitch- VERY good advice, thanks! Nothin but oil (whew!). That was a relief.

Carl- That's a good tip. Usually when driving the car, it's a trip to town and back and a few errands along the way. It's 5 miles each way plus whatever errands.

The major panic here was the color of the foam- Bright yellow with an almost orangeish hue. Never seen that before. It was pretty thick, but not viscosity wise. Viscously speaking, it was almost (but not quite) creamy enough to fall off with gravity. The thing is, it took some pretty nasty cleaner to clean it out of the filler tube. Simple isopropyl alcohol wouldn't touch the stuff.

Re: Yellow foam inside oil filler tube
 

Oh, another question-

When the filler tube was out and I could see into the crankcase, it looked really super clean in there. I could see the oil puddle in the dipper trays for #1 and #2. When cranking the motor and looking through the hole, I did not see the oil puddles touched by the crank as it came around. Isn't the crank supposed to go into those puddles of oil as it rotates? Is the dipper tray too low?

Re: Yellow foam inside oil filler tube
 

Idling the car to warm it up isn't doing it any favours. Starting it up, get it running just right, and drive off - gently.While idling, a lot of combustion gases are being pushed past the rings, into the cold crankcase, where the moisture condenses into adic (think acid rain!). Driving gets it up to temp faster, and once the crankcase is warmed up, there's less condensation, and eventually the moisture evaporates (though the acidic deposits are still in there).

Most modern cars require more regular servicing if you do a lot of city driving and idling (Severe Service), because of this type of thing.

Also, Idling doesn't get all the other parts of the car up to operating temp either - the gearbox and diff will still be almost dead cold (certainly the diff!).

Either fit a thermostat, do longer trips every now and then, or change the oil more often and clean out the crud.

At least you have the right oil in there!

Re: Yellow foam inside oil filler tube
 

P.S,
I drove Minerva about 500 miles a month with an in hose 160 degree thermostat & NEVER saw anything funny in the cap or tube. 140 degrees is way too cold to get rid of condensation. Cooler is not always better, with a thermostat, your mileage will even get better & except for a few really cold days, I NEVER even had to open my GAV!
Bill W.

Re: Yellow foam inside oil filler tube
 

I put in temp gauge , and the gauge never moved it stayed at less then 100deg I drove about 10 miles at high speed. way to cold. I put in a thermostat in the upper hose and water temp is to 160 right away