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Oily Mist

March 07, 2015, 07:11:40 am

Observed issue
We recently made a trip from Georgetown, Tx to Pensacola.
When checking my oil level I discovered a more than usual oil film over the bottom frame, engine cover, and lower portions of the passenger side rear. According to the dip stick, the engine oil  level was fine.

There was a misted oil covering on the bottom center back and right again when I got home.
Dipstick still within hash marks.

I thought initially that it was oil from a slightly leaking fan seal but there was nothing on the hoses in the right side of the E.R.
Saw no leaks around the engine.

After a couple of days I noticed an oil patch under a hose (pipe?)  hanging vertically from the neighborhood of the lift pump area. The end of the pipe was significantly oily.

It appears that the oily mist is coming from underneath and being blown back from this pipe so I am willing to concede that it is the culprit.

Other Data
I had the valves adjusted (which required removal of the valve cover and a replacement gasket) and a resonator installed in Nac just before (in coach-mile time) the trip. I had not noticed anything unusual after returning to Georgetown.

Suggestions?  Diagnosis?  Warnings?

I will be at Mid-South in Breaux Bridge in a couple of weeks and will open the engine door for a guided tour.

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Re: Oily Mist

Reply #1 – March 07, 2015, 07:50:14 am

Hi, any oil on the tow? I occasionally had that issue from the blow-off tube you described as "verticle hose".

Oil level affected it. Seemed every time I topped off or changed oil, I got that condition.

Unfortunately for you, NOT EXPERT HERE, as you say observation and my experience.

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Re: Oily Mist

Reply #2 – March 07, 2015, 09:53:43 am

Very hard to guess from long distance. Could it be diesel instead of engine oil? Diesel does not evaporate much and with a little dust like a DP makes, could be the culprit. A little bit makes a big mess.

Pierce

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Re: Oily Mist

Reply #3 – March 07, 2015, 10:11:13 am

My guess is the oil was too full. My U225 would do the same thing until I learned to not fill the crank case all the way to the upper line on the dip stick. It was particularly noticeable when I was in a hurry and ran higher than normal speeds.

My U300 likes the oil level just barely above the lower line and will also blow out excess oil. WHIW

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Re: Oily Mist

Reply #4 – March 07, 2015, 10:27:25 am

Yup, need to know what kind of oil:

Could be engine oil (black)

Could be ATF (red/pink)

Could be hydraulic fluid (if engine oil is fluid, would be clear)

Diesel-- would smell like diesel

Coolant would smell like coolant

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Re: Oily Mist

Reply #5 – March 07, 2015, 10:32:15 am

I add a piece of plastic tubing to the blow by tube to extend it down a bit below the oil pan, helps keep things cleaner. Also keep the oil level down a bit off of full. Just a note if you add tubing to extend the tube don't put any bends in it or try to run it to the back or side of the coach, it must be unrestricted.

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Re: Oily Mist

Reply #6 – March 07, 2015, 04:40:31 pm

I was having a problem with excessive oil down the vent tube.  It was ending up getting blown around the inside of the engine compartment and back on the toad.  Extended the tube and added a plastic bottle to catch what came out.  Ended the mess.  After about 10K miles, the problem has almost gone away.  No idea why but my oil consumption is also way down.

Rich

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Re: Oily Mist

Reply #7 – March 07, 2015, 04:58:57 pm

Rich,
Appears your rings are about seated in the cylinders, some engines and uses require many miles to fully seat the rings, maybe 50,000 miles or little more.  There are safe ways of seating the rings earlier.

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Re: Oily Mist

Reply #8 – March 07, 2015, 05:26:49 pm

If this is blow-by, two suggestions:

Calibrate the engine oil dipstick.  It is free when doing an oil change.  Do NOT assume that the dip stick is accurate-- it is not supplied by the engine manufacturer.

Do NOT add oil until the oil reaches the "add" mark (yes, on a calibrated dip stick). 

And, as Bruce posted, extend the crankcase breather (aka slobber tube, aka vent tube...) lower and aft.  But, critically in cold climates, make sure it only goes downhill from the engine/no drip loop.

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Re: Oily Mist

Reply #9 – March 07, 2015, 10:49:13 pm

Thanks all!!

It is oil .
For the nonce I'll treat as if overfull condition.

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