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Cadillac & LaSalle Club Forums => Technical / Authenticity => Topic started by: Aniruddh on June 18, 2017, 07:07:56 AM

Title: Oil spurring out of the breather pipe, 1951 Cadillac
Post by: Aniruddh on June 18, 2017, 07:07:56 AM
Yesterday while backing my car from its usual parking found a fair amount oil on the ground. Upon inspection noticed that when the car is running a fair amount of oil being dropped thru  the engine breather pipe. This is when the car is on . When shut it's not leaking , this is the first time I have noticed it.

Can some one give me some advise as to what could have gone wrong ? Thank you

Attached some images
Title: Re: Oil spurring out of the breather pipe, 1951 Cadillac
Post by: The Tassie Devil(le) on June 18, 2017, 07:29:11 AM
Excess oil out the breather, or for the correct term, the Draft Tube, is the result of Piston Ring blow-by, where the piston rings can't completely seal the side of the cylinder.

This in turn pressurises the internals of the Sump and forces the oil-laden air out through the draft tube.

How old is the engine, as in the condition since it was last rebuilt, or the mileage.   It it high.   Does the engine consume oil?   Does the draft tube produce much smoke whilst the vehicle in under way?   This will require a second person in another vehicle, travelling in the same direction, and observing what comes out of your vehicle in the draft tube area.

Suddenly having a lot of oil appearing is not good, and time for things like Compression Checks, etc, and checking the condition of the oil filler cap.   It is blocked?   Perform both the dry and wet check when doing the Compression Check.

Bruce.  >:D
Title: Re: Oil spurring out of the breather pipe, 1951 Cadillac
Post by: Aniruddh on June 18, 2017, 08:06:40 AM
The car from its last rebuild must have not even done 200 km. I noted all what you have mentioned and will check it tomorrow. Thank you

Title: Re: Oil spurring out of the breather pipe, 1951 Cadillac
Post by: 35-709 on June 18, 2017, 08:04:57 PM
If that is happening with a fresh engine, something is definitely amiss.
Title: Re: Oil spurring out of the breather pipe, 1951 Cadillac
Post by: Steve Passmore on June 19, 2017, 01:55:18 AM
You need to be absolutely certain where it's coming from first. Your middle picture of the draft tube looks fairly clean inside to me and not conducive to the amount of oil on the floor.  As already stated, if it is from the tube on such a new engine there's deep trouble. Run the engine and check underneath to confirm the source.
Title: Re: Oil spurring out of the breather pipe, 1951 Cadillac
Post by: Aniruddh on June 19, 2017, 04:22:17 AM
Sirs, Thank you for all the details. Post yesterday I cleaned the area to 100% determine the leak if from any other external source . I check and recorded that its from the breather tube only.

Attached clip for viewing

Sadly !! A new engine

Title: Re: Oil spurring out of the breather pipe, 1951 Cadillac
Post by: The Tassie Devil(le) on June 19, 2017, 04:59:53 AM
Sorry, but cannot open it.

For oil to be "pouring" out the draft tube, there would have to be an excess amount of oil in the sump for the crankshaft to create such an internal vortex, plus an excess of Compression Ring leakage to pressurise the sump.

Plus, the Draft Tube is designed to only draw out excess fumes from the internal cavities as the vehicle is being driven, as it is designed to act as a simple Venturi, which removes the air from the tube by the forward motion of the vehicle creating a Vacuum at the rearward part of the tube as the outside air passes around the end of the tube.

Bruce. >:D
Title: Re: Oil spurring out of the breather pipe, 1951 Cadillac
Post by: Jay Friedman on June 19, 2017, 07:21:22 AM
Let's assume for a moment a best case scenario where nothing is wrong with the piston rings. 

In my '49 with the same 331 motor, I have had excess pressure in the crankcase (oil pan here or "sump" in Tasmania) caused by a combination of the downdraft tube being partially blocked and the breather cap (oil filler cap) being blocked with dirt.  On the other hand, in my case it caused a rear main bearing seal leak. 

Nonetheless, as a first step I would clean out thoroughly the breather cap in mineral spirits or other solvent.  Next, I suggest you remove the downdraft tube and check to see if it is clean internally as well as whether its upper end seats well in the place where it is goes into the valley cover.  It should sit "squarely" in the valley cover with a small cork gasket, and be held down securely by a long bolt.

If these don't improve things, then a compression check should be done to see if the piston rings are OK.  The rings could not be seated, or maybe they were installed wrong. 
Title: Re: Oil spurring out of the breather pipe, 1951 Cadillac
Post by: 35-709 on June 19, 2017, 03:27:16 PM
"The rings could not be seated, or maybe they were installed wrong."

With that low mileage it could be (hopefully) that it just needs some good hard running for further break-in.  If the engine has been started and stopped a lot to listen to how nice it sounds without a good run, it could well be possible that the cylinder walls have become glazed and the rings are not seating --- and unfortunately may not seat without pulling the heads and pistons and de-glazing the cylinder walls.  Worst thing you can do is baby it, don't abuse it but don't baby it either.
Title: Re: Oil spurring out of the breather pipe, 1951 Cadillac
Post by: tripwire on June 19, 2017, 08:49:54 PM
Is it possible the crankcase is overfilled?

Does the oil feel like new oil?  It looks very dark (to me) for oil that's only been in an engine for only 200 km. (125 miles).  Any possibility of gasoline getting into the crankcase, like when a car won't start due to getting "flooded" or running extremely rich, as in a choke that doesn't open fully? 

WParo in VT
Title: Re: Oil spurring out of the breather pipe, 1951 Cadillac
Post by: Jay Friedman on June 19, 2017, 09:27:16 PM
35-709,

Could the cylinder walls become glazed after only 200 km. and repeated starting and stopping as you wrote?  It may be that the cylinder walls were not honed during the rebuild or that the rings were not installed with the ring gaps 120 degrees apart from each other. 
Title: Re: Oil spurring out of the breather pipe, 1951 Cadillac
Post by: The Tassie Devil(le) on June 19, 2017, 09:51:45 PM
The cylinder walls can become glazed whilst it is sitting around, stopping and starting, and if the Cam cas not been run in correctly.

200 Km could have been done in very short increments, and at low speeds.   The Glazing will usually occur when an engine has been babied, and without any sort of strain.

The bedding in process will make any owner, who isn't used to the process, tear their hair out, and there is nothing worse for a owner to be there when the cam is run in.

Further, any sort of Friction Modified oil will assist in glazing of the bores, and rings, as the Friction Modified compound retards ring bedding in.

Bruce. >:D

PS.   Sorry Geoff for butting in.
Title: Re: Oil spurring out of the breather pipe, 1951 Cadillac
Post by: Jeepers Creepers on June 19, 2017, 11:42:28 PM
Do a leak down test..... you'll know if its the engine straight away.

Title: Re: Oil spurring out of the breather pipe, 1951 Cadillac
Post by: Jérôme506237DX on June 20, 2017, 05:24:42 AM
In addition to all mentioned above: does your engine have the correct dipstick?
Title: Re: Oil spurring out of the breather pipe, 1951 Cadillac
Post by: 35-709 on June 20, 2017, 06:33:40 AM
 "PS.   Sorry Geoff for butting in."

 ;D  Anytime, couldn'a  said it better.