The Ford Barn

Chewie46 · 11-25-2022, 04:05 PM

there is some kind of a slot or vent on the front passenger side of the oil pan on my 40 Ford coupe. it that supposed to be there and is it some kind of a breather? Should oil be coming out of there?

alanwoodieman · 11-25-2022, 05:41 PM

part of the engine vent system

Mart · 11-25-2022, 06:54 PM

Yes it is a road draft tube. If oil is really flowing from there you have a problem. If just a little misty staining then it is probably normal.

There is a tube inside the valve chamber that connects to this breather passageway. If that is missing you might get a lot of oil going down there.

Mart.

V8COOPMAN · 11-25-2022, 10:02 PM

Quote:

Originally Posted by alanwoodieman

part of the engine vent system

Chewie.... As Alan says, it's part of the crankcase ventilation on'35 thru '48 engines. That front pan thingy is the point of crankcase air intake, as seen in the drawing BELOW.

As Mart said, there is SUPPOSED to be a tube in the front corner of the valve chamber (seen BELOW) which mounts above that vent orifice at the pan's surface. If this tube is not in place, or if it has been dislodged in some manner, circulated oil could seep directly down that hole, causing the symptoms you describe.

Coop

Brian · 11-25-2022, 10:55 PM

Actually coop, that illustration showing the breathing is backarseward!! it shows a pipe from the oil filler cap to the air cleaner. That is not original....originally, air enters the engine through the filler cap/breather, circulates through the engine and exits at that vent in bottom front of pan.

Newc · 11-25-2022, 11:03 PM

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I welded a flat plate with a pipe coupling in place of that vent and made it a pvc connection- worked well. Newc

V8COOPMAN · 11-26-2022, 05:17 AM

Quote:

Originally Posted by Brian

Actually coop, that illustration showing the breathing is backarseward!! it shows a pipe from the oil filler cap to the air cleaner. That is not original....originally, air enters the engine through the filler cap/breather, circulates through the engine and exits at that vent in bottom front of pan.

Brian.... I would be inclined to believe that too, as the routing shown in the drawing goes against anything I had ever read, especially when considering common sense and the "DRAFT" theory while the vehicle is in motion.

Coop

.

Mart · 11-26-2022, 05:36 AM

Yeah the addition of the tube from oil fill area to carb side of the filter reverses the flow.

V8 Bob · 11-26-2022, 08:15 AM

This is the correct ventilation for production 221"/239" '35-'48 flatheads. Sorry about the small size but I had no luck enlarging it. (:

Mart · 11-26-2022, 08:47 AM

...

Mart · 11-26-2022, 08:52 AM

8BA stylee:

outsider347 · 11-26-2022, 07:03 PM

Confused...which way is it?

My 40 / original engine shows blow by out the oil fill breather

Mart · 11-26-2022, 07:09 PM

Quote:

Originally Posted by outsider347

Confused...which way is it?

My 40 / original engine shows blow by out the oil fill breather

The road draft tube only works when the car is moving at speed down the road. Standing still you will see some blowby from the filler. It depends on how worn the motor is of course.

In the first picture shown you can see where someone has retouched all the arrows to point the other way. This is not the stock setup and is only confusing matters.

Mart.

Pete pa · 11-26-2022, 07:17 PM

Post #9 and #10 are correct. The bottom is the exit, top is entrance.

Seth Swoboda · 11-28-2022, 05:10 PM

I've gotten blow by smell from the oil filler cap on some older flatheads I've run. Not disputing the flow, just an interesting observation.

Ronnieroadster · 11-28-2022, 05:39 PM

When you see oil film on the oil pan vent and vapor plus fumes coming out of the breather on the oil fill tube its caused by the pressure that's going into the oil pan area of the engine. Those two areas are actually vents. That pressure needs to go someplace.
Ronnieroadster

cas3 · 11-28-2022, 07:29 PM

Sorta kinda related, my Willys M38 army jeep was made to be run submerged in water. The engineers figured there is about 2 lb's of pressure in the crankcase if you sealed it closed. They then used that pressure to blow air out, instead of water running in. Also ran that pressure to the trans and transfer case and distributor to keep water out. It has a manual valve at the PCV to close it and make pressure. Todays history class...over

11-25-2022, 05:41 PM	#2
alanwoodieman Senior Member Join Date: May 2010 Location: upstate SC Posts: 2,963	Re: 1940 Ford oil Pan part of the engine vent system

11-25-2022, 06:54 PM	#3
Mart Senior Member Join Date: May 2010 Location: Solihull, England. Posts: 8,754	Re: 1940 Ford oil Pan Yes it is a road draft tube. If oil is really flowing from there you have a problem. If just a little misty staining then it is probably normal. There is a tube inside the valve chamber that connects to this breather passageway. If that is missing you might get a lot of oil going down there. Mart.

11-25-2022, 10:55 PM	#5
Brian Senior Member Join Date: May 2010 Location: Masterton, New Zealand Posts: 3,834	Re: 1940 Ford oil Pan Actually coop, that illustration showing the breathing is backarseward!! it shows a pipe from the oil filler cap to the air cleaner. That is not original....originally, air enters the engine through the filler cap/breather, circulates through the engine and exits at that vent in bottom front of pan. __________________ Unfortunately, two half wits don't make a whole wit!

11-25-2022, 11:03 PM	#6
Newc Senior Member Join Date: May 2010 Posts: 2,484	Re: 1940 Ford oil Pan Sponsored Links (Register now to hide all advertisements) I welded a flat plate with a pipe coupling in place of that vent and made it a pvc connection- worked well. Newc

11-26-2022, 05:36 AM	#8
Mart Senior Member Join Date: May 2010 Location: Solihull, England. Posts: 8,754	Re: 1940 Ford oil Pan Yeah the addition of the tube from oil fill area to carb side of the filter reverses the flow.

11-25-2022, 04:05 PM	#1
Chewie46 Junior Member Join Date: Jun 2010 Location: Las Vegas NV Posts: 6	1940 Ford oil Pan there is some kind of a slot or vent on the front passenger side of the oil pan on my 40 Ford coupe. it that supposed to be there and is it some kind of a breather? Should oil be coming out of there?

11-26-2022, 08:47 AM	#10
Mart Senior Member Join Date: May 2010 Location: Solihull, England. Posts: 8,754	Re: 1940 Ford oil Pan ...

11-26-2022, 08:52 AM	#11
Mart Senior Member Join Date: May 2010 Location: Solihull, England. Posts: 8,754	Re: 1940 Ford oil Pan 8BA stylee:

11-26-2022, 07:03 PM	#12
outsider347 Member Join Date: Dec 2016 Location: Orchard Park NY Posts: 93	Re: 1940 Ford oil Pan Confused...which way is it? My 40 / original engine shows blow by out the oil fill breather

11-26-2022, 07:17 PM	#14
Pete pa Member Join Date: May 2010 Location: allison park pa Posts: 89	Re: 1940 Ford oil Pan Post #9 and #10 are correct. The bottom is the exit, top is entrance.

11-28-2022, 05:10 PM	#15
Seth Swoboda Senior Member Join Date: May 2010 Location: Southern Illinois Posts: 3,795	Re: 1940 Ford oil Pan I've gotten blow by smell from the oil filler cap on some older flatheads I've run. Not disputing the flow, just an interesting observation.

11-28-2022, 05:39 PM	#16
Ronnieroadster Senior Member Join Date: Dec 2010 Location: East Coast in CT Posts: 1,529	Re: 1940 Ford oil Pan When you see oil film on the oil pan vent and vapor plus fumes coming out of the breather on the oil fill tube its caused by the pressure that's going into the oil pan area of the engine. Those two areas are actually vents. That pressure needs to go someplace. Ronnieroadster __________________ I use the F word a lot no not that word these words Flathead , Focus and Finish. "Life Member of the Bonneville 200 MPH Club using a Ford Flathead block" Owner , Builder, Driver of the First Ford Flathead bodied roadster to run 200 MPH Record July 13, 2018 LTA timing association 200.921 in one and a half miles burning gasoline. First ever gas burning Ford flathead powered roadster to run 200 MPH at Bonneville Salt Flats setting the record August 7th 2021 at 205.744 MPH

11-28-2022, 07:29 PM	#17
cas3 Senior Member Join Date: Jan 2011 Location: sw minnesota Posts: 4,577	Re: 1940 Ford oil Pan Sorta kinda related, my Willys M38 army jeep was made to be run submerged in water. The engineers figured there is about 2 lb's of pressure in the crankcase if you sealed it closed. They then used that pressure to blow air out, instead of water running in. Also ran that pressure to the trans and transfer case and distributor to keep water out. It has a manual valve at the PCV to close it and make pressure. Todays history class...over