1940 Ford oil Pan

C

Chewie46

Junior Member
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?
 
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.
 
alanwoodieman said:
part of the engine vent system
Click to expand...


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.


391586


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


imageuploadedbyh-a-m-b-1392790033-088702-jpg.2140619
 
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.
 
I welded a flat plate with a pipe coupling in place of that vent and made it a pvc connection- worked well. Newc
 
Brian said:
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.
Click to expand...


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

.
 
Yeah the addition of the tube from oil fill area to carb side of the filter reverses the flow.
 
This is the correct ventilation for production 221"/239" '35-'48 flatheads. Sorry about the small size but I had no luck enlarging it. (:
 

Attachments

  • '35-'48 flathead ventilation.jpg #2.jpg
    '35-'48 flathead ventilation.jpg #2.jpg
    12.6 KB · Views: 53
Last edited:
outsider347 said:
Confused...which way is it?

My 40 / original engine shows blow by out the oil fill breather
Click to expand...

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.
 
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.
 
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
 
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
 
You must log in or register to reply here.
Back
Top