The Ford Barn

Lincoln29 · 07-09-2022, 05:53 PM

I made a rear main drain tube for my 36 LB motor and it goes in the oil. But not sure this is the way to go. The Green Ford book doesn't show one for a 35 or 36. Any suggestions would be greatly appreciated.
Thanks, Jerry

Brian · 07-09-2022, 07:25 PM

My suggestion is that you've done the right thing. My thinking is this; the engines pre 35, [when crankcase ventilation was incorporated into the design], could experience a build up of crankcase pressure, which obviously tries to vent anywhere possible. As there is no positive rear crankshaft seal in these early engines, merely the labyrinth setup, this provided an escape route for this excess pressure. In blowing out through this area, the blowby can take oil with it, which then can contaminate the clutch area. By fitting an oil return line, the other end of which is submerged in the engines oil, the tendency is for this oil to return to the oilpan, not the clutch area.
Ok, so, with the introduction of positive crankcase ventilation in 1935, this escape route for crankcase pressurisation was eliminated, consequently, Ford did away with the long drainpipe. You, however, I notice, are running an 8BA style oil pump....this straight away is capable of feeding that rear main more oil than the original LB oil pump would provide. Your fitting a long drain pipe will be a great aid in returning this excess oil to the pan, not out the back of the engine. Don't worry, your Ford will still mark it's parking spot!! lol

Ken/Alabama · 07-09-2022, 07:52 PM

Always keep the rear main journal on the tight side of the specs.

Lincoln29 · 07-10-2022, 06:18 AM

Thanks guys, your advice is greatly appreciated. Looks like I should leave it the way I have it. Any other thoughts are always welcome. I plan on putting it back in the car next week.

Jerry Hollenbaugh

alanwoodieman · 07-10-2022, 06:41 AM

I have a little concern of it being too long, the original drain tube was half the lenght of your tube

Terry,OH · 07-10-2022, 09:54 AM

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All of the originals stop short of going into the oil. The later 81A pipes are only about 2" long OAL. Try to find a photo of an original.

rotorwrench · 07-10-2022, 10:37 AM

If the oil sump pan has the vent on the front right corner then the tube really doesn't need to be below the oil level in the sump. Ford started venting the crankcase around early to mid 1935. The air scoop they put on top of the engine oil filler tube was problematic after ring wear allowed excess blow by to get in the cabin so it was eventually deleted for the simpler oil filler cap.

Lincoln29 · 07-10-2022, 09:17 PM

Based on what you guys have told me, it won't hurt to leave it on the way I have it. You all have been very helpful to me.
Thanks,
Jerry

07-09-2022, 07:25 PM	#2
Brian Senior Member Join Date: May 2010 Location: Masterton, New Zealand Posts: 3,835	Re: 1936 LB rear main drain tube My suggestion is that you've done the right thing. My thinking is this; the engines pre 35, [when crankcase ventilation was incorporated into the design], could experience a build up of crankcase pressure, which obviously tries to vent anywhere possible. As there is no positive rear crankshaft seal in these early engines, merely the labyrinth setup, this provided an escape route for this excess pressure. In blowing out through this area, the blowby can take oil with it, which then can contaminate the clutch area. By fitting an oil return line, the other end of which is submerged in the engines oil, the tendency is for this oil to return to the oilpan, not the clutch area. Ok, so, with the introduction of positive crankcase ventilation in 1935, this escape route for crankcase pressurisation was eliminated, consequently, Ford did away with the long drainpipe. You, however, I notice, are running an 8BA style oil pump....this straight away is capable of feeding that rear main more oil than the original LB oil pump would provide. Your fitting a long drain pipe will be a great aid in returning this excess oil to the pan, not out the back of the engine. Don't worry, your Ford will still mark it's parking spot!! lol __________________ Unfortunately, two half wits don't make a whole wit!

07-09-2022, 07:52 PM	#3
Ken/Alabama Senior Member Join Date: May 2010 Location: Alabama Posts: 3,261	Re: 1936 LB rear main drain tube Always keep the rear main journal on the tight side of the specs.

07-10-2022, 06:18 AM	#4
Lincoln29 Senior Member Join Date: Aug 2010 Location: Plymouth, Indiana Posts: 111	Re: 1936 LB rear main drain tube Thanks guys, your advice is greatly appreciated. Looks like I should leave it the way I have it. Any other thoughts are always welcome. I plan on putting it back in the car next week. Jerry Hollenbaugh

07-10-2022, 06:41 AM	#5
alanwoodieman Senior Member Join Date: May 2010 Location: upstate SC Posts: 2,965	Re: 1936 LB rear main drain tube I have a little concern of it being too long, the original drain tube was half the lenght of your tube

07-10-2022, 09:54 AM	#6
Terry,OH Senior Member Join Date: May 2010 Posts: 4,751	Re: 1936 LB rear main drain tube Sponsored Links (Register now to hide all advertisements) All of the originals stop short of going into the oil. The later 81A pipes are only about 2" long OAL. Try to find a photo of an original.

07-10-2022, 10:37 AM	#7
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,440	Re: 1936 LB rear main drain tube If the oil sump pan has the vent on the front right corner then the tube really doesn't need to be below the oil level in the sump. Ford started venting the crankcase around early to mid 1935. The air scoop they put on top of the engine oil filler tube was problematic after ring wear allowed excess blow by to get in the cabin so it was eventually deleted for the simpler oil filler cap.