The Ford Barn

joeyg · 05-07-2023, 01:44 PM

Hello, I dropped the pan on my 31 to investigate a major oil leak rear main, I purchased the car last year and do not know the history. I'm new to the model A world so please be patient with my lack of knowledge. I've been reading alot of threads on this site about rear main seal sealing techniques. Can someone please help me as I cant find any information on what I have and what type of solution is needed to go forward. It looks to me the crankshaft has been machined and one of the slingers have been removed. Also I removed a two piece rubber type seal from the block and the cap. Please see attachments... UGH..

Thanks Joe

Gene F · 05-07-2023, 01:55 PM

When the pan cme down, is there a little drain tube coming out of the rear main bearing cap. Like maybe 1 1/2 or 2" long?

nkaminar · 05-07-2023, 04:35 PM

The rubber seals wear out. Replace it. Look at Chevy V8 seals to see if they fit. Your Ace automotive part supply store may be able to help. Use a little silicone sealant at the joints.

Make sure there is not any restriction in the breather/filler pipe or cap so that the pressure in the crankcase does not build up. Try running the oil at the half way mark or less. The journal where the seal rides should be polished.

Make sure the lip on the seal faces towards the front of the engine. Use a little silicone sealant where the seal mounts to the block and bearing cap. Just a little sealant.

joeyg · 05-07-2023, 06:37 PM

Quote:

Originally Posted by Gene F

When the pan cme down, is there a little drain tube coming out of the rear main bearing cap. Like maybe 1 1/2 or 2" long?

Yes the tube is there, however the rubber seal shown actually covers the hole in the cap...

joeyg · 05-07-2023, 06:43 PM

Quote:

Originally Posted by nkaminar

The rubber seals wear out. Replace it. Look at Chevy V8 seals to see if they fit. Your Ace automotive part supply store may be able to help. Use a little silicone sealant at the joints.

Make sure there is not any restriction in the breather/filler pipe or cap so that the pressure in the crankcase does not build up. Try running the oil at the half way mark or less. The journal where the seal rides should be polished.

Make sure the lip on the seal faces towards the front of the engine. Use a little silicone sealant where the seal mounts to the block and bearing cap. Just a little sealant.

Thanks but easier said than done, Chicago area most parts suppliers around here have young kids that don't know a damn thing about engines, if its not in the computer they are no help.

jack backer · 05-08-2023, 04:56 AM

Sponsored Links (Register now to hide all advertisements)

If the bearing clearance is excessive oil will flow through the bearing faster than it can drain back into the block, this results in oil leaking out the back of the bearing.The root cause of your leak might not be the seal.

nkaminar · 05-08-2023, 05:51 AM

See if this fits: https://www.speedwaymotors.com/Speed...eal,34261.html

Charlie Stephens · 05-08-2023, 09:52 AM

Also check to see that there is a gasket between the block and the flywheel housing since you don't know the history.

Charlie Stephens

Ed in Maine · 05-08-2023, 11:23 AM

Joeyg, you mentioned that the rubber seal is covering the hole in the rear cap! That tube is the drain for oil that is supposed to go back into the pan. I used to have a Model A that someone lightly crimped this tube and then dropped a ball bearing into it for a partial seal. I had all kinds of spill over oil at the rear main especially when the oil was cold. Make sure the tube is open. Also, if the crank shaft has too much end play from a worn rear main cap thrust surface, the crank shaft will move back and forth slightly and pump oil out the rear main. Replace this rubber seal, make sure gaskets are installed in the correct places and the main cap oil return tube is open. Then hope for the best.
Ed

joeyg · 05-14-2023, 04:19 PM

Hello everyone, thank you for your replies. I have more information.
Please look at the main bearing cap and notice how someone machined the cap for the two piece seal. Also notice how the crankshaft has been machined.. Need help to determine what are your thoughts.
Thanks, Joe

johnneilson · 05-14-2023, 04:47 PM

joe,

I have no idea what seal that is, for some reason it reminds me of a BUDA diesel or mid 60's car.
That said, even if the seal was known from records on the car, it may not be found.
Rear main caps and crankshafts can be found used, just have to look around.
But, the first to determine is the condition of the crank, it looks to me like the thrust flange was partially removed. It may make the crank undesirable.
IMHO, Terry Burtz makes a seal kit for the "A" and "B" motors so I would look at the installation instructions first to determine if the crank is serviceable.

https://www.snydersantiqueauto.com/c...ain%20Seal.pdf

J

MAG · 05-14-2023, 04:59 PM

We had the same problem with the modern seal modification. In less than 5K miles on a new rebuild it leaked very bad. You don't want to know how it was fixed.

Kurt in NJ · 05-15-2023, 06:25 PM

The upper and lower Babbitt have to be touching tightly from the oil well to the thrust or there is a direct pathway from the oil supply to the seal area, too much oil passing the bearing can overcome any seal.
Your thrust looks to have chunk out of it at parting line, the edges at the cap look uneven , take some better pictures of the areas, and the block, put the cap on the block and look for gaps.

Originally I thought I needed a rubber seal,never used it ,was digging through old parts collection and found it, then dropped it onto the floor and it shattered like glass —— glad I didn’t use it.
The original rebuild leaked some and had a early failure (3000miles) the rear main crumbled and I decided to try doing it myself, I trimmed Babbitt flushto block before peining ,then after penning the parting line was raised a little putting where the Babbitt in the cap and block in compression like a insert so the fit was tight and no leak path at parting lines—- it worked for me,the car doesn’t drip on other peoples driveways, only drips a drop in the dark of night in its own garage.
I used a light cost of hylomar on the shims between them and the cap from oil pan seal groove to the rear, close attention to every detail of every possible oil path.

05-07-2023, 01:55 PM	#2
Gene F Senior Member Join Date: Mar 2012 Location: Ohio Posts: 1,973	Re: Major rear main oil leak When the pan cme down, is there a little drain tube coming out of the rear main bearing cap. Like maybe 1 1/2 or 2" long?

05-07-2023, 04:35 PM	#3
nkaminar Senior Member Join Date: Jan 2012 Location: Western North Carolina Posts: 3,897	Re: Major rear main oil leak The rubber seals wear out. Replace it. Look at Chevy V8 seals to see if they fit. Your Ace automotive part supply store may be able to help. Use a little silicone sealant at the joints. Make sure there is not any restriction in the breather/filler pipe or cap so that the pressure in the crankcase does not build up. Try running the oil at the half way mark or less. The journal where the seal rides should be polished. Make sure the lip on the seal faces towards the front of the engine. Use a little silicone sealant where the seal mounts to the block and bearing cap. Just a little sealant. __________________ A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past.

05-08-2023, 04:56 AM	#6
jack backer BANNED Join Date: Mar 2022 Location: Chenango Bridge NY Posts: 433	Re: Major rear main oil leak Sponsored Links (Register now to hide all advertisements) If the bearing clearance is excessive oil will flow through the bearing faster than it can drain back into the block, this results in oil leaking out the back of the bearing.The root cause of your leak might not be the seal.

05-08-2023, 05:51 AM	#7
nkaminar Senior Member Join Date: Jan 2012 Location: Western North Carolina Posts: 3,897	Re: Major rear main oil leak See if this fits: https://www.speedwaymotors.com/Speed...eal,34261.html __________________ A is for apple, green as the sky. Step on the gas, for tomorrow I die. Forget the brakes, they really don't work. The clutch always sticks, and starts with a jerk. My car grows red hair, and flies through the air. Driving's a blast, a blast from the past.

05-08-2023, 09:52 AM	#8
Charlie Stephens Senior Member Join Date: May 2010 Location: Southern California Posts: 7,033	Re: Major rear main oil leak Also check to see that there is a gasket between the block and the flywheel housing since you don't know the history. Charlie Stephens

05-08-2023, 11:23 AM	#9
Ed in Maine Senior Member Join Date: May 2010 Location: Washington Cty., ME or Flagler Cty., FL Posts: 1,106	Re: Major rear main oil leak Joeyg, you mentioned that the rubber seal is covering the hole in the rear cap! That tube is the drain for oil that is supposed to go back into the pan. I used to have a Model A that someone lightly crimped this tube and then dropped a ball bearing into it for a partial seal. I had all kinds of spill over oil at the rear main especially when the oil was cold. Make sure the tube is open. Also, if the crank shaft has too much end play from a worn rear main cap thrust surface, the crank shaft will move back and forth slightly and pump oil out the rear main. Replace this rubber seal, make sure gaskets are installed in the correct places and the main cap oil return tube is open. Then hope for the best. Ed

05-14-2023, 04:47 PM	#11
johnneilson Senior Member Join Date: Jun 2010 Location: 34.22 N 118.36 W Posts: 1,057	Re: Major rear main oil leak joe, I have no idea what seal that is, for some reason it reminds me of a BUDA diesel or mid 60's car. That said, even if the seal was known from records on the car, it may not be found. Rear main caps and crankshafts can be found used, just have to look around. But, the first to determine is the condition of the crank, it looks to me like the thrust flange was partially removed. It may make the crank undesirable. IMHO, Terry Burtz makes a seal kit for the "A" and "B" motors so I would look at the installation instructions first to determine if the crank is serviceable. https://www.snydersantiqueauto.com/c...ain%20Seal.pdf J __________________ As Carroll Smith wrote; All Failures are Human in Origin.

05-14-2023, 04:59 PM	#12
MAG Senior Member Join Date: May 2010 Location: Austin, Texas Posts: 925	Re: Major rear main oil leak We had the same problem with the modern seal modification. In less than 5K miles on a new rebuild it leaked very bad. You don't want to know how it was fixed. __________________ I noticed the harder I work the luckier I get!

05-15-2023, 06:25 PM	#13
Kurt in NJ Senior Member Join Date: May 2010 Location: on the Littlefield Posts: 6,159	Re: Major rear main oil leak The upper and lower Babbitt have to be touching tightly from the oil well to the thrust or there is a direct pathway from the oil supply to the seal area, too much oil passing the bearing can overcome any seal. Your thrust looks to have chunk out of it at parting line, the edges at the cap look uneven , take some better pictures of the areas, and the block, put the cap on the block and look for gaps. Originally I thought I needed a rubber seal,never used it ,was digging through old parts collection and found it, then dropped it onto the floor and it shattered like glass —— glad I didn’t use it. The original rebuild leaked some and had a early failure (3000miles) the rear main crumbled and I decided to try doing it myself, I trimmed Babbitt flushto block before peining ,then after penning the parting line was raised a little putting where the Babbitt in the cap and block in compression like a insert so the fit was tight and no leak path at parting lines—- it worked for me,the car doesn’t drip on other peoples driveways, only drips a drop in the dark of night in its own garage. I used a light cost of hylomar on the shims between them and the cap from oil pan seal groove to the rear, close attention to every detail of every possible oil path.