The Ford Barn

ALJ · 06-19-2022, 05:33 PM

My 1931 Model A Coupe. Transmission oil is leaking into the differential. I know that because the oil level in the transmission goes down and the level in the differential goes up. I’m using 600 W oil purchased from the parts suppliers. I don’t know if the rear transmission bearing seal is in place. I have driven the car several hundred miles since purchasing it and have just discovered this condition. My question is, is this a problem that warrants pulling the transmission to check the seal? I will appreciate your comments. Thank you.

Bob C · 06-19-2022, 06:37 PM

The transmission has baffles at the input and output bearings but no seals. There
is a seal in the front of the torque tube that should stop out from getting to
the differential.

Kurt in NJ · 06-19-2022, 06:56 PM

have you checked to see if the vent hole in the shifter tower is open

GRutter · 06-19-2022, 07:09 PM

Original bearings were not sealed. New bearings are sealed. It is typical to pull the seal on the transmission side.
There is also an oil slinger on the rear bearing.
Check to make sure that the vent in the transmission tower is open.
Check that the oil level in the transmission is no higher than the filler plug - the rear main transmission shaft is well above the oil level.
Check that the differential housing is FULL of grease.

daveymc29 · 06-19-2022, 08:07 PM

Grease? Mine is filled with 600W and has been since I bought the car in the 90's, works fine for me.

GRutter · 06-19-2022, 09:46 PM

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Quote:

Originally Posted by GRutter

Original bearings were not sealed. New bearings are sealed. It is typical to pull the seal on the transmission side.
There is also an oil slinger on the rear bearing.
Check to make sure that the vent in the transmission tower is open.
Check that the oil level in the transmission is no higher than the filler plug - the rear main transmission shaft is well above the oil level.
Check that the differential housing is FULL of grease.

Sometimes I amaze myself by what I meant to say.
Corrected to "Universal Joint Housing"

Jim Brierley · 06-20-2022, 11:30 AM

Quote:

Originally Posted by Bob C

The transmission has baffles at the input and output bearings but no seals. There
is a seal in the front of the torque tube that should stop out from getting to
the differential.

This is correct. My pickup is lowered front and rear, so the torque tube slants down at its front. I had the reverse problem, oil was transferring from the diff into the trans. I reversed that seal so it now keeps the oil in the diff. Works great!

gdmn852 · 06-20-2022, 11:42 AM

Hello, does not seem to be that uncommon, just drain the rear to filler plug , and replenish the transmission, unless is excessive. Buick also have the problem, made worse with a Dynaflow, as ATF and gear lube don’t mix , usually a spring differential lube change is common.

ALJ · 06-20-2022, 10:13 PM

I wasn't aware of a vent hole in the shifter tower. Where is it located?

GRutter · 06-21-2022, 08:55 PM

Tower Vent Location. Be sure this is open to prevent any pressure buildup.

ALJ · 06-21-2022, 11:00 PM

Thank you. I will get the carpet and boot out of the way and check that.

06-19-2022, 05:33 PM	#1
ALJ Member Join Date: Feb 2015 Location: Manti, Utah Posts: 38	Transmission Oil going to Differential My 1931 Model A Coupe. Transmission oil is leaking into the differential. I know that because the oil level in the transmission goes down and the level in the differential goes up. I’m using 600 W oil purchased from the parts suppliers. I don’t know if the rear transmission bearing seal is in place. I have driven the car several hundred miles since purchasing it and have just discovered this condition. My question is, is this a problem that warrants pulling the transmission to check the seal? I will appreciate your comments. Thank you.

06-19-2022, 06:37 PM	#2
Bob C Senior Member Join Date: May 2010 Location: So Cal Posts: 8,754	Re: Transmission Oil going to Differential The transmission has baffles at the input and output bearings but no seals. There is a seal in the front of the torque tube that should stop out from getting to the differential.

06-19-2022, 06:56 PM	#3
Kurt in NJ Senior Member Join Date: May 2010 Location: on the Littlefield Posts: 6,159	Re: Transmission Oil going to Differential have you checked to see if the vent hole in the shifter tower is open

06-19-2022, 07:09 PM	#4
GRutter Senior Member Join Date: Sep 2017 Location: Mint Hill, North Carolina Posts: 386	Re: Transmission Oil going to Differential Original bearings were not sealed. New bearings are sealed. It is typical to pull the seal on the transmission side. There is also an oil slinger on the rear bearing. Check to make sure that the vent in the transmission tower is open. Check that the oil level in the transmission is no higher than the filler plug - the rear main transmission shaft is well above the oil level. Check that the differential housing is FULL of grease.

06-19-2022, 08:07 PM	#5
daveymc29 Senior Member Join Date: Sep 2010 Location: Danville, CA Posts: 1,554	Re: Transmission Oil going to Differential Grease? Mine is filled with 600W and has been since I bought the car in the 90's, works fine for me.

06-20-2022, 11:42 AM	#8
gdmn852 Senior Member Join Date: Feb 2019 Location: Erie Pa Posts: 689	Re: Transmission Oil going to Differential Hello, does not seem to be that uncommon, just drain the rear to filler plug , and replenish the transmission, unless is excessive. Buick also have the problem, made worse with a Dynaflow, as ATF and gear lube don’t mix , usually a spring differential lube change is common.

06-20-2022, 10:13 PM	#9
ALJ Member Join Date: Feb 2015 Location: Manti, Utah Posts: 38	Re: Transmission Oil going to Differential I wasn't aware of a vent hole in the shifter tower. Where is it located?

06-21-2022, 11:00 PM	#11
ALJ Member Join Date: Feb 2015 Location: Manti, Utah Posts: 38	Re: Transmission Oil going to Differential Thank you. I will get the carpet and boot out of the way and check that.