Differential fill plug torque
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Intermediate
Joined: Nov 2014
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Differential fill plug torque
Hello guys,
after having refilled the differential of my ´74 Corvette (454 Manual) there is frequently an oil drop on the bottom of the housing. Does anybody know the recommended torque for the fill plug and a wrench that fits best to its head? As far as I know there is no seal on the plug. Is that correct?
kind regards & thanks
Fritz
after having refilled the differential of my ´74 Corvette (454 Manual) there is frequently an oil drop on the bottom of the housing. Does anybody know the recommended torque for the fill plug and a wrench that fits best to its head? As far as I know there is no seal on the plug. Is that correct?
kind regards & thanks
Fritz
Race Director
Joined: Sep 2001
Posts: 10,560
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From: Wellington, FL
St. Jude Donor '11 thru '25
The plug is pipe threaded which requires no sealant. A 3/8 socket wrench is used to remove/install it. I've never torqued it but just snugged it in pretty good and never had a leakage problem. Be sure the threading is clean. BTW, are you sure it's the plug that's leaking?
Last edited by Jud Chapin; Mar 7, 2015 at 03:12 PM.
Melting Slicks
Joined: Sep 2004
Posts: 3,223
Likes: 666
From: Northeast
In my 78 Chassis manual as well as the Haynes Manual they call for 20 ft/lbs. To remove the plug I used a 5/8 8pt socket on a swivel and it worked fine.
I did not torque mine, just snug and no drips. No seal.
I did not torque mine, just snug and no drips. No seal.
Le Mans Master
Joined: Oct 2007
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From: Tennessee/Rhode Island
Team Owner
Joined: Jan 2006
Posts: 37,637
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From: Crossville TN
There is no pipe plug at the "bottom of the differential" in a stock GM unit. The stock plug is a 'fill' plug, rather than a drain plug, and it is on the side of the case. When setting fluid level, fluid is put into the case until it just begins to drip out of the 'fill' plug. Then, the plug is inserted and tightened to 20 ft-lbs. It would be unusual for the pipe-threaded fill plug to leak gear lube; but if it did, the threads could be cleaned and then get a wipe of Permatex #2 gasket sealer, then re-tightened.
If someone machined and installed a straight-threaded plug at the bottom of the case, it would certainly require sealant to keep it from leaking.
If someone machined and installed a straight-threaded plug at the bottom of the case, it would certainly require sealant to keep it from leaking.
