12 bolt diff cover leaking - The 1947 - Present Chevrolet & GMC Truck Message Board Network

crm318 · 11-10-2008, 01:47 PM

The other day i noticed that my differential cover on my 12 bolt rear was leaking. I had changed the fluid in it not too long ago and i heard here on the forums that most guys dont use a gasket and just use silicone (which i did). I took the cover off, cleaned the surfaces, applied a bead of silicone and new fluid. Today when i came out to my truck, it was leaking again. How thick is the bead of silicone suppesed to be? How long should i let it cure before i reinstall it? What do yall think?

cdowns · 11-10-2008, 02:55 PM

leaking rear covers is mostly due to overtightening of the bolts //they requirs 45INCH pounds of torque more causes the holes in the cover to dimple out causing leaks//i still believe in the original style gasket with a light coating of permatex avaition sealer

Elephanthead · 11-10-2008, 03:03 PM

Use "the right stuff", it is appropriately named gasket in a can. It keeps what you want in and what you don't want in out.

crm318 · 11-10-2008, 08:21 PM

I have a torque wrench i can use. Does that mean that its 3.75 foot pounds?

cdowns · 11-10-2008, 08:26 PM

sorry i dont know the proper way to convert inch pounds to ftpounds//i've got different torque wrenches for bboth

70c10 · 11-10-2008, 08:30 PM

Quote:

Originally Posted by crm318

I have a torque wrench i can use. Does that mean that its 3.75 foot pounds?

Yes

**leddzepp** · 11-10-2008, 08:39 PM

Very informative...I am having the exact same problem with my 12 bolt rear...I am SURE I have overtightened the bolts. I guess it is just like valve covers.

msgross · 11-10-2008, 08:46 PM

I take the stock gaskets and put a thin coat of RTV on both sides...and spread it out with my fingers... wouldn't hurt to let it cure for a bit then refill it and go driving...

zeeklu · 11-10-2008, 08:50 PM

When you clean the surfaces to be sealed ,I use brake clean or something similar so there's no oil residue. I also let the silicone dry over night or a couple of hours before adding oil. Chris

crm318 · 11-10-2008, 10:32 PM

Yea, i think i tightened the hell out of them (well more than 3.75 foot pounds). ill inspect the surfaces and do it correctly tomorrow. Thanks guys.

11-10-2008, 01:47 PM	#1
crm318 Alright Alright Alright Join Date: Mar 2004 Location: Midland, Texas Posts: 1,672	12 bolt diff cover leaking The other day i noticed that my differential cover on my 12 bolt rear was leaking. I had changed the fluid in it not too long ago and i heard here on the forums that most guys dont use a gasket and just use silicone (which i did). I took the cover off, cleaned the surfaces, applied a bead of silicone and new fluid. Today when i came out to my truck, it was leaking again. How thick is the bead of silicone suppesed to be? How long should i let it cure before i reinstall it? What do yall think? __________________ 1972 Cheyenne Chevrolet red and white 357ci, Vortec heads, GM Performance high rise intake, Comp 268H .454/.454 218/218 110 LSA Quadrajet carb, Flowtech headers, 2.25 40 series HEI, Curve kit, TH 350, 3.07 gears 275/60/15s on 15x8 rallies

11-10-2008, 02:55 PM	#2
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: 12 bolt diff cover leaking leaking rear covers is mostly due to overtightening of the bolts //they requirs 45INCH pounds of torque more causes the holes in the cover to dimple out causing leaks//i still believe in the original style gasket with a light coating of permatex avaition sealer __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

11-10-2008, 03:03 PM	#3
Elephanthead Registered User Join Date: Nov 2008 Location: Carmel, IN Posts: 187	Re: 12 bolt diff cover leaking Use "the right stuff", it is appropriately named gasket in a can. It keeps what you want in and what you don't want in out.

11-10-2008, 08:21 PM	#4
crm318 Alright Alright Alright Join Date: Mar 2004 Location: Midland, Texas Posts: 1,672	Re: 12 bolt diff cover leaking I have a torque wrench i can use. Does that mean that its 3.75 foot pounds? __________________ 1972 Cheyenne Chevrolet red and white 357ci, Vortec heads, GM Performance high rise intake, Comp 268H .454/.454 218/218 110 LSA Quadrajet carb, Flowtech headers, 2.25 40 series HEI, Curve kit, TH 350, 3.07 gears 275/60/15s on 15x8 rallies Last edited by crm318; 11-10-2008 at 08:22 PM.

11-10-2008, 08:26 PM	#5
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: 12 bolt diff cover leaking sorry i dont know the proper way to convert inch pounds to ftpounds//i've got different torque wrenches for bboth __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

11-10-2008, 08:39 PM	#7
leddzepp Moderator Join Date: May 2007 Location: Southern Cal Posts: 19,997	Re: 12 bolt diff cover leaking Very informative...I am having the exact same problem with my 12 bolt rear...I am SURE I have overtightened the bolts. I guess it is just like valve covers.

11-10-2008, 08:46 PM	#8
msgross Registered User Join Date: Jul 2006 Location: Central PA Posts: 12,201	Re: 12 bolt diff cover leaking I take the stock gaskets and put a thin coat of RTV on both sides...and spread it out with my fingers... wouldn't hurt to let it cure for a bit then refill it and go driving... __________________ The Garage: 1968 K-10 SWB - "Project Money Pit" 1996 Z-71 - "huntin rig" 1969 C-10 LWB (SOLD) "Project flip that truck or else" 1993 Passport, F@rd 1-ton (SOLD)"Project Cousin Eddie" My Garage Build "The 1,000 footer" Last edited by msgross; 11-10-2008 at 08:47 PM.

11-10-2008, 08:50 PM	#9
zeeklu Registered User Join Date: Dec 1999 Location: Northwest NJ Posts: 746	Re: 12 bolt diff cover leaking When you clean the surfaces to be sealed ,I use brake clean or something similar so there's no oil residue. I also let the silicone dry over night or a couple of hours before adding oil. Chris

11-10-2008, 10:32 PM	#10
crm318 Alright Alright Alright Join Date: Mar 2004 Location: Midland, Texas Posts: 1,672	Re: 12 bolt diff cover leaking Yea, i think i tightened the hell out of them (well more than 3.75 foot pounds). ill inspect the surfaces and do it correctly tomorrow. Thanks guys. __________________ 1972 Cheyenne Chevrolet red and white 357ci, Vortec heads, GM Performance high rise intake, Comp 268H .454/.454 218/218 110 LSA Quadrajet carb, Flowtech headers, 2.25 40 series HEI, Curve kit, TH 350, 3.07 gears 275/60/15s on 15x8 rallies



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