differential cover leak (after new gasket) - The 1947 - Present Chevrolet & GMC Truck Message Board Network

crm318 · 09-09-2007, 09:23 PM

i changed the fluid in my differential out about 3 months ago. now there are substantial drip spots everywhere i park. when i installed the gasket, i made sure that both surfaces were gasket and sealant free, then i put a layer of black silicon on both sides. the bolts were also tightened in the proper order. what and i do better this time around when i install a new gasket?

va_tlc · 09-09-2007, 09:28 PM

first id try just re-tighten the bolts down again b4 id pull the cover again.... i had the same thing happen. cured it hope it helps

hemihead · 09-09-2007, 09:29 PM

No gasket. Use gasket maker silicon, thick bead, finger tighten all bolts, let silicon set, then snug bolts. Worked one mine.

BCOWANWHEELS · 09-09-2007, 10:03 PM

take cover back off, remove gasket and clean surface good,hammer and dolly all the gasket surface back flat, use starting fluid to clean cover completely, dont touch gasket surface as your finger have oil in your skin, now use starting fluid to spray and clean out diff. now get a tube of (permatex ultra black silicone ). run a good bead completely around cover, take your finger and smooth it out completely around flat gasket surface to about 1/16" to 1/8" thich,( you want it to pooch out when you tighten up cver ) now install cover and tighten bolts up lightly. let set over night. next day gently tighten up bolts with 3/8" ratchet ( dont be a gorilla ) now refill diff. never leak again. oh yea make sure your diff vent hose is clear also.
bob
P.S. DONT USE A GASKET IN RE-ASSEMBLY......

Huck · 09-09-2007, 10:02 PM

The silicon needs to set up pretty good before you tighten the bolts. You also need to make sure the cover is pretty flat or you will never get it sealed right. Most shops today don't use a gasket. They pull the cover, clean it then use a straight edge to make sure it is nice and flat. next they put a nice 1/8" bead around the housing or the cover---let it set up till it is like cheese, then put it in place with the bolts just barely tight---let it set a while longer then tighten hand tight---don't go putting a lot of muscle on them as there is no pressure to deal with ---and you should be fine. Huck

09-09-2007, 09:23 PM	#1
crm318 Alright Alright Alright Join Date: Mar 2004 Location: Midland, Texas Posts: 1,672	differential cover leak (after new gasket) i changed the fluid in my differential out about 3 months ago. now there are substantial drip spots everywhere i park. when i installed the gasket, i made sure that both surfaces were gasket and sealant free, then i put a layer of black silicon on both sides. the bolts were also tightened in the proper order. what and i do better this time around when i install a new gasket? __________________ 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

09-09-2007, 09:28 PM	#2
va_tlc Registered User Join Date: Nov 2005 Location: VIRGINIA Posts: 905	Re: differential cover leak (after new gasket) first id try just re-tighten the bolts down again b4 id pull the cover again.... i had the same thing happen. cured it hope it helps __________________ 1969 rs 1966fastback 1969swbc/10 2006gt 1972swb4x4

09-09-2007, 09:29 PM	#3
hemihead Registered User Join Date: Mar 2007 Location: Estevan, Sask, Canada Posts: 185	Re: differential cover leak (after new gasket) No gasket. Use gasket maker silicon, thick bead, finger tighten all bolts, let silicon set, then snug bolts. Worked one mine. __________________ 1967 SWB C-10, BBC 454, T400, 3.73 posi, 20" Coys 1972 K5 Blazer, SBC 400, 4 spd, 3.73, 6" lift, 35" mud grapplers 2011 Sierra Denali HD, 6.6 L Duramax, RBP 96R rims, leveled and Nitto trail grapplers, 2009 Acura MDX

09-09-2007, 10:03 PM	#4
BCOWANWHEELS Registered User Join Date: Nov 2006 Location: KINGSPORT,TN. Posts: 3,035	Re: differential cover leak (after new gasket) take cover back off, remove gasket and clean surface good,hammer and dolly all the gasket surface back flat, use starting fluid to clean cover completely, dont touch gasket surface as your finger have oil in your skin, now use starting fluid to spray and clean out diff. now get a tube of (permatex ultra black silicone ). run a good bead completely around cover, take your finger and smooth it out completely around flat gasket surface to about 1/16" to 1/8" thich,( you want it to pooch out when you tighten up cver ) now install cover and tighten bolts up lightly. let set over night. next day gently tighten up bolts with 3/8" ratchet ( dont be a gorilla ) now refill diff. never leak again. oh yea make sure your diff vent hose is clear also. bob P.S. DONT USE A GASKET IN RE-ASSEMBLY...... __________________ I BELIEVE IN JOHN 3:16 Last edited by BCOWANWHEELS; 09-09-2007 at 10:04 PM.

09-09-2007, 10:02 PM	#5
Huck Senior Member Join Date: Jun 2001 Location: Shelbyville, KY Posts: 3,269	Re: differential cover leak (after new gasket) The silicon needs to set up pretty good before you tighten the bolts. You also need to make sure the cover is pretty flat or you will never get it sealed right. Most shops today don't use a gasket. They pull the cover, clean it then use a straight edge to make sure it is nice and flat. next they put a nice 1/8" bead around the housing or the cover---let it set up till it is like cheese, then put it in place with the bolts just barely tight---let it set a while longer then tighten hand tight---don't go putting a lot of muscle on them as there is no pressure to deal with ---and you should be fine. Huck

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