Rear main seal cover/gasket replacement - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

TheBrightSide · 08-04-2025, 01:15 PM

I was looking for a generic replacement for the rear main seal cover, on the LS3 on my Camaro. Looks like GM OEM parts numbers 12633579 and 12639250 will fit? What’s the difference on these? It looks like they fit most LS style 4.8L, 5.3L, 6.0L, and 6.2L V8 engines. I’m just not sure whether the SUV/truck applications are a bit different from the passenger car parts.

Also, should I just replace the rear main seal gasket itself, or the cover gasket as well, while I have my transmission dropped and out? I figured I was gonna eyeball underneath the clutch and flywheel; but since I may be considering replacing those as well, I’m most likely just gonna replace all the rear main seal gaskets for peace of mind…

If anyone knows anything else I should check/replace while I have my trans dropped, please let me know. I’m currently replacing my clutch slave cylinder, and I’m also installing a remote bleeder line on it. Other than that, I can’t really think of anything else I might be missing, apart from a billet release bearing support that I threw onto the new CSC.

InFiD3ViL · 08-04-2025, 08:26 PM

If you already have the trans out I would also do the cover gasket. No point in ignoring that when you are right there.

1JEWLDSSRS · 08-05-2025, 03:41 PM

And a special note from my experience, make sure to be careful when removing the rear cover as it does contact the oil pan gasket on the rear corners. One of my "used to be" techs didn't see that when he replaced my cover and rear main, and in removing the cover, it took a chunk of the oil pan gasket with it and didn't seal back up, soooo I had ANOTHER leak back there after a while! They did fix it for free since it was THEIR fault.. Just had to put some RTV in the spots where the gasket was torn and missing..

TheBrightSide · 08-08-2025, 01:18 AM

Quote:

Originally Posted by 1JEWLDSSRS

And a special note from my experience, make sure to be careful when removing the rear cover as it does contact the oil pan gasket on the rear corners. One of my "used to be" techs didn't see that when he replaced my cover and rear main, and in removing the cover, it took a chunk of the oil pan gasket with it and didn't seal back up, soooo I had ANOTHER leak back there after a while! They did fix it for free since it was THEIR fault.. Just had to put some RTV in the spots where the gasket was torn and missing..

I will keep this in mind. I have my factory oil pan gasket currently leaking from the sides a bit… I remember the oil pan gasket requiring RTV gasket maker on the 4 corners, but I’ll check what might need me to use some gasket maker on the rear section of the oil pan gasket. Should I use Permatex Ultra Gray or Ultra Black? Those are what I’ve used in the past for oil pans.

1JEWLDSSRS · 08-09-2025, 12:20 PM

Quote:

Originally Posted by TheBrightSide

I will keep this in mind. I have my factory oil pan gasket currently leaking from the sides a bit… I remember the oil pan gasket requiring RTV gasket maker on the 4 corners, but I’ll check what might need me to use some gasket maker on the rear section of the oil pan gasket. Should I use Permatex Ultra Gray or Ultra Black? Those are what I’ve used in the past for oil pans.

I'm not sure what they used, but you want it to harden, yet stay "flexible" like the rubber gasket material is on the cover and pan. Not the gooey black pasty crap we used back in the day. The crankcase pressure will blow it out if it gets too much.

Joe.G · 08-10-2025, 09:28 AM

Ultra Black is meant for oil pans, Holds up to Heat and oil better than Grey which more for Water pumps and thermostats and what not. I Have used RTV colors for applications they aren't suggested for and have not had an issue but I try to keep about 10 Different types on hand.

tartagliazl1 · 08-10-2025, 10:01 AM

Not sure on the different covers. Maybe think about replacing the plastic dogbone seal with a new one or a metal one.

08-04-2025, 01:15 PM	#1
TheBrightSide Drives: 2010 Chevy Camaro 2SS coupe (MT) Join Date: Jan 2024 Location: Sacramento, CA - USA Posts: 371	Rear main seal cover/gasket replacement I was looking for a generic replacement for the rear main seal cover, on the LS3 on my Camaro. Looks like GM OEM parts numbers 12633579 and 12639250 will fit? What’s the difference on these? It looks like they fit most LS style 4.8L, 5.3L, 6.0L, and 6.2L V8 engines. I’m just not sure whether the SUV/truck applications are a bit different from the passenger car parts. Also, should I just replace the rear main seal gasket itself, or the cover gasket as well, while I have my transmission dropped and out? I figured I was gonna eyeball underneath the clutch and flywheel; but since I may be considering replacing those as well, I’m most likely just gonna replace all the rear main seal gaskets for peace of mind… If anyone knows anything else I should check/replace while I have my trans dropped, please let me know. I’m currently replacing my clutch slave cylinder, and I’m also installing a remote bleeder line on it. Other than that, I can’t really think of anything else I might be missing, apart from a billet release bearing support that I threw onto the new CSC.

08-04-2025, 08:26 PM	#2
InFiD3ViL Drives: 2010 CGM 2SS/RS LS3 Swapped A6 Join Date: Sep 2016 Location: Spring Hill, FL Posts: 4,737	If you already have the trans out I would also do the cover gasket. No point in ignoring that when you are right there. __________________ 2010 CGM Camaro 2SS LS3 Swapped A6 - GPI LS3 SS1 .647/.638, (224/237, 112 +4, 7º overlap) on CamMotion 8620 core, BTR Platinum .660" Dual Spring kit w/titanium retainers, CHE bronze trunnion upgrade, stock heads milled @ .015, Melling HV 10296 oil pump, TSP 1-7/8" long tube headers (W/Catless Off-road Pipes), Corsa Xtreme 3" Catback, GPI Ported/Rod Mod Intake, Stage 2 Ported Throttle Body, Vararam OTR CAI, Mike Norris Gen 2 catch can + GM 1LE clean side separator, 160º thermostat - Megan Racing adjustable coilovers (lowered 1.75"), MRR M017 10/11" wheels-Tuned by Ryan @ GPI

08-05-2025, 03:41 PM	#3
1JEWLDSSRS Drives: 2011 SS-RS Join Date: May 2011 Location: FLORIDA Posts: 14,034	And a special note from my experience, make sure to be careful when removing the rear cover as it does contact the oil pan gasket on the rear corners. One of my "used to be" techs didn't see that when he replaced my cover and rear main, and in removing the cover, it took a chunk of the oil pan gasket with it and didn't seal back up, soooo I had ANOTHER leak back there after a while! They did fix it for free since it was THEIR fault.. Just had to put some RTV in the spots where the gasket was torn and missing.. __________________ TSP STAGE 3 CAM,231/246 @112 LSA 614/641 LIFT, CIRCLE D 5C-4200-4500 CONVERTER,LOD INTAKE.CORSA EXHAUST. DSS 1 PC DS. PEGASUS SOLID CRADLE MOUNTS. 486RWHP/475RWTQ.LOTS MORE.

08-10-2025, 09:28 AM	#6
Joe.G Drives: 2014 2SS/RS 6SP Ashen Grey Join Date: Aug 2021 Location: NY Posts: 1,763	Ultra Black is meant for oil pans, Holds up to Heat and oil better than Grey which more for Water pumps and thermostats and what not. I Have used RTV colors for applications they aren't suggested for and have not had an issue but I try to keep about 10 Different types on hand. __________________ GM 3.91/TrueTrac OEM ZL1 Rims, 6 Piston Brakes & Side Skirts.ACST4 Splitter/Deflectors NPP M2W,GM Short Throw,GPI Ported Rod Mod,BO White PTB,CAI/JRE Scoop, GC Aluminum DS,Stainless Works Ceramic LTH/HiFlo Cats, Hotckis 1" Springs & Chassis Max Brace BMR Adjustable Swaybars,Trailing Arms, Adjustable Toe Rod, LCA & Z28 UCA Bushings Hendrix Solid Cradle Bushings Pedders Radius Rod Inserts Strut tower brace, Moroso Catch Can,SCT X4 Dynosteve,Remote Clutch reservoir,Hero Smoked Tail and 3rd Brake Light, Diode Dynamic SL1 Fog Lights AeroForce Dual gauge/Autometer pillar mount.

08-10-2025, 10:01 AM	#7
tartagliazl1 Drives: 2013 zl1 vert Join Date: Dec 2018 Location: Rochester, New york Posts: 1,202	Not sure on the different covers. Maybe think about replacing the plastic dogbone seal with a new one or a metal one. __________________ 22% lower/ 2.5 upper/ 2” headers/ cat delete/ x-pipe/ 2 gallon x tank/ 100-3 pump/ fic 1300/ dsx aux kit/ 103mm throttle body/ big gulp 5” intake/ meth kit/ prometh lid injection/FI interchiller/ 160* stat/ ngk-7/ msd wires/ elite catch can/ tsp cam/ Che trunnions/ ported supercharger/ 1/2” lid spacer/ cnc,milled ported heads/ brick mod/BMR toe and trailing arms/ 781hp 748 tq SAE @17.3lb on a loaded dyno.