I'm installing my new 12 bolt Moser, after getting it all painted up I am ready to install the rear Moser cover.

Should I just use the standard paper gasket? Or add high temp RTV and the gasket, or Just RTV?

What are your opinions?

I flaten the bolt "puckers" out of the flange and make sure the cover is straight and level on a flat surface first - then use black RTV to seal it to the housing. I use this procedure on 10/12 bolts and the errant 8.8" I work on, never had one leak there since.
I do still use gaskets on 9" rears with the gasket glued to the center section so it's easy to clean off when I remove them.

All you need is the gasket by itself and it will seal just fine. Don't use rtv instead of the gasket or with the gasket. Do it right the first time and be done with it.

Either will work fine. I like the RTV 'cause it saves me a trip to the parts store.

I've never had luck with those gaskets.

Well, as you can see, there are different opinions on this. I used RTV alone for a few years until I started noticing that some of them had wet spots around the cover after a while. I started using the gasket with a very light coat of sealant on both sides and haven't noticed any wet spots anymore. I hate leaks.

Just a gasket is all I've ever used... Had to clean off sealant many times and it's on both surfaces. Also looks tacky squeezing out between the rearend and the cover even after you wipe it with a rag before it sets up.

Seeing that I never seem to have the gasket on hand when I pull the cover I end up always using RTV.

Another vote for gasket only. I've never had one leak yet. Just pull it down evenly and you should be fine.

I'm sure RTV works too, but for me it's messy and unnecessary on an axle cover.

If you are talking about the big thick Moser aluminum cover, then just use the paper gasket. It is perfectly flat and won't be distorting... ever.

I'd suggest just a gasket too, but if you want, GM sealer has NEVER let me down.
http://www.sdpc2000.com/images/products/7964595_8544386.jpg

I've used both and have had no problem with either. Stamped covers, I clean both mating surfaces with lacquer thinner and apply a 1/8 inch diameter bead continuous about the housing, making a complete circle about the bolts.

Let it "skin" for 15 minutes, then tighten the bolts, 12-15 ft./lbs. Let set overnight to cure, then fill with lube. No problem.

Sometimes with a stamped cover, make it flat and use a gasket, same torque.

lately, OEM, GM, have used RTV for the cover,as seen by my Dana rear axle in truck. I used the same, and no problem, Chrysler's Black RTV, great stuff.

Steve, that is the same GM sealer that I have been using for about 5 years now. It works great and I use it on seals, pinion splines, threads and everything that I need to seal.

As for the RTV, you have to be carefull not to use too much. If it squeezes into the rear end it will make a large bead on the inside. This will eventually break off and go through all of the bearings and gears. I changed the gear ratio in a new Ford truck that had been to the dealership for a rear end inspection. The Ford tech used too much RTV on the cover and it has broken off inside. I cleaned RTV out of all of the bearings and gears. The bearings only had 12,000 miles on them, but they looked like they had over 100,000 miles on them.

Always use a gasket. That is what the factory used. Plus I pretty much garentee it will NOT leak with a little bit of the rtv (light coat on both sides ) you can tighten it good and fill it right away with no fear of leaks.

I drag race alot and need to inspect all the time so I put rtv on one side of the gasket and the other I use grease (the housing machined side) and that makes the gasket last long when removing the cover and changing oil. Hope this all helps, Jim

The ONLY time I never use what the factory design was the manifold end gaskets...THEY suck. I always just use the rtv for that...and never have any leak issues. Good luck.

I am with everyone here that states: use the gasket, skip the RTV.

Yes, RTV "can" seal the cover, but at what cost?

A year ago this past summer I did real axle bearings, seals, and rear brakes on my SO's car. A previous owner/mechanic used RTV for the rear end cover.

I spent more time cleaning the cover and diff housing of RTV then I did doing the axle bearings, seals, brake cylinders, shoes, and drums. Major issue was not having a single little piece fall into the rear. RTV DOES NOT DISSOLVE OR BREAK UP. So little pieces will prevent a roller or ball bearing from from rolling. Boom, failure mode.

I put it back together with a gasket, no sealent. And it still DOES NOT LEAK.

Ever see an engine oil pickup screen clogged with RTV? Ugly sight. Not as bad as the engine bearings though. Thats worse.


Another example of where RTV does not belong: last night I was finishing up stripping a SBC block. As I was checking the drilled/tapped holes, I discovered RTV in a multitude of threaded openings. All of the pan mounts, timing cover mounts, all of the freeze plugs, and other misc locations. What a mess.

Gee, if a pan were to be bolted up and when the bolts bottomed against the RTV, then leaks, is it a gasket failure? NO, we need more RTV!!

Hours, hours I spent digging the RTV out of the blind threaded holes. Along with getting it out of the water jacket freeze plug openings And off of the pan rails, and out of the main cap surfaces, and . . .

Bottom line, be very careful with the use of RTV when building a car.

Bob