The Stovebolt Site Forums The Parking Lot Big Bolts Gasket or black silicone?

I'm just about finished with the rear end on my 6400. The end caps on the end of the axle and the "pumpkin cover", can I use black silicone or does it have to be a gasket. Not sure if I'll find matching gaskets. Thanks all!

I used black on the pumpkin cover and the gaskets on the axle ends.

Hy mummdogg,the Fel-Pro numbers are RDS5049 for the diff , and RDS4062 for the cover side on a single speed rear axle, and the two speed numbers are RDS5050 for the cover side, and RDS11855 for the diff side, that is providing no one has swapped rear axles in the last 57 years, hope that helps.

Consider the Permatex product "The Right Stuff" that comes in a standard caulking tube. It is a rubber elastomer product that does not require a gasket. In my experience it seals much better than silicone without any leaks and is quick and easy to apply. The only downside is it is a bit hard to remove the sealed part due to its adhesive properties.

being in the steam generation business i like a real gasket on everything. im not a fan of snot(unless its coming out of my nose) but in certain applications i will use it on my trucks. the problems with gaskets is they tend to stick to one or both sides of what is pressing against them. when the time comes to seperate them, a couple of things can happened but ultimely the the gasket is destroyed. some people like to glue (gasket sealer) one side to a paticular surface for ease of removal but maintaining its position for reassembly. there is no guarentee that the gasket still wont fail. what we do is to add never seize to both sides of the gasket and the mating surfaces. even under extreme pressure (process) and temp the gaskets don't stick to the mating surfaces nor are they detroyed in the process should disassembly take place. i like to do this on uncommon gaskets such as axle flanges where they are hard to find replacements.

I like the gorilla snot on the pumkin cover after the gasket surfaces are clean as a whistle. The gasket will tend to weep. Not too often does the rear end lube get changed.

I do like the gaskets on the outside flanges.

I use a gasket anywhere one was originally used, and most often use Permatex #2 lightly on both sides, just enough to not ooze out. (knock on wood, but so far my new "Driptroit" Diesel hasn't dripped..)

For valve cover gaskets I use contact cement and stick the gasket to the cover, and nothing on the other side. It's stuck in pace and reusable for many valve adjustments.

Some if not all newer rear axles use some type of silicone goop on the housings, I've used it too and it works.
But I still prefer to use a gasket if one was used originally.

Grigg

I always use a gasket if one is available or make my own at times. I've found that if you clean the bolt holes and the bolts real good sometimes a bit of sealer on the threads of the bolt will help with the seepage that if often noticed.

Thanks to all. I too would rather use a gasket if possible. I really haven't had time to see if any were available yet. Thanks 3B for the numbers. I used the black silicone in the past with good results. I figured since the rear axle isn't pressurized or heated, it shouldn't matter, but I wanted to ask the tribal elders first. The gaskets on the outside caps are gonna be fun to cut if I decide to make my own!

Howdy mummdogg,

A lot of times I have to make my own gaskets to save time and money for my customers. Harbor Freight has a set of cutout punches to make the bolt holes. It's been a while since I bought the set, but they weren't more than $10. NAPA has rolls of gasket material and the left over will come in handy later. On machined surfaces I use a ball peen hammer to cut the gasket against the part, and anything else marker and scissors. Who said kindergarden's over! Torque your bolts for even squish and a gasket's only enemy will be heat or age which ever comes first.

If you can get a gasket, smear a THIN layer of black goo on one side of the gasket and let it fully cure.
Then put a THIN smear on the opposite side and allow it to cure until tacky.
Assemble the two parts finger tight and allow an extra hour or so to fully cure and then torque up the bolts.
This makes a great seal, yet allows the parts to be disassembled without wrecking the gasket.

If you run without a gasket, coat both surfaces evenly and allow to 3/4 cure.
Assemble the parts finger tight and allow full cure, then torque to specs.
This creates a good even seal and will come apart with ease, possibly with the black goo "Gasket" in one piece.

I used to use that method,
Now I use Permatex #2 on the gasket, a thin smear both sides, just enough to not ooze out.
I'm having much better results with the Permatex than I had with the silicone.

Grigg

I'm with you there Grigg!
It's a bit hard to translate the actual product you are all talking about.
Here we have a product called "Ultra-Blue".
It is not a silicone based sealant, but is the best compound to use on all things mechanical that need sealing.

At the end of the day, the method still remains the same!
Hopefully it helps out

Here's the info on Permatex #2
it's a "Slow-drying, non-hardening sealant designed for sealing cut gaskets and stamped parts. Allows for easy disassembly if required. Temperature range -65°F to 400°F (-54°C to 204°C); resists common shop fluids and fuels. Use where sealing is more important than adhesion."
Looks like tooth paste but black and a little stickier.

Grigg

we used it in the navy deep down in the propulsion plants. we'd get in jumbo tubes and used it on almost everything. the part that its "non hardening" is B.S. but then we went over the upper temp range by 2. when dealing with 1200 psi @950* steam you want something that does the job and ole #2 did it. we hated it and i now only use it in certain applications because i still hate it but i will choose this over snot anyday.

..... I must admit that for years Permatex is all that I would ever use...and I still prefer it over most stuff.
But, what I think we're really saying is that there is a better choice today than years ago. Products today are more specific to one job..... its just tough sometimes deciphering what it is really the best at since all the manufacturers want you to think THEIR product is the cure for all ills!

.... but I still love my Permatex products!!