The Stovebolt Site Forums The Shop Area Engine Shop how would YOU seal it

I am putting my differential back together next week and the last thing I want is an oil leak. I have been told everything from Permetex No.2 to red silicone to no sealer at all. What would YOU use. I hope everyone will try to answer this. Dale

A very sparse amount of silicone. Most people use too much. You don't want any to squeeze out inside and clog things up.

If you are refering to the rear cover & useing a gasket I like to glue the gasket to the cover with a hard drying glue like weatherstrip adhesive & than put a thin coat of RTV silicone on the other side.

A thin bead of silicone will do the job. Just make sure its clean, straight & go around the bolt holes & don't use too much. Also, when you put the bead on let it sit for a while to "skin over" before you install it. Follow those directions & it will be guaranteed not to leak.

I know it's probably overkill,but I use the Hi-Temp red silicone,put it on about the thickness of 3 or 4 playing cards stacked,the full width of the flange,and a wee bit in each bolt hole will make sure the oil doesn't leak past the bolts.and once it's assembled and tightened,I take a rag and wipe off any that squeezes out,then I give it at least a couple of hours to cure up;once it's set like that it won't leak. Also,by letting it cure fully,if you DO get a little too much,it won't break loose to get into the works.As stated before,clean surfaces is critical to a good seal.
I hate to fix things twice.
Speed

Probably doesn't need to be said, but before you go bolting the cover on or tacking the gasket to it, make sure the bolt holes around the cover have been put back to flat. Sometimes when the bolts were tightened too much the cover isn't flat anymore and that causes a leak... A straight edge around the cover will help identify the problem areas, if any.

PS- That goes for all the covers... and with the rear differential I like to use either the RTV Black. There is also a silicon gasket sealant made especially for rear differentials that is pressure activated, so it really bonds when you bolt the cover on. It works wonderfully!

NM15, I think you are talking about "The Right Stuff", it comes in a can much like spray cheese. This will seal anything! I used some on a Jeep valve cover and bent the cover getting it back off. Its the last sealer you will ever need, just don't get it on you! Joe

I have mentioned this before on this site.

I have used the weather seal method, the Permatex, the silicone - everything - on the rear axle cover of my 37 truck 54 car rear cover and everything, including the ones I just mentioned, leaked. :mad: Maybe I didn't put it on correctly. I'm almost sure I did. None the less it leaked!

Finally I found something that has never leaked, and I have pretty much gone back and resealed everything on the truck with it. I have no leaks except a steering box - and it will be fixed soon!

What is it? :confused:

It is: GM Vehicle Care Gasket Sealing Compound 1#1050026 Gr.8.800. It comes in a can 4" tall and 3 1/4" round with a brush applicator in the top. It states on the can that it: Never Hardens or Dries Out, Temperature Range from -50 degrees F to 400 degrees F, Prevents Corrosion. You just brush it on and what might get inside (very little) mixes with the fluid and is soon basically gone.

What I really like about it, besides that it works, is that when you pull apart an axle cover, oil pan, valve cover, water pump, thermostat housing, etc., it comes apart easily and in some cases the gasket comes off in one piece. That's the REAL DEAL, because all of the other methods require scraping the gasket off or removing it with a cleaning fluid, because it's either glued or siliconed to one or another of the parts.

If you will try it, you will like it! I buy mine at the local Chevrolet house parts counter. I don't remember what it runs in cost, but if it works, it might be OK to pay a little more. I'm on my second can that I bought about two years ago. I built my engine with the first can in 1991 and finally used it up two years ago.

Joe

Garbage Bags and Duct Tape?

I suggested to a female cube-mate of mine a few years ago - who was complaining about the high cost of diapers for her infant daughter and how frequently they needed to be changed - that she use garbage bags with two holes poked in them for legs and copious amounts of duct tape. She didn't see the humor in my suggestion. Her husband thought it was a good idea though.

Seriously, with any sealing surface that you need to make sure doesn't leak, you need to do a couple of things. Make sure both surfaces are consistently flat and level (ie no dimples where the nuts tighten down on the sheetmetal covers). You need a gasket material that won't seep the fluid you are hoping to contain. Most fiber gaskets will seep 80w-90 gear fluid over time. So any gasket material you use must be impermiable to gear oil (like dead soft aluminum or copper). You can also use silicone, but older trucks weren't built to a higher standard that newer trucks were - their sealing surfaces don't mate as well as later ones do. Consequently, you need to make extra sure that the sealing surfaces are extra flat and mate well, as in my first point - if you plan to use silicone. Silicone works well in situations where there are tighter tolerances between mating surfaces, but performance drops off rapidly when you have looser tolerances.
Make sure any plug welds are in good shape - they have a tendency to leak, and may need to be rewelded. Be sure to replace the pinion and axle seals. Make sure both pinion and axle bearings are in good shape - if they have any slop at all, the seals WILL leak.

Dale,
I replaced my diff a while back. I used Permatex Hylomar HPF along with a new gasket. It is a blue paste that is both water and solvent resistant. It's not cheap though appx. $7.00 per tube. I used this stuff on the diff cover and the hubs. No leaks. It is very important that your mating surfaces are clean and smooth-i.e. no nicks or fragments from the old gasket or adhesive.

I've had really good luck on engines and gear housing with Napa blue RTV sensor safe sealant. I guy it in the caulking gun size tubes. (About $10) I clean the mating surfaces so they are free of oil and old gasket material. Then I wipe the surfaces with lacquer thinner to get off the oil film. That allows the RTV to really get a grip. No leaks if put on properly. It's amazing stuff. You can save a lot of money on gaskets if you use it properly.