.....let's see, there's

Permatex:

black - thier best, high heat app's

red - high heat app's

silver - sensor safe(?)

blue - er, blue

gonna change my rear diff. gear oil

 

I use red for everything but the black is fine as too. I used the red when I changed my diff fluid, I just got a can of undercoat and recoated the diff after I was finished.

 

I used the orange high temp RTV on mine approx. 15,000 miles ago and no problems at all with leaking. Just run a 1/4" bead around the housing insuring to go around the bolt holes and it should seal just fine.

With the orange RTV as soon as I did the bead I bolted it on and right after bolting it on I put the fluid in. After I got the fluid in and cleaned up everything (approx. 15 mins) I took it out for a short 10 mile or so drive. As far as the orange RTV I used it stated to NOT let it set up prior to bolting it togeather so it may depend on what RTV you use if it needs to set-up a bit or not. The tube should have the instructions which tells you what you need to know.

 

thanks for the help.....

 

Just changed mine this weekend. I used the blue rtv. I put a 1/4" bead around the cover and let it sit for about 10 minutes so it would form a "skin" and then installed the cover and filled with fluid. The next day I went on about a 300 mile round trip. So far no leaks.

 

Hello,

I switched all my fluids to synthetic the other day. No problems with the Tranny, Transfer case or front diff. Did the same on my wifes Merc with no problems at all, even the rear diff.

I have a leak in my rear diff on my pickup now. A rather fast one. I used the Permatex Form-a-gasket (blue stuff). I cleaned the surfaces very well....or at least I believe I did. I cleaned and lightly sanded all surfaces and cleaned again.

Directions said to put the gasket material on both the cover plate and the diff housing. I went around the bolt holes also. I may have put more on than I needed. Stuff came out rather fast. It said to let dry till tacky. Well it was over 100 degrees (yes I know I'm in Montana) and the stuff never did get tacky, even after a couple hours. I put it together anyhow and it sat for a day before I used my pickup.

We then went on a couple hundred mile road trip. When I got back the diff was leaking like a sieve. I tried tightening the bolts some more but there was no more left to tighten.

I have since drained the oil slowly out of the diff. I will strain the fluid thru a paint strainer to make sure its free of dirt. It's still clear and looks clean.

Sorry this is so long, but maybe someone can tell me what I did wrong and offer some hints as to what I can do right next time! I was told to buy the Permatex RTV Blue silicon. It says to apply to one surface only. Sound good?

I've switched to synthetics on all my vehicles and this is the first time this has ever happened. Any ideas will be appreciated.

 

When I did mine with the high temp “orange” RTV it also stated to ONLY put it on one side and that’s all I did was the cover itself. It is important to torque the bolts to the right spec. for my truck an 01 the specs for the cover bolts are 28 – 38 foot pounds, which is not a lot.

There are possibly two problems you have that caused the leak. First you may have over tightened some of the cover bolts which caused the cover to “warp” a bit causing a gap somewhere. Second, since you put the RTV on both the cover and rear-end you may have had very uneven surfaces mating (RTV) which caused a gap somewhere.

It is important to insure both the cover surface and rear-end surface are clean and free of any type of debris. Only use the RTV on the cover insuring to run the bead “around” the bolt holes. Make the bead ¼” no more is needed, any more then that and it just runs out AND possible gets squeezed inside the rear-end and may mix in with the fluid. When you run your bead run a single line when you get to a bolt hole run the bead “completely” around the bolt hole.

Then tighten all the cover bolts “only” as tight as the spec calls for, if you try to make them so tight that you can no longer turn the wrench you will defeat the purpose of the RTV acting like a gasket. When you do tighten the cover bolts tighten them in a pattern like you would use for tighten the lug nuts on your tires, a criss–cross pattern to insure the cover gets torqued down properly and evenly.

 

I used the Permatex Ultra Blue , which is sensor safe. I followed this dude's How To Article, minus the real gasket --> http://www.fordf150.net/howto/differentialfluid.php. I did apply Permatex to both the cover and the diff, and I've had no problems. I just let the Permatex sit for 15 minutes before I bolted everything back together.

Like 01 said, be careful not to overtorque your bolts.

 

When it was leaking, I did crank on the bolts quite a bit to try and stop it. Dumb, I know. Too late. Ya think I warped my cover?It's a pretty sturdy piece of metal. If I torque them right this time and go around it like the lugs on a tire, should it cure itself? Or should I try and find a gasket to put on?

Thanks guys. A simple project became a pain in the ***. Seems usual with me.

I also drained the old gear oil (the synthetic I just put in) and was going to strain it thru a paint strainer to clean it. My brother says the if the Permatex stuff was really runny when I put it together and since I used so much that maybe the fluid got contaminated by the Permatex. He says I should use fresh lube....whadya all think? I ordered more stuff but I think I may have ordered only 2 qts. I don't remember. It would be my luck if I did!!

This ain't been my week. Damn fires around here are really messin with my head. So much smoke I couldn't see two blocks last nite. Yesterdays paper said 312,000 Acres burned so far(yesterday) with 0% contained. One Forest Service worker says ...."it's just out of control....mother nature (snow) is the only thing that can help us now".

 

If the Permatex wasn't tacky, you may have had it spread too thin and caused a void/weak spot in the seal when you bolted everything back together. I don't know if your house is air conditioned, maybe you should try applying it to the diff cover and then let it sit inside.

Sorry to hear about the fires, it's a mess out there I hope some relief comes soon.

 

I doubt you actually warped your cover. What I met was warped it in how it was tighten on. Perhaps a better way of explaining it would be to say it was a little bent or bowed in particular areas. Once it is off again it most likely will go back to its original shape, no bows in it ect.

dlb brings up a very good point about possible voids in it due to the RTV being thin in some areas. One thing I am sure you are aware of but will bring up is to insure you don’t get some of the dried RTV in the bead you lay. You know how sometimes when it is dried and you poke a hole in it to use again and sometimes the little dried crap comes off. If that were to happen it (the dried RTV particles) would cause high spots when tightening down the cover and possibly causing voids for the oil to leak out.

The most important thing is to get as even a bead as possible, don’t have to be perfect, just as even as you can get it, and properly tightening the bolts in a pattern and “only” to the spec’d torque values.

 

DC,if you have the 8.8 rear end go to any good parts store and ask for a gasket for a 93 F150 8.8 rear end.I use to know the part number by heart but forgot it.Its the best $6.00 you can invest in the rear end.Oh,just apply a very little bit of RTV to the gasket if you want to.