RTV tips?

I've not had good luck in the past getting RTV to seal on the diffs.... anyone have tips for getting a good seal with that stuff?

Also, what type (color) RTV should I use? I think I have just about all of them in my garage to choose from.

Also, I just bought this '93 Country edition XJ.... is this just 75/90 gear oil?

Check the differential carrier for clutches (should be a pic that was posted on here recently,) which would indicate an LSD, and the need for Friction Modifier. If you're not sure, buy it anyhow, since it won't harm anything.

Use a paper gasket - I've never used RTV on gaskets, and have no trouble.

A couple more hints -
Don't use that blue crap - I don't know why it's still out there. I use Black (general purpose,) Red (higher temperatures,) and Copper (Exhaust and self-grounding sensors.) Don't bother with anything else.
Don't throw away that little nozzle you get with the thing - I've got a boxful, and they come in handy now and again. Also, if you end up using the whole tube on a job or three and don't put the cap back on, save a few of those as well...

5-90

So you use paper with the RTV? Or just paper?

Paper only. Make sure the sealing surfaces are clean - use Scotch-Brite if they aren't.

The gasket paper "swells" slightly once it gets wet, finishing the job of sealing. Just take a moment to make sure there aren't any significant defects (gouges, nicks, whatever) in the mating surfaces, and you'll be all right.

5-90

5-90 said:

Don't use that blue crap - I don't know why it's still out there. I use Black (general purpose,) Red (higher temperatures,) and Copper (Exhaust and self-grounding sensors.) Don't bother with anything else.
5-90

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Whats wrong with the blue? I've used on on many occasions and never had any problems with it...

This stuff:
(Permatex® Sensor-Safe Blue RTV Silicone Gasket Maker)

I agree with 5-90 on the use of gaskets. Far superior to RTV for a seal. Just remember to prep & clean the are first as this is the most important step. If you change you diff fluids often you may want to look into a set of lube locker gaskets as they are reusable.

Really? Damn Blue RTV never has worked worth spit for me. Maybe I'm just lucky - but I quit using it a dozen years ago or so. Items I keep on hand for sealing...

RTV Black
RTV Red
RTV Copper
Harvey's Pipe Dope (PTFE paste)
LocTite #518 Gasket Eliminator (this stuff REALLY works - but it's spendy. I keep it around as a "weapon of last resort.")
LocTite #545 Hydraulic Sealant

That's the stuff I can think off offhand. For threadlockers, I have:

LocTite #222 (small screws and screws that get removed regularly)
LocTite #242 (Other screws and stuff I'd like to nail down good)
LocTite #271 (Exhaust Manifold Hardware - nothing else will stand the heat)
Clear nail polish (for locking adjustment screws - best stuff going.)
White nail polish (for replacing the clear in the event I run out, or to highlight markings)
LocTite #640 Sleeve Retainer (Rarely used - I haven't opened it in a couple of years. However, if I want to nail something down REALLY good, this comes out!)
Nickel/Aluminum based anti-seize. General purpose stuff.
Copper based anti-seize. High temperature, high endurance stuff.

Bolts I expect to get wet (water pump, thermostat housing, and the like) get coated with a thin layer of RTV Black or PTFE paste, it saves corrosion and pitting. Better, if I can, is to replace them with brass or CRES. They didn't do that at the factory because both cost more - but damn the cost! I build for reliability.

I really should write all this stuff up as well. I'm taking the summer off from school this year, so I'll probably do it in a few weeks...

5-90

All Chrysler service manuals call for the use of RTV.
Factory calls for use of High Temp RTV, Permatex Copper works just fine.
Clean make sure the axle is free of fluid. I have used a rag to clean it out.
Prep both the cover well. Make sure no old RTV is present, and no oil contamination. I use paint thinner to prep the surfaces.
Lay a 1/8" or a smidge larger bead of RTV on the mating surface of the cover in one continous pour. When you get to a bolt hole, apply around the hole.
Let sit a minute or two.
Take two bolts, and stick them through opposing holes in the cover. Now, without smearing the RTV all over, mate the cover with the axle using the bolts as guides.
Install the rest of the cover bolts tighten to "snug".
Walk away while the RTV dries.
Resnug bolts after RTV is dry.

Fill with your favorite rear end fluid and add modifier if a Limited Slip.
Most parts dealers have no clue what "Friction modifier" is, so get it from your Jeep, Dodge, or Ford dealer. I suspect Chevy dealers have it also, but I don't go to those
You will know it when you have it. $6 of the smelliest stuff you can find on the planet, but it works.

Zuki-Ron said:

All Chrysler service manuals call for the use of RTV.
Factory calls for use of High Temp RTV, Permatex Copper works just fine.
Clean make sure the axle is free of fluid. I have used a rag to clean it out.
Prep both the cover well. Make sure no old RTV is present, and no oil contamination. I use paint thinner to prep the surfaces.
Lay a 1/8" or a smidge larger bead of RTV on the mating surface of the cover in one continous pour. When you get to a bolt hole, apply around the hole.
Let sit a minute or two.
Take two bolts, and stick them through opposing holes in the cover. Now, without smearing the RTV all over, mate the cover with the axle using the bolts as guides.
Install the rest of the cover bolts tighten to "snug".
Walk away while the RTV dries.
Resnug bolts after RTV is dry.

Fill with your favorite rear end fluid and add modifier if a Limited Slip.
Most parts dealers have no clue what "Friction modifier" is, so get it from your Jeep, Dodge, or Ford dealer. I suspect Chevy dealers have it also, but I don't go to those
You will know it when you have it. $6 of the smelliest stuff you can find on the planet, but it works.

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A well-stocked local parts house should also have the stuff - mine does. Just don't bother with the big chains, they hire droids.

If you insist upon using RTV (some do, some don't. I don't, and never have...) make sure you run the bead around the INSIDE of the bolt holes. Seems obvious, I know, but I've seen leaks that people couldn't figure out, but I knew what was going on as soon as I took the cover off...

5-90

5-90 said:

A well-stocked local parts house should also have the stuff - mine does. Just don't bother with the big chains, they hire droids.

If you insist upon using RTV (some do, some don't. I don't, and never have...) make sure you run the bead around the INSIDE of the bolt holes. Seems obvious, I know, but I've seen leaks that people couldn't figure out, but I knew what was going on as soon as I took the cover off...

5-90

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But, I insist Done many of them, none leak. I even did my old 8.75s that way. Again, no problem.

No parts house around here had it, but I'm not in CA Dealer had lot's of it

The language I used was specific. Around, not inside the bolt hole.
I know exactly what you mean to say, and I strugged with how to descibe it, but, if you tell someone to put RTV inside a bolt hole, some maroon will do exactly that. Fat lot of good that will do So my desciption wasted a few CCs of RTV, so what LOL!

Zuki-Ron said:

But, I insist Done many of them, none leak. I even did my old 8.75s that way. Again, no problem.

No parts house around here had it, but I'm not in CA Dealer had lot's of it

The language I used was specific. Around, not inside the bolt hole.
I know exactly what you mean to say, and I strugged with how to descibe it, but, if you tell someone to put RTV inside a bolt hole, some maroon will do exactly that. Fat lot of good that will do So my desciption wasted a few CCs of RTV, so what LOL!

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Yeah - there is a depressing percentage of people about who should not be walking about in public unescorted...

Here in CA, it's a matter of finding the right parts house - I have, and I've been using them for years now. I keep telling people to look for a smaller local - you'll get more out of it, and your prices will steadily improve (it's nice to get jobber, I gotta admit.) And, it becomes possible to get your hands on pretty much anything, after a while.

5-90

one time at band camp when I had to pull my diff cover, and then realized at 1am that i didnt have any silicone, I used rubber cement, just let it get tacky.

but thats just a story, dont listen to me

To get RTV to stick good, the surface needs to be clean and oil free. Carburetor or brake cleaner works real good. Use Black super gasket maker RTV, This one is oil proof. Put an 1/8 to 3/16" bead and make sure to completely seal the bolt holes.

Midnight Krawler said:

To get RTV to stick good, the surface needs to be clean and oil free. Carburetor or brake cleaner works real good. Use Black super gasket maker RTV, This one is oil proof. Put an 1/8 to 3/16" bead and make sure to completely seal the bolt holes.

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I agree, except I use the copper RTV. I have had probs with the black and red. From now on, I will only use the copper RTV.

i did my front diff with blue RTV two months ago let's see how long it lasts
i believe i also used it for valve cover too, oops oh well

I used the copper stuff on my 30/35 last year and didn't have any problems.

If all you can find is RTV then use the black. RTV is sort of obsolete though, much better stuff is available. If you want a good seal use an anaerobic gasket maker. Loctite makes several varieties. Choose a high flex variety with about .015" gap filling capability. Prepare to pay around 20 bones for a 50cc bottle (that will last you a long time). A good auto parts store should have it or look up Applied Industrial products or any John Deere or Cat dealer.

Get everything clean and bone dry, and if your diff cover has ever been overtorqued you might need to sand down the hight spots around the bolt holes.

Dave in Eugene said:

If all you can find is RTV then use the black. RTV is sort of obsolete though, much better stuff is available. If you want a good seal use an anaerobic gasket maker. Loctite makes several varieties. Choose a high flex variety with about .015" gap filling capability. Prepare to pay around 20 bones for a 50cc bottle (that will last you a long time). A good auto parts store should have it or look up Applied Industrial products or any John Deere or Cat dealer.

Get everything clean and bone dry, and if your diff cover has ever been overtorqued you might need to sand down the hight spots around the bolt holes.

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Either that, or you can "ball peen" them. I've got some leftover 1" steel balls that I use for the purpose - came out of a Rzeppa CV joint I worked on several years ago (I keep odd stuff because it comes in handy. I also have a couple dozen old pushrods that make handy alignment pins and handles sometimes...)

If you want an "Anaerobit Gasket Maker" instead of RTV, I highly recommend LocTite #518 Gasket Eliminator - it works well with and without a gasket in place, give good "gap filling," and offers a long working time (which also translates to a long setup time - let it cure overnight.) I don't use it often, because it costs about three times as much as RTV, but it's saved my bacon when I did need it! I do consistently use it on valve cover gaskets, tho, because it's the only thing I've run across that works. Instructions on how I use it are here somewhere...

5-90

5-90 said:

...
LocTite #518 Gasket Eliminator (this stuff REALLY works - but it's spendy. I keep it around as a "weapon of last resort.")...

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Service manual says it should be used when you change the rear main seal to put on the rear bearing cap. I looked for it at a couple of shops around - don't see it. Can I use something else, like some RTV from Permatex ?

Thank you,
Andrey

Yes, you can. I've used RTV Black on a couple of rear main seals without incident - just a touch is all you really need.

The last one I did, I tried not using anything as an experiment. It's still holding - and it's been 18 months or so. So, it seems that the RTV "dot" is more of an "insurance" thing than anything else...

5-90