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Diffs - Gasket or Black goo stuff ?


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Intersting dilema here .............

Was chatting last night re the front axle rebuild (only started with the ARB blowing up, now involves calipers rebuilt with SS pistons, swivel preload and bearings redone, and other bits :( ) and we got on to the discussions on fitting diffs intio casings.....

I have always used a simple plain genuine diff gasket, no gooo, nothing, then with clean surfaces on both diff and casing fit it with normally new nylocs and do up.

He has told me that LR now use some black goo (its NOT silicon) and says to fit the diffs with this stuff,

I know that things like TDi sumps use this and not gaskets, and that he has said that it sticks like the proverbial etc, and is now what they use for diffs etc as paper gaskets (esp for off road use) tend to start weeping etc, ...........and this won't

Thoughts ?...experiences ?

What do you use and why ?

Paper or black goo ?

Nige

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The stuff you are referring to is RTV sealant. The problem with using it is that if you have to do a repair in the field, then it's difficult to remove the old stuff and re-apply fresh. With a gasket - if you applied grease both sides of it before fitting, then you can re-use it. RTV sealant is a convenience - not an improvement in my opinion. Catflaps sump is supposed to be sealed with the stuff, but I have used a gasket instead.

I do however carry a tube of sealant with me, as it's always a handy emergency repair.

Poor gasket faces also need RTV sealant - as an addition to the gasket that should be there anyway.

Les. :)

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If I remember the reason correctly, I was told to place the gasket on the clean diff pan housuing then shove the diff in and tighten up. No Grease no oil etc. The reason behind this was the oil would then soak into the gasket expanding it and making a tighter seal, gasket goo and grease etc would work against this process.

Can you explain why you should grease them ?

RTV yeash thats the stuff Les, also matey said that getting things apart was "Interesting" and on 300 TDI sumps they have sometimes almost wrecked the sump getting it off and it also takes some cleaning up too,

At least at the mo, the faces of the diff and casing need just a quick clean and wipe with thinners etc, then new gfasket, so that alone is a huge consideration !!

This sort of thing is real simple stuff, but the options and variations that are out there are worth maybe looking at.

My diffs don't leak as such, they just seem after a while to have a "Damp patch" (oooer :blink: ) which is just annoying when you take so much care and trouble to get it as clean as poss and do the job as well as you can etc...

Keep the thoughts coming

Nige

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Flip!!

The proper gasket paper is impregnated with resins to make it oil resistant. If you made a gasket up from an old corn flakes packet for example it'd slowly allow the oil to leak through it as its not oil proof.

The grease has two purposes. Firstly it acts as a sealant. Ideally you should use the heaviest grease you can get hold of. Secondly it also acts as a lubricant and allows the gasket to settle slightly as the parts are tightened. Otherwise you can end up with ripples, tears etc

Finally if you grease the paper gaskets it makes servicing a hell of alot easier - gaskets come off cleanly with no need for hours of scrubbing etc.

I personally hate gasket goo. I will only use it if there is no alternative (eg factory specifies gasket goo) or its a custom part and theres no gasket available.

Check the mating surfaces are undamaged and clean and it wont leak. I've NEVER had a diff gasket leak. Only need for gasket goo and a gasket is if the surfaces are damaged, or particularly troublesome. Only place I do it on my truck is on the large cover plate over the bottom of the transfer box. The surfaces arent particularly good and it always leaks from there otherwise.

And thankyou but all the oil leaks on my truck are from oil seals not gaskets, and all bar the front swivel will be fixed this weekend! :P

Jon

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Jon is right; you can use paper/cornflake packets but the gasket paper/car is the correct stuff as the others will seep oil, albeit at a ver slow rate.

Only place I do it on my truck is on the large cover plate over the bottom of the transfer box.

^^^

I have found out this too - need to remove and slap on salant. :angry:

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I know that things like TDi sumps use this and not gaskets, and that he has said that it sticks like the proverbial etc, and is now what they use for diffs etc as paper gaskets (esp for off road use) tend to start weeping etc, ...........and this won't

Thoughts ?...experiences ?

What do you use and why ?

Paper or black goo ?

Nige

Why does LandRover have to resort to using these types of sealants to reduce oil leaks? The Japs don't.

The only success I have had removing TDI sumps in situ without destroying them is to ignore the factory workshop manual instructions. You cannot work a sharp blade around the joint with all the carp in the way.

Just cook the sealant all the way round with oxy acetelene or a portable butane torch and then the sump can be prized away quite easily.

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I bent the edge of a sump pan trying to sperate the RTV sealant stuff that was holding it on. That's why I didn't use it when I rebuilt the engine on catflap.

Later engines don't give you the option of a gasket unfortunately, but normally I wouldn't use sealant in place of a paper gasket, unless it was an emergency repair or the mating faces were damaged in some way making the use of just a gasket useless.

Les. :)

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Guest diesel_jim

I always use the RTV stuff, works a treat.

Ok, it';s a PITA to get off sometimes, but i (hopefully) don't have to keep stripping and rebuilding broken bits of my truck! :ph34r:

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IIRC from the "4x4 is born" series when they went to the Ashcroft factory they showed a geabox rebuild and they appeared to be using a black sealant (probably RTV) rather than gaskets.

I assume if it's good enough for them then it's good enough for us mere mortals :)

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Paper gasket if available.

The reason that manufacturers use it is probably the same as the reason they will use bulk oil dispensers rather than 1 litre cans of engine oil - convenience. It is easier to have a sealant gun with a 40 gallon drum of RTV feeding it than hundreds and hundreds of paper gaskets. And it means they just have to supply gallons of RTV - a generic item - through their spare parts distribution network, rather than dozens of different sorts of gaskets which are more than likely specific to their vehicles.

I have seen several 300Tdi sumps almost buggered up trying to get them off, and the amount of faffing around with scraping it off diffs etc is too much hassle. Added to that if you have a wiggle in the wrong place when applying sealant then you get a leak and need to do the whole job again....

It isn't really any better - there are LOADS of 300Tdi sumps which leak, often on quite new vehicles.

Problem is that on many newer things there is no gasket available because they are all built with sealant. "Progress" I think they call it <_<

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Brilliant - who'd have thought we could have such a debate on what amounts to paper and glue :lol:

I've always been RTV, but I've got a couple of sheets of gasket paper at home, and I've just bit the bullet and bought a set of hollow punches, so I can make my own gaskets

Once I've used the wife's tounge to cut 'em out of course :lol:

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Silastic or RTV for me every time (except where critical tolerances are involved, or the part much be removed for adjustment frequently). If you are worried about ease of dissasembly, you can lightly coat one mating fact with oil, still seals just as well. And a razor blade removes it easily.

I always seem to have far fewer leaks on my landies then the people I know who use gaskets.

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Righty Ho then...........

I fink ..................... :huh:

I'll go the "Genuine thick papercardboardy gasket mit smear of grease each side" mefod this time

Will report back say 3-4 months as to how it is

Useful input from the forum, will be different to what I have done for years........

Ta All :)

Nige :blush:

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Gaskets plus RTV for me in most places, although on drive members I don't worry about the gaskets, just RTV. Brake cleaner for removing old RTV, a quick spray and it will wipe off.

Paul :)

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