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gasket question

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fmichaels

fmichaels

Jedi Knight
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so help me out on this ... i have a paper gasket between two metal surfaces ... the gasket absorbs the oil and potentially transfers it through the gasket material out onto the garage floor. If i apply ultrablue sealant, then the gasket could still weep the oil through the paper gasket to the floor ... so why use the gasket at all? if i just used ultrablue, then there is no weepage path for the oil to leak ... what's wrong with this picture ... my transmission wants to know!
 
Bah, paper gaskets do not weep oil. No way.
 
jlaird said:
Bah, paper gaskets do not weep oil. No way.
Click to expand...
I agree with Jack, once those paper fibers are compressed there should be no leaking or weeping. Most water pump gaskets are paper and they don't leak anything if done right and water/glycol is much thinner fluid than gear oil. Are you absolutely sure the surfaces where clean?
 
my point is that if you use only sealant (and a quality sealant at that), that the area between the two metal surfaces should be leak free and tight ... now you do have to make sure the surfaces are clean and that you have the best metal to metal seal as possible, but the gaskets on my transmission are, excuse the pun, paper thin and i figure just using a good sealant should button that tranny up nicely ... skip the gasket!
 
That will work of course if you use the right stuff. New cars have no gaskets it is all sealant but for the head.
 
exactly! ... i am not saying never use a gasket again ... it only seems fair to say that using a quality sealant could potentially reduce the amount of oil these cars leak ... i don't mind a small leak here or there, but it would be nice to keep it manageable. just as an example, i was cleaning one of the tranny access panels last night and the old gasket was soaked through with oil. that tells me there a pathway for oil to get out.
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perhaps i will give this a try since i am sealing two trannies right now ... one with and one without ... fill'm up and sit'm side by side.
 
Be careful, I have seen this done on motorcycle cases and what you run into is the gasket thickness was originally used in figuring end play on shafts and things. If might tighten up things .002-.005 or more.
 
good point and one to consider .... not sure i'm all the way there yet, but these are the things i want to understand ...
 
Like you mentioned earlier, if the metal-to-metal fit is near perfect then just a sealer will work. The two halves of a Volkswagen crankcase are put together that way, with just a thin coat of sealant. And that joint never leaks. The motor was designed for that though. On parts that were designed for a gasket, you might be taking chances. I agree with Jack too. I've never seen a paper gasket weep unless it was damaged or not properly compressed.

Bayless
 
Miss Agatha has no leaks, none except the rear main. But then that was designed in.
 
perhaps i am too aggressive to say a gasket weeps ... don't think i ever actually saw that myself, but they can absorb and therefore provide a means for the oil to exit a sealed area. i understand the need for gaskets on things like the valve cover or engine pan, but for surfaces like access panels on the tranny, the ever elusive axle seals, even the diff to pumpkin seal. they all seem to have some potential to benefit from sealant alone.
 
Is supose to absorb oil or fluid and swell up, that's what makes it tight. Hehe, I use both, gasket and sealant, seems to work here in Niceville.
 
Day was, pre-RTV, before installing those thin paper gaskets we'd pre-oil 'em! No leaks then, either. The lube will not propagate thru the compressed fibers. And consider the statement with regard to tolerances. Case covers wouldnt matter, but the front shaft seal cover may have a need to be "out" the thickness of the gasket. Just food fer thought.
 
"""""""perhaps i am too aggressive to say a gasket weeps ... don't think i ever actually saw that myself, but they can absorb and therefore provide a means for the oil to exit a sealed area. """""""

It doesn't weep...the oil can actually migrate thru a gasket. This happens for example, on automatic transmission pans where modern auto trans fluid migrates thru a gasket and is helped along with a stamped steel oil pan with screws about 3" apart.

"""""""... so why use the gasket at all? """"""""

So as to take up irregularities and voids in the mating faces. Also the gasket serves as a "carrier" for the sealant that is used.

Using a gasket you call "paper" on the trans side cover is possibly porous to some degree. You want to use Permatex Aviation Form a Gasket or GM Brown sealer on a porous gasket. Coat and soak the gasket by brushing on each side.

If this is a rib case cover I use Hylomar and no gasket. BUT..you have to use only Valco Hylomar or eqivaqlent as they have the proper drying agents and Permatex or Loctite do not have the right agents.


""""""if i just used ultrablue, """"""

you should be using Permatex 599BR ultra GREY.

Also get a "tube grip" made by Valco.
 
IMO; Gaskets can provide capillary seepage if not tight and... That requires the fluid to be viscous enough to travel through the fibers of the gasket. Sealer will fill deviations in the mating surfaces and will not allow seepage through the sealer. The problem is that when tightened, the gasket is under compression. The sealer is not. The sealer makes a seal to the surface by gluing to it. If the surface is not completely clean, no sticking and no seal.
 
Bayless said:
Like you mentioned earlier, if the metal-to-metal fit is near perfect then just a sealer will work. The two halves of a Volkswagen crankcase are put together that way, with just a thin coat of sealant. And that joint never leaks. The motor was designed for that though. On parts that were designed for a gasket, you might be taking chances. I agree with Jack too. I've never seen a paper gasket weep unless it was damaged or not properly compressed.

Bayless
Click to expand...
Subaru engine cases are the same way, and so were a lot of the harley cases. In those cases a gasket could cause problems the other way with tolerances. I guess it all depends on the design. if it had a gasket and i had one I would put one back, if I didn't have one I would have to think about it before using the gasket eliminator or whatever.
 
A couple points....

The purpose of any gasket is to reduce leakage by filling up the small gaps and irregularities in two mating surfaces. That's how they work. Oiling a paper gasket actually helps it seal by softening it and making it more pliable.

All gaskets leak, to some degree. People who do high-vacuum work know that even elastomer o-rings are subject to air diffusion through them. The design of any gasketed joint therefore takes into account the materials to be sealed, their pressure, and the nature of the mating surfaces. Paper gaskets are generally used where the substance is not too viscous and pressures are low. In any case, thought, the gasket does the sealing; a sealer may help, but it doesn't provide the sealing by itself.

I have no doubt that, in many applications, some kind of sealer without a gasket is fine. But the joint and material have to be right for this, and the mechanical and chemical characteristics of the sealer appropriate as well. I wouldn't just use a sealer and dispense with the paper gasket unless I was sure I knew all the considerations, or knew from some other source of information (e.g., other people's experience) that it would work.

I also have no doubt that many of the gasketed joints in our cars are extraordinarily poorly designed, and the amount of leakage from them is pretty solid evidence of that. Still, I wouldn't experiment blindly, even with these joints. They could be made a lot worse, and, after all, would a Sprite have the same charm if it didn't leak? Seems unthinkable, to me.
 
Sooo... If I may hijack this thread for a bit... it turns out that due to an oversight, I am ready to put my motor back together, but I have no oil pan gasket. I REFUSE to pay $10 shipping and handling for a $5 gasket. Therefore, I am wondering if Permatex #2 (the black gunk) would be good enough to seal the oil pan. What do you guys think?
 
Think I would do it right, and order something else as well.

You need the cork end peices as well as the side gaskets.
 
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