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I am assemblying the split crankcase haves on a 1973 Merc 25ss and looking for comments on the sealant to use on the machined alum surface.
Permatex has 2 possibilities:
1) An anaerobic sealer (same as Loctite anaerobic #518):
http://www.permatex.com/products/Aut...et_Maker_b.htm
2) Hylomar sealant (not anaerobic) non hardening:
http://www.permatex.com/products/Aut...ge_Sealant.htm
I used to use 3M 847 but haven't found it locally and Inet has rediculous S&H for a small tube.
LocTite 518.
Do not put it on too thickly. Just a light pinkish coating on a clean surface, any ooze on torquing the cover halves indicates it was too thick. What we're trying to achieve here is to seal the cover without 'floating' it on a 'formed in place' shim. We want a perfect metal to metal seal, but because we can't have that, we add just enough sealer to fill the microscopic voids and imperfections.
To remove later, Zip Strip paint remover lifts it right off.
One more time, avoid the Mod fallacy of if some is good, more is better, then way too much must be just right!
Jerry
----------------------Quote:
Originally Posted by Trident
Thanks for the recommendation since I wasn't sure if an anaerobic or non anaerobic sealant should be used. .
I looked up the Product Data Sheets and they indicate that Locktite 518 is the same chemical as the Permatex Anaerobic sealant 51813. So I suppose either is OK. Wasn't Permatex a division of Loctite and they split in the late 90's but still maintain similiar products?
http://www.permatex.com/documents/td...tive/51813.pdf
http://tds.loctite.com/tds5/docs/518-EN.pdf
So anybody needing an anaerobic sealant can use either one.
nice:cool:Quote:
LocTite 518.
Do not put it on too thickly. Just a light pinkish coating on a clean surface, any ooze on torquing the cover halves indicates it was too thick. What we're trying to achieve here is to seal the cover without 'floating' it on a 'formed in place' shim. We want a perfect metal to metal seal, but because we can't have that, we add just enough sealer to fill the microscopic voids and imperfections.
To remove later, Zip Strip paint remover lifts it right off.
One more time, avoid the Mod fallacy of if some is good, more is better, then way too much must be just right!
Jerry
JerryQuote:
Originally Posted by Trident
Having never used this sealer I need to make sure of the process. I plan to clean both contact surfaces with lacquer thinner or ?, and then use a continuous bead as noted on the Loctite and Permatex instructions, or as you indicate spread on a very thin film (on one side only?) using say a razor blade to spread it on the surface and then immediatly bolt it together.
Pete
LocTite 518: OK, here's my method... first, I clean the surfaces with a good solvent like acetone, or if there was old sealer, use Zip Strip, then acetone. Next, in a class where its permitted, I'd pull the dowel pins and lightly draw file or stone the mating surfaces to remove any dings or high spots. See the cleaned up area around the dowel pin holes? Replace pins.
Then, I put a series of little dots of the sealer all along the joint suface. No speader tool, that would leave too much. Just use your finger tip to 'stipple' the sealer to blend all the dots. When done, the sealer should be just a fine, fine coating of overlapping finger prints, and have a faint reddish/pink color. Deep red is way too thick. Remember, the factory actually silk screen prints the sealer on new motors. Very faint, even coating.
For big jobs, you can also use a small foam paint roller, but that sucks up a lot of material. On small motors, just give 'em the finger!
Remember, we really want a perfect metal to metal joint. As we can't get that, we add just enough sealer to fill the microscopic imperfections. These sealers are thick enough, that if you use too much, the cover 'floats' on a layer of sealer, making a formed in place shim. Of course, then your line bore is out of round by that thickness, and the crank train rattles around. Don't want that!
Hope this helps.
Jerry Wienandt
Trident Racing
Should also have mentioned, there is no big hurry to bolt it together and torque it immediately. Take your time, do it right, carefully, get your bearing caps lined up, etc, and bolt 'er up. No panic. If you get it buttoned up a few minutes after coating, you're fine, as the sealer doesn't cure until its deprived of air, in the presence of metal. Any little extra at the edge of one half, where it doesn't contact the other half, like around the fixture holes, etc, can be wiped off with a Q-tip and acetone after you're all done. I clean up all around the joint line, just for neat appearance, but if you did this right, there should be almost nothing to clean up!
Jerry
JerryQuote:
Originally Posted by Trident
That description says it all. The dot method and fingerprints is a creative way to get a relatively uniform spread of the sealer. I assume from your description to apply to one side only like my outer crank half that does not have the locating pins thus easier to stipple in that area.
Thanks :)
Pete