Adding this here for magnesium case owners - upon removing my head studs that were installed by a builder in Massachusetts in 1991, I noted a bead of silicon sealant around the outside of each hole at the top. Given the talk of head studs pulling on the magnesium case, I expect this was applied to the top 3-4 threads (toward the middle, not the tip) of the stud where it threads into the case in order to prevent moisture from entering and subsequent corrosion to the loaded area/case threads. I've fitted my new headstuds using permatex ultra black in the same manner...makes sense to me.

The proper method for installing head studs is to treat them with a small amount of low/medium hold thread locker. Silicone on head studs is a silly application regardless of the case material.

For this to happen, the oil has to make its way through the oil filter or filters in the later air cooled cars. It is amazing the amount of lint, Dow 111 and sealant junk in the filter at the first and second oil change as the stuff floats free.

One has to wonder why Porsche uses the 1209 in the GT3 catalog and not Loctite as previously. They do specify a 1.5 mm bead and this provides a very small bead at the joint compression line. And the GT3 has only one oil filter which is after the scavenge pump.

Porsche filters generally have a high pressure by pass for cold oil (high viscosity ) situations and it is at these times that we see the potential for silicone worms.
I can't speak intelligently about the GT3 oil system but in the early engines we used to see a tremendous number of engine failures do the silicone worming (bright orange plugs in bearing and squirters).

Ahem, you treat the hole with thread locker, not the stud otherwise you will have air lock issues. You need to consider wet climates outside of your southern Californian home... it makes perfect sense to seal the top of the thread where it enters the case. Magnesium is quite susceptible to corrosion.

Silicon has acetic acid in it, so I think not the best choice for a Mag case in any situation.

Not good for sure.

I hope you're joking... but I can't tell on the internet.

http://www.permatex.com/component/documents/?view=msds&format=raw&filename=22072.pdf&language= 01_USA-English

You wash the stuff off with soap and water. It's basically inert... it's used on magnesium cases around the world.

Try the opposite view. I doubt you got a water-tight seal. Any moisture going in is going to have a tough time getting out.

Afraid that would be quite difficult with WD40, Carb clean and ARP Moly prep.

I'm not talking about that stuff, some silastic silicon compounds I have seen used emit acetic acid vapor on curing and I am not sure how much residual acidity would be left in the thread of the stud joint using it, and not something I would want to think about if the threaded material were magnesium and stressed like a head stud is.

I think if one follows Henry's advice and the Loctite floats to the top of the stud's thread, no significant water is going to get in there, the stud will be tight and Yoda will be happy.

Most silicone sealants are indeed acid curing. The acetic acid cure is that distinct smell most silicones have. But, there are non-acid curing silicones. Permatex ultra black is one of them.

The non-acid curing thing is often mentioned by three piece wheel manufacturers. I guess they don't like the acid on the 6061 aluminum wheel shells?

Thanks Bob.... I had to replace one of my chain housings there were small pin holes from corrosion.

Great info.

Great info! But how come there's no mention anywhere of any Permatex products? As best as I've been able to determine, none of the auto shops (O'Reilly, Autozone, Pepboys) here in the bay area carry any Threebond products (looking for some 1194 - looks like I've got to go to Amazon.com). Are Permatex products just not that good or what?

Yamabond or Hondabond are almost the same as 1194; you can get them down at the motorcycle dealers.

Thanks lindy,
Couple more questions:
1) Do you have to put Yamabond on both surfaces? (vs just 1 with 574)
2) I read that Yamabond starts to develop a skin in about 20 minutes, so you have to work quickly with it also. Is that correct?
3) If Loctite 574 is so hard to remove, are parts also a lot more difficult to separate once you've used it? (Murphy's law runs my life - I just know I'm going to forget something, or whatever, and I'm going to have to pull this or that back apart and redo it...)

Shelf Life?
 

I have read all 14 pages! phew some read.

I have a few engines to build over the next year or two, they are a mixture of aircooled Volkswagen and Porsche.

I have two questions :

1) I plan on using the 4 main sealants, will these be ok on both aluminum and magnesium cases? as I have a mixture to build (911 mag and ali, 356 mag, vw type 1 mag, vw type 4 ali)

2) ive read that the 1184 superseedes the 1194 which superseeded the 1104, and the 1215 for the 1211.

Im of course worried about going off piste from the list, which is probally not justified, but im sure you understand me/why!

So i'm asking should I just go for the 11844 and the 1215 or buy 1104 (or 11940 and the 1211 which are both available on ebay...my worry is shelf life of the 1104 and the 1211 which are still available...

thanks in advance

Make it easy on yourself and go to your local Honda motorcycle dealer and buy a 3.5 oz. tube of Hondabond 4. It's around $6 or $7. Yamaha dealers have Yamabond 4 and it's the same stuff. Ever notice how you don't see Honda and Yamaha motorcycles leaking oil?
These are both the latest rebranded Threebond 4 digit whatever. It's grey and cleans up easy with laquer thinner on a rag.
Instructions are on the tube.

I used it on the cam tower to head surfaces and chain case to case surfaces with no paper gaskets and there are no oil leaks anywhere. I spread a thin coat evenly on both surfaces with a short stiff bristle throw away brush and then put the parts together. It dries relatively slowly so you don't have to worry about rushing quickly while carefully spreading it on the cam tower to cylinder head surfaces.

There is a high temp version of the Hondabond 4 that cost more but you don't need it.
Hope that helps and it looks like this...
Pro Honda Hondabond 4 Liquid Gasket - Chaparral Motorsports

Update on the case through bolt ring grease for the brain trust:

http://forums.pelicanparts.com/911-engine-rebuilding-forum/452985-your-opinion-wanted-green-bolt-through-viton-o-rings-rtv.html

Dow Corning reduces tensile strength of Viton by half; Dupont Krytox doesn't. Choose wisely.