okay, case sealer again
 

I did a search and read all the threads I could find, but I still have a question. Whether I use loctite 574, 573 or 518, all the MSDS sheets say to apply as a continuous bead or screen printing.

http://www.loctite.com/int_henkel/loctite_us/index.cfm?&pageid=114&layout=3

Wayne recommends using acid brush to essentially paint a thin layer of 574 on the case half. Is this effectively "screen printing"?

Some people want to see some material squeeze out of the case and inside also. I would tend to follow manufacturer's instructions and just use a bead and assemble. I would not worry if there was no squeeze out. This is on a 92 C2 964 engine.

Thanks for any comments.

So I decided to try some beads
1-about 1/8 inch bead on 2 places
http://forums.pelicanparts.com/uploa...1110427972.jpg
2 - close view of web area
http://forums.pelicanparts.com/uploa...1110428102.jpg
3- after lowering case half onto other, no nuts. shows squeeze out
http://forums.pelicanparts.com/uploa...1110428207.jpg
4-overall view of squeeze out
http://forums.pelicanparts.com/uploa...1110428354.jpg
5-cut amount by about half
http://forums.pelicanparts.com/uploa...1110428400.jpg
6- squeeze out only at top
http://forums.pelicanparts.com/uploa...1110428434.jpg
7- close ups
http://forums.pelicanparts.com/uploa...1110428463.jpg http://forums.pelicanparts.com/uploa...1110428479.jpg
So I think I will use a thin bead around circumference, and a thick bead on webs.

Anyone done this using a bead and not a thin spread of sealant?

it's suggested that 574 be applied using a small roller, if anyone still wants to chance it. don't know about the red stuff.

Interesting test and photos. Steve. What sealant did you use?

Do you think it's fair to assume that the squeeze out will be consistent around the entire perimeter and across all the webs? If so, your decision on bead thickness would seem to be okay. But if elsewhere on the case the degree of squeeze out is different (like maybe the opposite of what you observed in your test), might you end up with too little sealant in one place and too much in another? I would think that generally too much is better than too little, but in that first photo, you certainly had a lot of goo squeeze out. Do you, or does anyone, know have any way of quantifying how much is appropriate? My guess is that it's one of those "feel" and "experience" things. But I appreciate seeing the results of your test.

With 574 a thin layer is good. A thick layer is bad and will cause leaks. Unfortunately I know this from experience. :rolleyes:
Remember that all but a little of whatever you put on is going squeeze out.

I know a famous engine builder who smears 574 on with his finger. One advantage of putting it on with a roller is that it doesn't smear it into the holes.

I use 574 (smeared thin) on the webs around the main bearing. My thinking is that it might be important in duplicating the factory bearing crush and because those thru bolt holes are pressurize oil passages and I don't want them to leak.

-Chris

what if the 574 on the thru-bolt/main bearing webs sets up early/thick??? and why would you need it there in the first place?

That's a scary thought isn't it (thicking early at the case webs)? I started using 574 on the webs because Henry Schmidt recommended it and I could swear Greg Brown did. After reviewing Greg's article on case sealing in 2002 Winter POC newletter (page 24 of 26 pdf, page 46 in print) I see that it was a figment of my imagination. (Wouldn't be the first Senior Moment for me.) A review of the factory manuals doesn't recommend it either.
I guess I won't be doing that anymore.
Thanks John!
-Chris

we should have a poll of the people on this site who have had a problem with it. there are several. there are many other sealers around that work, for sure, to take a chance with this stuff, IMO.

The red is Loctite 518. I think one needs just a little to do the job. In missile hardware I have run across the common misconception that if a little is good, then more is better. Usually in sealant and o-ring greases, it is worse to add more.

After further discussions with some local guys, my plan is to use the red Loctite 518, apply very sparingly to case perimeter using a cutoff acid brush, and not apply internally. I'll take pictures this weekend.

Chris,

I was very interested by the POC newsletter article. You're right, it doesn't specifically address whether the author (Greg Brown) condones using sealant on the bearing webs. But from my read, I think it may have been implied. The article suggests using 574, applying it with a roller, and tightening the perimeter bolts first. And he talks about following the factory manual. Have you consulted that recently to see exactly what it says with respect to this issue? I may do that tonight, but I only have the ancient volumes, for engines up to 78 or so.

Steve, what's a cutoff acid brush?

http://www.pelicanparts.com/cgi-bin/wizards/Parts_Wizard.cgi?command=step2&wizard_root=911_eng ine_rebuild

look down the page, it is the type of brush that I use to use to apply that jelly like acid for brazing

then cut off all except for a quarter inch of length, carefully pull any loose fibers out.

The '84-89 Carrera manual says to apply it to sealing surface.
The 964 manual is less specific; it just says to apply it to case half.
-Chris

more info

http://tds.loctite.com/tds5/docs/518-EN.pdf
http://tds.loctite.com/tds5/docs/573-EN.pdf
http://tds.loctite.com/tds5/docs/574-EN.pdf

Link was not a direct feed, these are the MSDS. Looks like 518 has significantly higher shear strength over time.

THe red stuff works just as good as the orange stuff, if applied the same way. Hard to get to much, because it squeezes out, and if it does it won't hurt anything, couse it won't harden or clog up anything. I suspect that the red stuff is actually better than the orange stuff but have no data to prove it.

GM actuallly used the stuff for its Cadillac northstar engine, but has recently switched to the same stuff one of my Porsche full time mechanics use, ie grey rtv silicone sealant. Seems that the stuff actually works in place of the orange and red stuff, only better.

I personally haven't the guts to try it but the Porsche mechanic swears by it.

Next rebuild of my race engine I will try it and see what happens.

it does, eh? well, maybe sometimes. read the other recent 574 thread.

http://forums.pelicanparts.com/911-engine-rebuilding-forum/209697-loctite-574-thickness.html

"I'll save money by buying a cheap 911 that needs some work."

"The factory uses 574 and all the books say to use it. It must work."

Some things you just need to discover for yourself I think. :D

-Chris

Hey Steve,

Drifting a bit from your original inquiry...

I've been wondering why your aluminum case looks all nice and shiny (like aluminum should) while mine (78 3.3) looks flat gray and oxidized, both inside and out, like it's made of magnesium. And mine has been thoroughly cleaned, just like yours. Have you (or has anyone) seen this before? It's not that I really need to have it all shiny, as long as it's surgically clean, and I'm not going to go to any heroic lengths to polish it, but I must say I'd like to see it shine more like yours.

Is there a reason Dow 730 is not on your list of sealants?

Jim

i used 730 for a while, and the only thing i didn't like about it was that it skinned over pretty quickly, like within a few minutes, so it tended not to adhere as well to the case half that it wasn't applied to. the cost was another minor issue.

I don't think it was a sealant problem. Something more likely held the case apart. I guess one possibility is that the case was assembled and not immediately torqued togather letting the sealant dry thick, in any case there should be no way for the sealant itself the be the cause of the problem.

I agree with the slow restoration guy about checking case halves. Any sealant that covers up improperly mated cases is no bargain it just permits a more expensive failure later.