Without exception, I use high temp silicone on all paper gaskets for three reasons. 1) it seals better than dry and 2) the gasket peals off in one piece when the parts are taken off next time and 3) it acts as a lubricant during assembly and lets the gasket move slightly during the assembly process. I use a very THIN coating, using two fingers and smearing the sealant as thin as I can get it on both side of the gasket. If you do that it leaves very little on the metal parts to clean up and even then it usually just rolls off.

I wet sanded my chain covers on a piece of glass and found that I exposed more problems than I fixed. Imperfections in the casting required the use of a sealant.

Lindy

Great thread,

I do not see Loctite 573 listed here as mentioned in Wayne's book. For most of non pro builders would this not be a better solution than 574?

A slow cure time would benefit most of us while offering the same finished results as 574?

Am I missing something?

PFM

The shear strength of the 574 is far stronger than that of 573. I used 574 on the main webs/ saddle bearing as has been discussed here. It is to help keep them in place as they don't need to be sealed. I used the Threebond1104/Yamabond on the outer perimeter when it does need to be sealed. No leaks after 3 years.

EXPERIENCE :)
capital letters were intentional

Henry, you are GOOD humor! I laugh out loud every time I read your posts. Tolerance is not your virtue. As a "noob" to the 911, I fully agree with your "experience" statement. I practiced the assembly of my case four times prior to sealing it just to make sure I had the process straight in my head. I have never done a 911 and it is all new to me except similarities to some motorcycle stuff from the past which I draw on for my comment.

Just my two cents worth on the case sealer that I don't think anyone mentioned is that there needs to be material applied to the main webs not only to "glue them together" but also keep the clamped dimensions square. If you put the sealer on the perimeter only and not the webs, the case would end up distorted because the webs would be drawn closer to the crank center-line than the perimeter sealing surfaces. Since both case halves are machined flat with all contacting surfaces even, sealant must be applied to ALL surfaces to keep the case halves square to one another when torqued. I'm sure it can only be measured in thousandths of an inch, but measured never the less.

Lindy

I'm glad you saw the humor but an underlying truth is what makes most humor work.
Purhaps you meant patience not tolerance. I have all the tolerance in the world. I never said "you" didn't have the right the experiment. Pay your money and take your chances as you see fit.
I would admit "I have the patience of a 4 year old. "

This really is a non issue. The case will flex enough upon tightening to compensate for the few .001" clearance difference. Additional stability / shear strength is the true purpose for gluing the webs.

One of the true short comings of the web is the lack of inflection on the communicated words. I enjoy reading your posts as they are coming from a man with unquestionable credentials. I have learned a lot from what you have to say. That said, PFM didn't read back through the thread with regard to 573 vs 574. Your reaction to his post seemed "intolerant" to his unwillingness to read the thread thoroughly, as this information was previously offered elsewhere.

I laugh out loud when I read your posts because you tell it like it is and pull no punches. I like that even if it means you'll probably misinterpret something about this reply and fire back at me.

Lindy

Calling BS on this one. Don't think the shear strength of loctite is really going to effect an engine much.

Although I would agree that the spec is for steel not aluminum, I have to assume that the number would be similar. 1230 psi is hardly an insignificant number when compared to no adhesive. Then add clamping pressure.

The strength of a cured bond is a critical property of any adhesive and many adhesives behave differently in shear to tension. Manufacturers and end users of adhesives use this test method to investigate the tensile shear properties of various bonded assemblies where the bond is between two rigid pieces and the force direction is perpendicular to the bond. The rigid pieces can be a variety of materials including metal, plastics, and composites.

The specimen is tested in a tensile testing machine and consists of two rigid pieces bonded together by the adhesive in a lapped joint. This causes the two ends of the specimen to be offset from the vertical load line of the test. It is critical that the gripping arrangement can accommodate this to ensure a true shear force application.

Many specimens are prepared with tabbed ends that remove the offset. Alternatively, side acting screw grips can be independently adjusted to accommodate the offset. For higher volume testing, many of our pneumatic grips feature the ability to introduce an offset to allow for testing of specimens without tabs.

We recommend reviewing the standard in full to understand the test fixture and results requirements.





http://forums.pelicanparts.com/uploa...1263946580.jpg

88-diamondblue, Thanks for the reply, it was the answer I was looking for.

Lindy,

I did read the thread thank you very much and the question below from John C was ignored.



Anybody used 573 instead of 574?
__________________
John C.

'66 911 #304065
'71 911E PCA H-Stock Club Racer #806
Ex-'88 Carrera (Sold 3/29/02)
Ex-'91 Carrera 2 Cabriolet (Sold 8/20/04)

Henry,

Experience in assembling Porsche engines you have, humility you do not. I remember again now why I do not frequent this board. I see many posts here with your name on them, sometimes sharing information other times advertising your business. I am sure I will work through the task of assembling this motor without any of your help. It may be my first Porsche flat six but it is far from my first engine build.

Regards,

PFM

I must agree with this. I think shuffle pins would be the way to go. What about the loctite squeezing into the bearing shells and into the through bolt oil passages. Any build up on the web can/will make the bore bigger.

Very happy using Loctite 518 instead of 574.

JB

hmmmmm...... Is there a lot of shear load on the webs of an engine.

Line 5 of above assembly instructions are why I don't use 574. You have 20 minutes to completely assemble and torque. Great if you can do it. Sucks if you don't get done in time. Experience counts in this instance. If you have done it enough times to get done, it probably works great. If you require a bit more time then perhaps some alternatives that appear to also work may be more appropriate. And don't say if you can't do it in time you shouldn't be doing it.

+1

The sealant fills the micro-irregularities between the two surfaces, which increases the surface area of the surfaces clamped for a more stable clamp. If it were this super bonding force, it wouldn't be possible to break the bond with a rubber mallet. :D

Jim,

It appears at operating temps and after exposure to oil the 518 is stronger than 574 by a bit. This comes with a bit more working time for those not so experienced.

Thanks


PFM

Henry ....

I have read, maybe here, that use of 574 works well if you can't remove 100% of old sealant. The new 574 merges with the old stuff.

Given that no matter how hard you try you can't remove 100% from both the cam tower and the heads (still installed on engine) how well would Yamabond 1104 work? I ask because I am in the middle of resealing a leaky cam tower. My bad, did not put enough on and it leaked in one place pretty bad.

http://forums.pelicanparts.com/uploa...1263991476.jpg

I tried to dissolve a flake of 574 in a puddle of 574 as a test. After quite a long time never even got soft. I believe that statement is in the factory service manual and I don't believe it will work.

Once again personality overrides ability.
Your search for the humility of man is noble but wasted here.
Your concern should focus on what has been done that actually works.
Theory is wonderful but do you really want to experiment with a 50 hour assembly?

You really need a very s-l-l-o-o-o-o-o-o-w curing bonding agent if it takes you 50 hours to seal the case. :D

574 will only cure in the absence of air under compression. It will not cure under any other circumstance. Any material that gets into the oil through holes or on the bearing surface will be washed away upon start up. As a kid (17 - 28 years old) I was a factory trained Honda mechanic. The cases of most Honda motorcycles are assembled much the same way as a 911 right down to the plain bearings. Honda was emphatic about using case sealant on ALL mating surfaces in order to maintain a square case once torqued. It would not surprise me if the cases of the Honda were machined more accurately than our 911 cases and this detail was more critical. They were made like a Swiss watch.

I value the opinion of Henry Schmidt. While I might take exception to his demeanor, all the while with a smile on my face, I have come to realize that people are who they are no matter what the rest of us might think. I prefer not to shoot myself in the foot by pissing off one of the true "experts" on this site and would sorely miss his input if he just checked out (very unlikely).

One last thought, people pay me to tell them how to do things in my industry; I am an expert there. Henry offers his expertise for free. Nuff said.

Lindy