okay, case sealer again

[adomakin]

trouble is steve, its not priceless. id give thousands!

Andy

[adomakin]

you know what its like though, i just not happy with my 9, id love to be into double figures..........

[snowman]

I have rethought my possible use of an RTV on my race car. CSTREIT statement that you can't trust anything that can harden inside the case brought me back to hard reality, one must use an anerobic sealant. One speck of anything inside an oil squirter and its no longer functional.

[ken martin]

John Walker, what should I use to apply Dirko to the case halves, how thick, how much time will I have?
thanks
KM

[john walker's workshop]

your finger works well to apply a thin smear. you just don't want a big ol' bead squeezing out, so use with discretion. you can go have lunch and it will probably still be sticky enough to use when you get back. snowman, anything inside the case would have to be picked up by the scavenge pump and pass thru the oil filter before it could get back into an oil passage to plug up a squirter.

[stevepaa]

Update:
So I applied a thin bead loctite 518 to the case half wo studs

then smeared it thin with a acid brush, chopped short

assembled, and tightened perimeter nuts first, then installed thru bolts very quickly without o-rings to get it together very quickly, here are pics of front and rear squeezeout,

here is shot of web inside and squeezeout

and top

waited 24 hours and then installed 0-ring on thru bolts one bolt at a time

[Rob 930]

Stevepaa,

Thanks for the photos and description of what you did. Please keep us posted after you have it running and tell us whether you're leak free. A few questions: What's an acid brush? What did you do for sealant around the No. 8 main bearing (which seems to be problematic sometimes)? What did you use for assembly lube on the bearings? For engine bearings, I've been advised to use engine oil, not moly lube, but I've wondered how others do it.

[stevepaa]

see page one for link to acid brush.
No sealant whatsoever around #8. I only applied Dow Corning O-ring lubricant to the o-ring. I was very concerned that anything else might squeeze into o-ring groove or the small oil return passageway, thereby hindering proper o-ring movement and sealage, or perhaps block oil return passage.
Used Moly assembly lube on bearing. Have always used it on my previous rebuilds, Porsche 912, MGA1600, BMW2002, Chevy350, Landcruiser 6, Mercury 4 banger.

[ChrisBennet]

Originally posted by stevepaa
see page one for link to acid brush.
No sealant whatsoever around #8. I only applied Dow Corning O-ring lubricant to the o-ring. I was very concerned that anything else might squeeze into o-ring groove or the small oil return passageway, thereby hindering proper o-ring movement and sealage, or perhaps block oil return passage.
Used Moly assembly lube on bearing. Have always used it on my previous rebuilds, Porsche 912, MGA1600, BMW2002, Chevy350, Landcruiser 6, Mercury 4 banger.

I asked Henry Schmit about the #8 sealant because I had the same concerns. Turns out that the sealant makes the O-ring reduntant. The sealant he suggests is ThreeBond 1208 which is a non-hardening sealant. (Threebond 1104 aka Yamabond is the sealant Henry, Porsche Motor Sports and Andial use for the case halves and cam carrier to heads.)

I smoothed this out before final assembly.

-Chris

[john walker's workshop]

i've always felt it was a good idea to apply a light smear of dirko in the #8 bore, just where the oring would touch. cheap insurance. nothing lke wishing you did that when you're looking at a 20 hour teardown when it leaks. but that's just me.

[ken martin]

John RULES!!!Dirko it is!!!

[snowman]

Theres another factor working in the mix here. I have had to assume the role of process engineer several times in my life. I have found that almost ALWAYS EVERYONE and I mean EVERYONE ALWAYS leaves out an important step when they talk about what they do. I have observed what is done vs what they said they do and almost without exception an important proceedure or step is omitted. Just a human kind of thing for unknown reasons. That makes it REALLY hard to compare what others are doing with what you are doing.

Until two people sit down and carefully document what is ACTUALLY done by a sucessful mechanic whose stuff dosen't leak, you will have unknowns lerking about, causing leaks. And even then Mr Murhpy pays you a visit.

[Jeff Alton]

Snowman, excellent point!!

Jeff

[stevepaa]

I am very hesitant to use a sealer material where an o-ring has been designed to be used. The o-ring needs to move under oil pressure to fully seal the path to the front of the case. Any material that hinders that movement may result in a leak. Any material that gets into the oil return passageway and hinders the return flow of oil may cause the oil to seek relief somewhere else.

It is sort of like knowing your weakest link and not compromising it.
Or finding the path of least resistance
Or yes, entropy does rule.

[stevepaa]

Jack,
Also there is the inherent use of shop aids that are not documented.
Yeah, I am a real stickler for procedures and documentation.

[adomakin]

surely a very light wipe of sealant can't hurt can it?

Andy

[stevepaa]

As this is my first 911, please take what I say with that understanding. However, having used o-rings extensively for sealing applications for contained high pressure combustion processes, and for sealing against modest pressures, 100 psig, during propellant casting, I know that you want them clean, without nicks of any sort, lightly lubed with o-ring lubricant, and the o-ring groove and sealing area clean. A nick, or foreign material will degrade the performance of the o-ring.

In the case above where the complete bearing area is covered with sealant, I would suggest that the o-ring function has been superceded by the sealant.

So I suspect, one either should rely on the lightly lubricated o-ring or go with full sealant usage. Anything in between may lead to a leak. Or not, depending upon the flow of oil, its pressure, the affect of the foreign material, etc.

This could also lead into a discussion of why "If a little is good, more is better" is very wrong in some cases, particularly o-rings.

[john walker's workshop]

suit yourself. you're correct about orings in general. then there's this one.

[Vonzipper]

John, I would have to agree about Dirko, I've been using it for years with great sucess. it's the only sealant that will stay plyable for years. as far as the case halfs and cam housings go it's 574 for me and curil K2 for cam boxes

[hessel]

I have been following the last couple of threads. I will be closing my case in a couple of weeks.

I guess if I combine all experiences here, I would come to the following combination of sealants:

Case bearing webs: 574
Case perimeter: Dirko
#8 bearing: Dirko or Curil T

By using this combination i'm still not sure in which order to tighten case, Perimeter first or Through bolts first?

For someone who's rebuilding his first engine it's hard to choose from all products out there. All your experiences & comments makes it even harder to make a decision.

Would appreciate your thoughts on the combination above and advise how to go about closing up the case by using these sealants.

Also, John, is there 1 type of Dirko from Elring? I need to order it and need to have the correct name and desciption for the product.

Thanks for all your help!!