#8 sealing one more time please
 

I have searched and searched but not found more than two pics of the threebond 1211 sealing a #8. Of course the pics were a little contradicting, and both claimed they used advice from Henry!! Chris posted a pic where he just "smeared" the 1211 in the bore where the #8 sits. I did see another pic where it was applied to just he oring area of the bearing itself.....

I have never used a sealer on the #8 (limited experience, by no means an expert) but after doing all the research feel I probably should. In fact, I bought the 1211 for just this purpose.

So how excactly should it be appled to the #8? Henry, you there?

Thanks

I really struggled with this!!! In the end, I made an "executive descision" and smeared an extremely light coat of 1211 (it's very thin) on the number 8 bearing saddle. I was careful to keep the the stuff out of the oil passage. I then added the dowel pin and carefully lowered the crank into place. I then smeared some more on the other case half bearing saddle. I'm still working on mine so I haven't had a chance to start it yet.

In addition I smeared the Three Bond 1104 (the product I used to seal the case) on the left case half (with out the perimiter studs). I though it would be easier to apply this way. I did not apply any sealant to the main bearing saddles.

I did find some threads on here on what options to take if there is a leak with number eight and you don't desire to split the case again...let's just hope I don't have to use that info!

#8 install
 

Jeff, I average 20- 30 911 engines a year and do not use a sealer for the o ring or the bearing OD, if you use the latest O ring and oil it it will seal fine, O rings by design need to be able to move in their respective grooves to do the job, if they are glued in place that wont happen. I have seen people silicone and glue just about everything in fear of leaks, if the seal areas are detailed properly and not damaged they dont need all that help, If you take a late (78 and later) engine apart for the first time you wont find that from the factory or an excessive amount of 574 on the case halves either.
Mike Bruns JBRacing.com

I've never used it either... ...but think about it every time as I dread the day that one leaks. My "special technique" is to make sure the o-ring has some oil or lube on it to make sure it goes intot he groove well and doesn't tear. Torn o-rings from assembly are the cause of every leak on these i have seen.

Hmmm, like I said, I have never had one leak either but....... Lots of folks swear by their methods too.....

grrrrrrrrrrrrrrrrrrrrrr, sometimes I wish I never look for answers to problems I haven't had! :) I know the factory doesn't use it, but man, I really don't want this one to leak...

Cheers

I got the same advise from Henry that Sand-man gave. "Light coat of 1211 on the bearing saddles." Sand-man I'm just getting ready to make the push on the cases and was thinking about the other bearing saddles. Every picture I see has sealant all over the joining surfaces. I've been wondering how the sealant does not enter the main bearings when the cases are joined. Even Wayne's book, on page 133 shows 574 on the saddles.

Time to make an "executive descision"! HAHA!

If you are planning to use sealant in this area (main bearing saddles) make sure to use a thin coat of 574. I think the 574 has a better chance of washing with/mixing with the oil and might be less likely to plug things up like a pure silicone product might. The key is THIN! As for me, it just didn't make any sense to do it. Also, my machinist Neil Harvey of Performance Developments said that he never uses sealant on the bearing saddles. If it leaks...it leaks back into the case. I had a fear of screwing up the bearing tolerances.

#8
 

Clearence issues are a concern, I have seen so much 574 on the saddles that you can razor it off and measure .006-.008 in. at the parting surface and that is probably a 1 to 1 added to the main brg. clearence. and with out sealant there and it leaks there no big deal but the clearences are what they measure when mocked up.
Mike Bruns

oh no, what have I started! :) What is the "new oring"? How is it different?

I too question the wisdom of sealing the main webs, but I have used only an extrememly thin layer of 574 there in the past, almost none. But like others have said, so what if it leaks back into the sealed case!

Time to decide, I want the bottom end together by the weekend...

Cheers

Jeff, Sorry to side-track the thread, but one more question. "I promise". Has anyone discovered the "great tool" for spreading the sealant around the case? I used to use those McDonald's stirs, but can't find'm anymore.

O RING
 

Jeff its just the green Viton O rings thats all
Mike

Just to stirr things up a little bit more: I believe that Hylomar Blue (NLA) is the perfect O-ring dressing. It acts as a lubricant and makes sure the O-ring can move. I prefer it to oiling the little buggers....

Ingo

Hi Jeff,

I did not use the "glue-it-all-up-and-it-won't-leak-method" but just made sure I was using the better O rings (Viton from Wrightwood), lubed up the O ring and I did put a very light coat of Curil-T on the outside of the bearing (outside of the O ring). It likely did nothing for the oil sealant but I like the green color ;-)

I found the Viton seal appeared to be a bit fatter than the stock one so I figured that it would seal better...but the engine does not have much mileage yet so time will tell.

Oh, I did use 574 on the saddles since it had a high squeeze out and the 993 manual does say to seal the saddles and the threebond product on the case perimeter. It all looks like it works fine.

Best of luck!

Cheers,

Mike

I was told bt a reputable engine builder here in CT that sealant on the bearing saddles was a no-no. No reason to seal those surfaces and introduce the rick of screwing up the bearing fits.

No problem at the nose bearing end, as the nose bearing itself seems to offer protection, but what about the other end? You're going to half to seal that one, as it's the perimiter. Time to have a beer, this is getting too deep!

Seal along the perimeter but not on the internal saddles.

Thanks Tom. That's pretty much what I had in mind.