John,

I am preparing to seal up my case tomorrow. However, after reading this thread I am having second thoughts.

1) I was unaware of the opinions regarding the use of 3 different sealants (4 if you count Curil-T). I am sold on the idea. Hopefully I can find these other sealants locally.

2) The picture of your case is ridiculous (in a good way). I can't believe how clean it is. It looks fresh from the factory. After having mine cleaned at a local machine shop, I spent 30-40 additional hours hand cleaning. I was comfortable with my work until I saw your picture :(.

Thanks for the great diagram and thanks to everyone else who shared in this thread.

Oh, and I am now worried about those blue through bolt o-rings. They don't seem to have a very good reputation!

Cheers,
Craig

There's a Dow sealant for O-rings, Henry Schmidt offers it for sale, along with the others noted here. Also, Viton (green) versions of these are the ones to use.

Very timely for this thread to be bumped to the top. I can add my recent experience:

-On my recent 2.7 build, I used Henry's Threebond x2/Loctite 574/Curil T method. This really worked out well, I am very pleased with the results. In the course of planning the build, I've talked to a few pro builders who really like the Threebond as a case seam sealant as well. Good enough for me. Having said that, my engine assembled with 574 is pretty dry.

-This time around, I did NOT use Curil T on the crank snout or flywheel seals. So far, both are dry. They were much easier to install WITHOUT the Curil T. When using the Curil, the seals very effectively walk themselves out of their seated positions unless I pin them down overnight. Maybe I have been using too much of it? Dunno, but I'm done with it on crank seals. I did use the Curil T on my cylinder base gaskets, breather gasket, cam thrust plate gaskets & o-rings, etc. I think that's about it.

MCA/Craig - if you've got the sealants you need and want to proceed with your build, here's a tip. Assemble the bottom end without ANY through-bolt o-rings. If you're assembling alone, this really helps you to get the case together quickly. When you're happy with the completed bottom end assembly, you can then remove your through-bolts and install the o-rings - one at a time. Remove bolt, install o-rings, reinstall bolt, torque to spec, then move on to the next bolt, and so forth (in the torque sequence, if you're really being anal - I do/am), until all o-rings are installed.

It is easier to get confused about what bolts have been ringed and which haven't this way. Not only do I pre-count my o-rings twice to make sure I start with the right number, but I also mark each acorn nut with an 'X' using a Sharpie after installing the o-rings and re-torquing. If all the nuts have 'X's and I am out of o-rings, then I think I'm in good shape :). Having done several builds with both the blue and green o-rings, I would say hold out for the green ones, no question. They really fit much better. I don't think I've ever had a green one 'squeeze out' from under the washer like I almost always had with the blue ones.

Great idea. Once I get all of the through bolts torqued, can I immediately go back and include the o-rings or do I need to wait a period of time to allow the case sealant to set?

I plan on moving forward with the blue o-rings for the through bolts. Actually, I have two sets of the blue rings (ordered too many by mistake) and the set that came inside the gasket kit seem to be WAY cheaper than the darker blue rings that came in a separate baggie. In fact, I was quite surprised to see that one of the rings in the gasket kit was torn.

Maybe the darker blue rings are stronger? Not sure. Anyhow, I suppose that I can go with the green rings if I start having problems.

Thanks,
Craig

One builder suggested using black Permatex silicon on the thru bolt blue seals. Any thoughts?

In my next most perfect life somebody is going to put a chart together grouping all these products keyed to Waynes bible.

Craig - Will you be applying any sealant (574?) to the main bearing webs? If so, give this an hour to set. If not, any work you do on the main bearing hardware should not have any impact on the case perimeter/seam, especially if you only loosen and re-torque one bolt at a time.

Old Tee - try a search here on the engine forum, this one has indeed been debated hotly. I'm strongly against it...I did try it but did not like it one bit.

Having just followed dtw on a 2.7 rebuild I have a little advice too. I would not bother putting the crank seal (flywheel side) in until the case is together. I put Curil T on the seal as I put the case together and it walked out. PIA. Another thing I did that I won't do again is put the assembly lube on the crank bearing before I rolled the sealer on. I will put the case sealer on first, then I would put the assembley lube on the bearings, and I would use only a little, I put way too much on. When you drop the crank in the lube will squeeze out and get on the case sealer at that joint. Not good. I would skip the silicon on the case bolts, I did. I did not want any silicone floating around inside the case. I put the case together without the orings on the case through bolts and then took them out one at a time and then put the orings on and then torqued them. Make sure you hold the bolts when you torque the nuts, if the bolts turn you can tear the orings.
One more thing I did which goes against everything the engine builders suggest is that I put the nose bearing in without sealer, I just put some lube on the oring. I did not have any leaks there. Mine was not leaking when I took it apart, my case did not need to be align bored so I left it like the factory put it together.
Ray

Curil T is on the no-no list for the seals, for the exact reason Ray states.

Dow 55 is a specific sealant/lube for O-rings. Why not go with current chemical technology here. Blue o-rings are the crappy ones....green are Viton, and are the ones you should be using for their superior strength.

Putting lube on the bearings AFTER the sealant goes on does not seem like a good idea to me, with my total of 1 rebuilds. How much lube are you putting on? Everything n moderation. You're on the clock when the sealant goes on, and I cannot imagine blowing X amount of time screwing around with bearing lube after-the-fact. You run a bigger risk of slopping lube on the sealant, IMO.

Well, I ran out of time today and couldn't get the case together. I spent the day cleaning and organizing my bags of seals / bolts / nuts / washers.

Thanks for the tip regarding the through bolts. In all likelihood I will stick with the 574 unless I can get my hands on the other stuff before Friday.

I ran into the problem of the roller picking the lube off the bearings as I was rolling the 574 on. As far as being on the clock goes, the 574 does not start to cure until there is no air around it, or in other words until the case halves go together. You can put some 574 on a surface and leave it exposed to the air and the next day it will still be pliable. Anyway it is a matter of technique and whatever way you choose to put the stuff on. And yes I used plenty of assembly lube. Too much for sure. But next time I will roll the case, then lube the bearings. If you skip putting the orings on the through bolts before you torque them you have a lot more time anyway. I just went back and took them apart one at a time and then put the orings on and retorqued. When I sealed my case the whole thing was torqued up about 30 minutes after the case halves went together. As far as the sealant went, I put a very light coating of the 574.
Ray

When you guys say "rolled on" when referring to the sealant application ... what does that mean exactly?

The factory manual calls for rolling the sealer on with a short nap roller if I recall. I just went to Wally World and they carry a small roller and tray with foam rollers and nap rollers and a handle, the rollers are about 4 or 5 inches wide. The whole thing is like 7 bucks. I used the foam roller. I would not use their cheap nap rollers you might wind up with fuzz in your sealer. Anway I used the tray like a paint tray, loaded the roller with sealer. Then used the roller on the case to spread the sealer. I did not use much sealer and the roller put it on nice and even.

Are you rolling sealant on the left case half or on the right case half? (I think you have to apply to the right half if using 574).

If you are rolling on the right case half (side mounted to stand) are you doing it before installing the crank, pump, and intermediate shaft?

Seems like it would be tough to get a roller in those tight spaces with the case internals installed.

Of course, you roll it on the half without studs sticking out of it. Just like the factory did.

I wonder why Wayne's rebuild book says to spread it on the right side? On page 133 it shows a picture with the sealant applied - side mounted to engine stand with studs in it.

Is there are reason he specifies it this way?

Also, how do you know how the factory did it? (not being a jerk - just curious)

Ok, I admit it, I rolled the side without the studs! I even used 574. I should be ashamed of myself. Seriously. I have no idea what difference it makes. But you will still have to use a brush to get sealer into the tight spots. I don't have any case leaks either. I get one drop of oil off my sump plate, but I only got one gasket in my gasket kit, so I had to use one old one. I have new ones on order.

I started a thread about the 'sealant on which case half' question two months ago. The discussion:

http://forums.pelicanparts.com/911-engine-rebuilding-forum/408468-why-dont-more-us-put-adhesive-upper-case-half.html

If all you're using is 574, then the clock thing isn't as significant. But, I still think 574 would be altered if left exposed to the air. Some of the liquid has to evaporate, thereby making it's squeeze properties different, and MAYBE, not as consistent/effective.

But, I used Henry's recommendation of 4 sealants, so I had some other stuff to concern myself with besides 574 only. I never had any issue of getting lube in my 574, or vice-versa.

Would someone tell me why it is necessary to add any sealant to the main bearing caps/ saddles? What purpose does this do? If you measure your clearances, would this not add to the clearance? If not, then what purpose does it achieve? If it leaked, where would it leak to?

On Neil's (Performance Developments) advice, I did NOT add any sealant to this area. Over 13,000 daily driven miles since my rebuild and no issues to report with the case leaking.

EDIT: the only area that has developed a tiny weep of oil (not even dripping yet, but it won't be long) are the chain covers. I used a thin coat of 574 on the gaskets. I have purchased new gaskets and will either use a coat of Hylomar or Curil-T on them and button it back up.