Sealing Case "Experiment" (so YOU don't have to!)
 

I suppose the best way to see how our various sealant methods for the case look "from the inside" would be to do an assembly with the sealant, and then let the case cure for a month - then take it apart again. Well, that is just what I did. More detail later, but here are the pics:

http://forums.pelicanparts.com/uploa...1157329616.jpg

http://forums.pelicanparts.com/uploa...1157329641.jpg

http://forums.pelicanparts.com/uploa...1157329667.jpg

http://forums.pelicanparts.com/uploa...1157329684.jpg

http://forums.pelicanparts.com/uploa...1157329707.jpg

http://forums.pelicanparts.com/uploa...1157329723.jpg

Only comment is on the 2nd picture from the top... The oil relief cut around the 2nd hole from the bottom on the left seems to be full of sealant. I always put sealer on the outer side of it to make sure it does not clog up. If the factory put it there, I would make sure it is clear. How critical is it? Comments from the pros? Lou

Yeah, that is one of my interesting little items I have questions about. The use of a sealant other than Loctite 574 on the case seems to bring with it the requirement to be very careful in certain areas. I now know a few of them from this test, and will point out what I can :)

More experienced hands than I are always great to hear from!

There is way too much sealant used on this case and in places it doesn't belong. It needs to be kept away from the oil relief areas and o-rings. There should be no sealant "inside" of the O-ring on the number 8 main bearing. You want oil inside of the O-ring to be able to get back into the case not be trapped trying to get out past the O-ring. Also there is sealant in areas that are oil galleries, this can break loose and clog up the engine.

Many more engines have been ruined by too much sealant than have leaked due to too little. All you need is a small bead around the perimeter or a thin coat of 574 if you use that. Keep it away from the oil galleries and relief areas.

-Andy

Sealant placement and type is exactly how we have been sealing 911 cases for 7 years. I see no areas of concern here, although I would not glue the oil cooler seals. Previously we used Loctite 574 exclusively and we were experiencing unsatisfactory results as did the Porsche factory around that same time frame.
After hearing that new, factory built engine were failing at a rate of 4% before they ever left the dyno (new parts, factory techniques), we decided that new techniques were required.

Gluing the #8 main bearing was something we resisted for the longest time. When we rebuilt a few engines (even aluminum cases) with #8 main bearing leaks, we started measuring the journal. We discovered that most #8 main bearing journals were not round. O-ring function best in round cylinders. We have seen journals that measure .015" out of round. Because most companies don't aline bore the #8 bearing journal, most #8 journal won't seal properly without glue.
Trust the o-ring if you like but we don't.

As for 574 clogging engine parts, I have never seen that. The sealant that is notorious for clogging oil passages is silicone. (RTV). 574 is anaerobic so it only hardens in the absents of air so it is soft until then.
We have never seen an engine damaged by too much 574.
I have seen some engine build with huge amounts (MM) and still seen no negative effect from it.

This engine was sealed using the methods that Henry suggests in terms of the sealant for each area. However, Henry was not involved with the engine sealing process, nor did I speak to him personally about any of the procedures. Instead, I started a thread to collect the "consensus" on the sealants used to try and find the best solution for me. See http://forums.pelicanparts.com/911-engine-rebuilding-forum/284737-complete-engine-sealant-thread.html

I have quite a few questions and observations from this process. The first was noted by len911 - what is that relief there for? I do not get the purpose...

Second (observation) - I seemed to be partially blocking the oil feed thru the forward studs around the #1 bearing. I will take more care in this area upon reassembly.

Third (observation) - I seemed to use a bit too much ThreeBond on the case perimeter. Less would have done just as good of a job.

The relief is there because the throughbolt holes are used as part of the oil distribution system and therefore under pressure. All the others are isolated so a bit of oil weeping simply dribbles harmlessly into the crankcase. A leak from this particular hole could find it's way to the outside of the engine if not for the relief.
regards,
Phil

The last engine I bought was a 3 litre that had been rebuilt with 574. The builder used too much and some of it went into the oil system clogging 3 cam spraybar holes. The resulting cam/rocker wear caused a poor running condition and made a good deal for me to buy and fix.

-Andy

Just so I'm clear.
Where would you put 574 so it would do what you are suggesting?
I assume it would have to be up stream of the spray bars.
I believe you but, I just can't figure out where.

I assume you mean upstream of the spraybars. The sealant was inside the spray bars and blocking the holes. I don't know the area that the 574 came from. The case had excess 574 in all the through bolt holes and in the pressure relief "ring" around the through bolt on top of number 7 bearing. The case also had some dried 574 in the bottom of the case. The case had 574 in the area where the pump o-rings are but don't know if any got inside the o-rings.

I'd say if the sealant gets into the through bolt holes it could get into the squirters too but that didn't seem to happen in the engine I bought.

-Andy

That is my point. If there was 574 in the spray bars, where did it come from ?

As for 574 clogging the oil squirters, I have never seen that either.

Sometimes theory doesn't match reality.

You edited out my comments on where the sealant was. My speculation is that the 574 in the oil galley's (through bolt holes and around the oil pump o-rings) made it's way downstream into the cam spray bars. The cam oil lines come from the number 8 bearing area of the case which is fed oil from the main galley that is connected to the through bolt holes, etc. I don't think it's much of a stretch to think that 574 in the oil galleys could make it to the cam spray bars. If you have other ideas of what caused the 574 in the spraybars I'm open to them.

-Andy

I was wondering about the curing time of the threebond. I smeared it on very thin (with my finger) and it seems to set really quick. It took me about 5 minutes between the last smear and bolting down the case. I have very little squeeze out and now am wondering if this is caused by the fact I only used a very thin coat, or because it already cured before torquing the case.

Very good thread. I recently discovered that number six cylinder spray bar hole(s) clogged starved my oil head for adequate oil. Did the rebuild on my engine 2 1/2 years ago. I am curious to see what will be found in spray bar.

Can the dried sealants we have been talking about break off from the edges of the surfaces where they are squished and travel through the oil circuit causing these types of failures?

It would seem the potential for this is very dependant on the sealant location. For example, outer case sealant would go thru the sump intake side of the oil pump, and make its way thru the oil filter - thus no issue. The sealant on the oil galley areas has more danger associated, but since we seem to have a consensus that Loctite 574 is used in these areas, the excess should not dry up and would be swept along as liquid during the engines initial operation.

That is my theory anyway :)

Chris,

I think that's part of the problem. The 574 stays liquid until it gets in an airless environment. Once you first start the engine the 574 can travel in the oil but it will harden at some point because it's surrounded by oil and will cure.

-Andy

I guess if it hardens in the filter, we don't care :)

Using the data offered by Loctite, I begin to wonder how 574 could clog a cam oiling tube.

574 does not form a breakaway bead. The break away bead is the portion of the glue that squeezes out and forms on the inside of the two joined parts. When hardened the 574 forms a bead that must be scraped off (you almost need a chisel). For those of us who have rebuilt engines that used 574 you know what I mean.

Next: If the product is not dry, when the engine is started the product will take at least 1 hour to cure at temperature. That means, any 574 that the oil system ingests will travel though the oiling system for at least hour hour before it can clog any oil hole. The engine oil should circulate through the oil filter at lease 20 times in that hour.

Final issue, according to Loctite, 574 will only hold pressurized fluid (read oil) in a gap of .010". It is rated @.020" for seepage but only .010" @ pressure.
Here the point, the oil spray bar holes are .034".
How can 574 seal a hole that size ?
Inquiring minds want to know?

Only the oil in the case bolt above the #7 main bearing is upstream of the cam feed line that feeds #1-3 cam housing. . #8 main bearing feeds the crank. All other case through bolts feed main bearings and squirters.

Not to turn this into a lovefest :rolleyes:, but it's this type of stuff that makes me defer to Henry. Sure there's lots of experienced opinions, but when my tiny brain gets twisted in a knot over minutia I breath a sigh of relief knowing I can follow his experience.:) (or maybe I'm just kissing his a$$ because I have boxes of parts on the way back to me :D ).

I didn't add my experience on here of clogged spraybars by sealant to get into a debate about how it can happen. I added the information so that others could avoid a problem that the engine I bought had.

I'll throw one last shot at an explaination. All the through bolt holes are upstream of the pulley end of the case. Any liquid sealant can run down the holes into the main galley when the engine is on it's side. The cam lines are the last stop in the oil system. The locktite goes through a hardening process just like any liquid that turns to a solid. During that time the viscosity increases. It's entirely possible that It could get stuck in a hole either while it's drying or after it dries if it breaks off of somewhere. The sealant that was in my spray bars was dark brown and looked like 574 but I don't know that it was for a fact. The clogs were "glued" and hard to remove idicating to me that the sealant was at least partially liquid when it clogged the holes.

I didn't imagine this problem. I'm not looking for anyone to agree or disagree with what happened or how. I'm only providing information that might or might not help other engine builders. Please use this information or not. I'm sure it's possible that it was some other substance that clogged my spraybars but the sealant seems to be the most likely based on what I saw and the amount of sealant that was in the case including the through bolt holes.

-Andy