The Complete Engine Sealant Thread...

[Jonny042]

Originally Posted by rdimarco

To glue or not to glue the main webs? Some pros say yes, other pros say no. I typically interpret this as both ways will work when done properly. Reducing shuffle by using loctite 574 on the webs seems like a benefit. I wanted to reassure myself that I wasn't significantly changing bearing clearances with the 574.
So instead of gluing my case together and measuring bores, I glued & bolted together two gauge blocks (advertised as flat within .0002"). Measurements of the stacked blocks with and without the 574 were the same (same technique each time), down to .0001" resolution of my micrometer. The loctite was applied to one surface as thin as possible, I spread it with a gloved finger and wiped off all excess until just the thinnest possible layer possible remained on the surface.
I am not a machinist or an engineer, so I can't say if this is significant. Even if the clearance increased by .0001", I would not be bothered by it on my personal engine. I have no way to assess sheer resistance when bolted together. After 18hr cure time and unbolting the blocks it took 10 moderate blows with a rubber mallet to separate them. A small amount of the 574 on the surface was still uncured liquid and could be wiped off, most of it needed solvent to remove. There was no visible excess around the edges.
My pseudo-science exercise may not be applicable, but maybe by sharing an expert will further educate me

That's really interesting - thanks for reporting that. Can you describe what sort of clamp load you placed it under?

[rdimarco]

That's really interesting - thanks for reporting that. Can you describe what sort of clamp load you placed it under?

I used a pair of 1-2-3 blocks. Four 5/16-18 grade 8 bolts in each corner, torqued to 24 ft-lbs dry.

[Inkblot]

@Rick- very cool- thanks for posting!

I've just gone through the process of sealing up my mag case, using Henry Schmidt's basic recipe. With some guidance from this forum, I decided (I mean, conceded...) that I had used too much sealant, so I tore it apart about 48 hours later. I took a bunch of pics- perhaps some of you will find it helpful to see what a relatively fresh over-sealant job looks like:

Originally Posted by Inkblot

Here are some more pics of the sealants, for the archives:












...and some looks at the 1211 around the #8 bearing:

Anyway, I know I'm double-posting here, so if you're interested, see the rest in my rebuild thread.

https://forums.pelicanparts.com/911-engine-rebuilding-forum/969543-newbie-73t-2-4-mfi-engine-rebuild-8.html


-Jake

[mikedsilva]

Thanks for posting this.

[bpu699]

Originally Posted by Inkblot

@Rick- very cool- thanks for posting!

I've just gone through the process of sealing up my mag case, using Henry Schmidt's basic recipe. With some guidance from this forum, I decided (I mean, conceded...) that I had used too much sealant, so I tore it apart about 48 hours later. I took a bunch of pics- perhaps some of you will find it helpful to see what a relatively fresh over-sealant job looks like:




Anyway, I know I'm double-posting here, so if you're interested, see the rest in my rebuild thread.

https://forums.pelicanparts.com/911-engine-rebuilding-forum/969543-newbie-73t-2-4-mfi-engine-rebuild-8.html


-Jake

Pictures 3, and 7, is what I always worried about...

In number 3 some of the sealant gets into the "u-channel" that drains that through case bolt... If that channel is blocked, the oil will seap through the bolt ends and on the ground...

In #7 there is an aweful lot of sealant around the hole that leads to the crank oil supply... what keeps that from flaking off and blocking the crank oil supply??? I know henry does it this way, and I used his sealing kit, but it still worries me...

[Tom_in_NH]

Originally Posted by dfink

If anyone cares 10 years now and hylomar is still keeping oil in the engine just fine.

Is there anyone else with experience with the Hylomar? I'm curious as I, at least initially, like the idea of non-hardening when it comes to oil galleys and such.

[fredmeister]

I saw a video on youtube of mechanics rebuilding an air cooled lycoming aircraft engine.

in it they used sealant like the 574 but also ran a thin silk thread along the case seam coupled with the sealant. claimed this acted like a barrier to oil trying to leak past the sealant only.

Any thoughts on this with the 911 case halves? same split case design as the lycoming so I wanted to start an educated engineering discussion on this.

Aircraft engines are more strictly monitored and less tolerant of leaks or other issues than automotive so is there merit to this for us air cooled rebuilders?

Thanks,
Fred

[ed mayo]

Did something similar once over 20 years ago on a customer 914-6 engine that defied usual rebuild efforts and would oily mist top of engine after hard running. Flat filed case perimeter then laid strip of dental floss around perimeter. Solved 98 % of problem, must have been okay, still together. Now you send case to Walt or Ollies and get perimeter planed and re line bore.

[Inkblot]

Originally Posted by rdimarco

I used a pair of 1-2-3 blocks. Four 5/16-18 grade 8 bolts in each corner, torqued to 24 ft-lbs dry.

Rick- I've read that fresh 574 can be applied right on top of old 574; that the fresh stuff will re-catalyse(?) the already hardened existing stuff. This would be really helpful to confirm... Any chance you could run your test again, this time applying more 574 to the already cured stuff between your test blocks?

Thanks!

Jake

[dannobee]

Originally Posted by Henry Schmidt

The 574 is applied to the main web to improve shear not as a sealant.
You might be surprised at how much 574 reduces main web shuffle.

I was just commenting on the discrepancies between the early and late manuals.

Even though "fretting" is common on the old mag cases, I doubt it makes much difference on an AL case. And much like boat tailing the mains, does shuffle pinning even do anything? Does it make more power? Does it increase the reliability? With the old mag cases, it did increase the probability of cracking, from what I've seen. But with an AL case, I doubt it does anything.

[mike sampsel]

So I used curil-T gasket sealer on my cylinder-to-engine-case gaskets (both sides) when I set my cylinders on during piston pin attachment hell (LOL). This was approximately 3 weeks ago.

Is the cutil-T is malleable enough? Or do not I need to reapply just before I place the head/cam tower assembly on and do the final torque?

[Henry Schmidt]

Originally Posted by mike sampsel

So I used curil-T gasket sealer on my cylinder-to-engine-case gaskets (both sides) when I set my cylinders on during piston pin attachment hell (LOL). This was approximately 3 weeks ago.

Is the cutil-T is malleable enough? Or do not I need to reapply just before I place the head/cam tower assembly on and do the final torque?

Curil T stays malleable almost indefinitely.

[Henry Schmidt]

Originally Posted by dannobee

I was just commenting on the discrepancies between the early and late manuals.

Even though "fretting" is common on the old mag cases, I doubt it makes much difference on an AL case. And much like boat tailing the mains, does shuffle pinning even do anything? Does it make more power? Does it increase the reliability? With the old mag cases, it did increase the probability of cracking, from what I've seen. But with an AL case, I doubt it does anything.

I guaranty that even late aluminum cases shuffle at the main webs. 574 helps prevent this movement, shuffle pins work even better.

[dannobee]

I'm not arguing about the "fretting" that one sometimes sees, I was arguing a different point. Does it make a difference on the dyno? Does it increase reliability? Which race engines did Porsche ever shuffle pin?

[Catorce]

Originally Posted by dannobee

I'm not arguing about the "fretting" that one sometimes sees, I was arguing a different point. Does it make a difference on the dyno? Does it increase reliability? Which race engines did Porsche ever shuffle pin?

I know this thread is about case sealant but it seems to have wandered into shuffle pinning. As the only guy in the world who actually makes a cast engine case and machines it in house, I have a Liam Neeson like "peculiar set of skills" that makes me uniquely qualified to comment on these issues.

1. Anything you put on the main webs, and I mean ANYTHING, affects the roundness and dimensions of the main bore. We line bore our cases with a $4000 line bore made by the Italian company D'Andrea. It is a boring head that is accurate to .0001 inches (1/10th). No, someone like Ollies does not have this. And they don't have the 300K CNC mill to run it either. What am I saying here? It takes accurate equipment to create a Porsche spec 3.6 bore of 65.000-65.019mm. Not a lot of room within that spec.

So starting with both case halves flat to less than 2/10ths, we then bolt the cases together and bore the main bore as well as the layshaft bore. But before we can consider any of this, the case mating surfaces must be PERFECTLY CLEAN. No dust, dirt or grime can be on the case halves, and certainly something like Loctite 574 would be thick enough to throw off the measurements.

If you think that all of it gets pushed out when you tighten the bolts, my question would be - then why use it? Clearly, the experiment with the 123 blocks shows that enough of it remains to influence the measurement.

On a micro level, you are creating an oblong bore whether you care to believe it or not.

2. Shuffle Pinning - Since most of my customers are engine builders I have heard every tale, story, and anecdote about shuffle pinning that exists. I believe or take stock of exactly none of them, and I just do what my customers ask. The overwhelming consensus has been to sleeve every through bolt with a bushing the same as the one found on the #1 bearing end. So 14 sleeves.

This does 2 things - 1) it prevents the case from moving obviously, and 2) it does what the Loctite is supposed to do: keep the oil in the through bolt bores inside the mains by acting as a bridge.

Therefore, we DO NOT recommend coating the main webs with ANYTHING because you already have shuffle pins on each hole and there will be no leaks due to the same shuffle bushings. Oh, and your bore is round.

Pic attached of ours.

Your mileage may vary.

[Cobalt]

I see your point on the shuffle bushing although I am curious why Porsche did not do this on their race engines. The factory sealed 996 cup engine we opened had used silicon sealant though-out along with on the webbing. Apparently they didn't see the issue at the time. Anyone have info on their more recent race engines?

Are you leaving the RMS surface as cast?

[Catorce]

Originally Posted by Cobalt

I see your point on the shuffle bushing although I am curious why Porsche did not do this on their race engines. The factory sealed 996 cup engine we opened had used silicon sealant though-out along with on the webbing. Apparently they didn't see the issue at the time. Anyone have info on their more recent race engines?
Are you leaving the RMS surface as cast?

Want to hear some heresy? I think Porsche didn't do it because IT DIDN'T NEED IT. And I still don't think it needs it, the cases are plenty strong. You have two sleeves at the #1 bearing and while they are only at one end, those sleeves have an incredibly tight tolerance.

We measured countless of those sleeves and found them to usually be within 3-4 10ths in OD. So they are precise. The bores they fit in are precise. So you aren't going to bet a bunch of movement.

We only shuffle pin like we do because literally two of the best engine builders in the country who bought many of our cases in advance told us to do it that way an I certainly wasn't about to question them.

I've built about 18-20 engines in my life by my count. These two combined do about 18-20 engines per YEAR. So I have nothing to add.

But I do believe the shuffle pinning is not necessary either in a stock case or especially mine.

As to RMS, old picture prior to machining which is done when case halves are mated. It's a machined surface.

They may have started putting sealant on the 996 Mezgers, but I have actually never split open a factory case and seen sealant on the webs of a stock air cooled car, maybe someone can comment here.

[dannobee]

Pulled apart quite a few in the day. Nope, no sealer on the "thrust blocks," aka main webbing. And none of the race engines had shuffle pins, either.

Don't forget the opposite side of the engine, the #8 bearing is a pretty stout locator, too.

[KTL]

I have a couple of questions about this location in the case halves.

1. I believe these main support surfaces are at the same depth/elevation as the case parting line? So wouldn't it make sense to provide sealant since the parting line is of course getting the sealant. In other words, you're keeping the surfaces same-same if you put sealant on both the parting line and the main supports.

2. I would beg to differ that there is some legitimate movement going on. Even on the later aluminum cases. I've seen both main support surfaces on my 3.0 case and my 3.2 case that have a roughened surface and others here have confirmed the same. I've been told it should be smooth like the parting line and thus that roughened condition is fretting from the two surfaces oh so slightly shuffling back and forth.

Is it catastrophic movement? I guess it doesn't appear so since the bearings don't show any problems. But why not arrest it if you can.

I have the through-bolt sleeves installed in my 3.0 case. cgarr did it for me. Unfortunately i've never run that case. Even if I did run it, I wouldn't be taking it apart any time soon so I could see the surfaces. I just figured it was a good thing to do since I noticed the fretting on the main support surfaces.

Here's how he does it on lowly factory cases. First make accurate plugs for the mains to hold it square bolted together and use a ½ inch reamer through the case through-bolt holes into the other case halve. This creates a ½ counter sunk bore to install the sleeve which is 1/2 inch OD 0.35 wall and 1 inch long. Then make sizing plugs for the case half that was reamed all the way through. This brings the through-bolt hole back to size. What this does is the case is used as a jig to line up everything. Works quite well. One thing people may not recognize is the 3 of the sleeves need to be notched out to allow oil passage for the piston squirters.

[Catorce]

Originally Posted by KTL

I have a couple of questions about this location in the case halves.

1. I believe these main support surfaces are at the same depth/elevation as the case parting line? So wouldn't it make sense to provide sealant since the parting line is of course getting the sealant. In other words, you're keeping the surfaces same-same if you put sealant on both the parting line and the main supports.

2. I would beg to differ that there is some legitimate movement going on. Even on the later aluminum cases. I've seen both main support surfaces on my 3.0 case and my 3.2 case that have a roughened surface and others here have confirmed the same. I've been told it should be smooth like the parting line and thus that roughened condition is fretting from the two surfaces oh so slightly shuffling back and forth.

Is it catastrophic movement? I guess it doesn't appear so since the bearings don't show any problems. But why not arrest it if you can.

I have the through-bolt sleeves installed in my 3.0 case. cgarr did it for me. Unfortunately i've never run that case. Even if I did run it, I wouldn't be taking it apart any time soon so I could see the surfaces. I just figured it was a good thing to do since I noticed the fretting on the main support surfaces.

Here's how he does it on lowly factory cases. First make accurate plugs for the mains to hold it square bolted together and use a ½ inch reamer through the case through-bolt holes into the other case halve. This creates a ½ counter sunk bore to install the sleeve which is 1/2 inch OD 0.35 wall and 1 inch long. Then make sizing plugs for the case half that was reamed all the way through. This brings the through-bolt hole back to size. What this does is the case is used as a jig to line up everything. Works quite well. One thing people may not recognize is the 3 of the sleeves need to be notched out to allow oil passage for the piston squirters.

YES, the mains are the same surface as the case parting line, but once the mains are clamped down together there is a degree of flex in the case parting line around the perimeter.

This is hinted at in the factory bolting order:

1. Bolt mains / case through bolts in star pattern
2. Bolt up case perimeter bolts.

Once you do #1 with zero gap, the case parting line is bolted together and with the sealant it will slightly flex open. Hard to believe, but the material does absolutely flex.

and good mention of not blocking the oil passages with the sleeves. We moved ours so that this isn't a factor.