Where to apply sealant

[tom1394racing]

Henry

Thanks for you input...learn something new every day here.

[cmcfaul]

I can't find Loctite 574 anywhere. Looked at the local stores and online. Anything else work as well.

Chris

[roy gray]

dirko,dirko,dirko.superior silocone.loctite and all permatex's are similar to t.rex,as are most people who use them.i.m.c.sells dirko.

[Henry Schmidt]

Originally Posted by roy gray

dirko,dirko,dirko.superior silocone..yada, yada, yada.........

Elring Dirko is an RTV Silicone. As such there are very limited uses on a 911 engine.
This was used extensively back in the 70s by type 1 VW engine builders then abandoned as more efficient products became available. It works pretty well for sealing the water pump on a Chevy V8.

Most Porsche engine builders find RTV Silicones inappropriate for assembling air cooled 911 engines.

[lindy 911]

Chris,

574 and all the other sealants are available here at Pelican and from Supertec.

Lindy

[cmcfaul]

Thanks, Just placed on order with Pelican for the Loctite 574 and the Curil T.

Chris
73 911 E

[cpetommy]

What is the best way to apply 574, between the cam tower and cylinder heads, with a small paint roller?

Tommy

[Walt Fricke]

The books all say a small paint roller, and show you what to cover - the whole of the milled flat carrier surface. And that works.

But I just squeeze out a thin line on the carrier around the port openings, with loops around all the stud holes. Works fine, as it squeezes out to cover a larger area. And in the area between intake and exhaust you don't need any, because nothing is going on there, so it is a waste of Loctite.

Walt

[winders]

Originally Posted by tom1394racing

Why would it be necessary to put any sealant on the bearing saddles?

These is no leakage path and the sealant should not stabilize the saddles.

I have been told it should not be done.

I just saw a post by Trevor Dawe (Peter Dawe's son) on Facebook about this. He says main webs should be clean and dry. William Knight says the same thing. When a case in line bored, is any sealant on the main webs? I don't think so. So why would you put sealant there when assembling an engine? All it can do is mess up clearances.

[reclino]

I bought head studs, rocker arms and a sealant kit from Henry, and believe he is a top notch builder, and he is qualified to put sealant on the case webs at the main bearing locations.
I also consoled with Peter Dawe, and had my case, and rotating assembly checked by the machinist he uses. All bearing clearances were checked with the case assembled dry, and I was told all NOT to put anything on the case halves at the main webs. He said if your an expert like Henry, fast, and do it perfectly you might only add a few tenths (.0001"). I am not that expert, and I will assemble the webs dry, just like the factory did. Just like any precision bolted assembly that gets measured dry. I hope to put this engine together one time.
Sealant on the webs can and does go wrong, leading to oil pressure problems.
David

[Henry Schmidt]

.0002-.0003 of an inch is the expected crush on 574 when properly used.
Properly applied and assembled is the key phrase. Timing is everything. If you are not confident in your assembly technique avoid using 574 on the webs.

Originally Posted by Henry Schmidt

I have articulated and documented the theory of shear resistance offered by LocTite 574 flange sealant. I have illustrated in previous posts the movement called shuffle that occurs where the case halves come together at the main webs. There is absolutely no down side to properly applying Loctite to the main webs.
The choice is yours.

One additional thought: Shuffle is a real issue in a high performance Porsche engine that can be best addressed by methods like shuffle pins or hollow dowels. That said, anything that can add to the stability of the engine platform is a good thing and we have first hand experience that gluing the webs reduces shuffle.

Shear strength of 574 is well documented. Reducing main web shuffle, especially in mag case motors is valuable. I have seen zero documentation [claims of detrimental effects] of stabilizing main web contact. The theory that it "may" cause significant tolerance issues is just that, an undocumented theory.

[Henry Schmidt]

Here's a homework assignment for those of you who prefer research over experience.
Look up the tolerance for main bearings bores. Then look up the crank main journal tolerances. Then take into account bearing fluctuations.
Given the factory prescribed tolerances, do any of you believe that Peter Dawe, William Knight or Hans Mezger himself would be concerned with a tolerance variance of two to three ten thousands?
Many race engine builders, Porsche and otherwise are recommending and building engines with over .001" additional main bearing clearance over the Porsche prescribed numbers. .0003" really?

[Henry Schmidt]

Reviving an eleven year old thread....

[reclino]

Henry, as I said I think it's possible to do it correctly so that the bore only gets bigger by a few tenths. But yes, Peter and machinist Nick told me not to do it, and they had torn down fresh rebuilds where there customer's had followed your advice and way too much cured sealant on the webs, then had oil pressure issues. Maybe it was outdated Loctite curing too fast, but for me it's not worth the risk or stress of wondering if I did the assembly fast enough.....
Of course nothing about my rebuild is happening fast.
David
Plodding along
But enjoying every minute of it.

[Henry Schmidt]

Originally Posted by reclino

Henry, as I said I think it's possible to do it correctly so that the bore only gets bigger by a few tenths. But yes, Peter and machinist Nick told me not to do it, and they had torn down fresh rebuilds where there customer's had followed your advice and way too much cured sealant on the webs, then had oil pressure issues. Maybe it was outdated Loctite curing too fast, but for me it's not worth the risk or stress of wondering if I did the assembly fast enough.....
Of course nothing about my rebuild is happening fast.
David
Plodding along
But enjoying every minute of it.

No worries. As the engine builder, you are responsible for assessing your best route to success.
As a successful engine builder, it my pleasure to share our methods for success.

[Classic11]

Is Threebond 1194 now 1184?

[Neil Harvey]

The wonderful thing about building engines I have found over the years is, nothing is an absolute nor is it the only way. What works for some may not work for others. And that's what makes it great. We learn something from others.

I personally would not add anything to the main webs. Solving the fretting should be done in other ways. But if it works by adding sealant there, who's to say "don't do it".

If you sleep better at night by doing it and your engine runs just fine, then what's the problem.

We all have our own quirks, do's and don'ts and engine builders are full of them. I'm over flowing with them. I hate when air cooled cylinders are call "jugs". You put milk in jugs. Never use an engine as a tool bench. That's what benches and tool boxes are for. I could write a book.

[Henry Schmidt]

Originally Posted by Classic11

Is Threebond 1194 now 1184?

Yes

[TimT]

Reviving an eleven year old thread....

Yes I noticed that... someone apparently is trying so hard to be "right" and win the internet..

Not sure what cred being a checkbook mechanic gives..

[winders]

Originally Posted by TimT

Yes I noticed that... someone apparently is trying so hard to be "right" and win the internet..

Not sure what cred being a checkbook mechanic gives..

Yeah, sure....

Actually, I read this thread a while ago when I was doing research on sealant used on engine cases, heads, cam towers, etc. Why? I had to pull the heads off of my race engine to get them R&R'd as I bent some valves on a missed shift. I took the heads off and I was going to be putting them back on. In the end, William Knight flew out and we reassembled the engine together. I could have done it myself but I am glad he was there to show me how he did it.

Anyway, I was puzzled as to why you would want to use sealant on the main webs as they don't need to be sealed and the roundness of case bore would be affected by the sealant. I had seen several Factory engines taken apart and with no sealant used on the main webs. I was pretty sure I saw an Andial engine being put together with no 574 on the main webs either.

Fast forward to yesterday and I saw a post on Facebook showing a case with 574 that was .0035" thick. The post admonished people to leave the the main webs "clean and dry".

That reminded me of what I read in this thread. So there you go. Maybe someone that knows what they are doing can get the 574 applied thinly enough and the case torqued tight before the 574 cures too much. But clearly this did not happen in the Facebook example.