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No silk thread method?

B

bob turner

Registered User
Saw this mentioned on another thread (no pun).

I have been assembling small Continental engines with no thread for about a half century - not lots, but enough to keep me flying. I originally used Rolls Royce Hylomar, which is no longer a good choice (Loctite makes an orange equivalent). I have never had any problems.

Local shop is getting ready to assemble a C-90. I would recommend no thread based on my own experience, but that is a lousy way to back up such a recommendation.

Are major shops moving away from the silk thread method of case assembly? Or am I making a mistake?
 
I would reference TCM SIL99-2C or latest revision. I haven't seen a published procedure on a Continental that doesn't use silk thread, Lycoming has a published method.
 
How about Anaerobic gasket maker. I've heard that the car manufactures are using it on the new engines. I've used it a bit on cars and tractors. Very easy to use. It doesn't start to seal until the parts are put together (no air).
 
I know most are tired of hearing it, but how about doing it the way the manual says? If it says sealant, use THAT sealant. If it says use silk thread, use silk thread. If it says no sealant, don't put it on.

Crankcase halves are critical in that if damaged, you'll have no engine. But it's also critical in that if assembled and found to be leaking (or assembled incorrectly) you'll need to remove the engine from the aircraft and then disassemble it completely to fix.

Just follow the manual.

Web
 
DUSTERMAN said:
How about Anaerobic gasket maker. I've heard that the car manufactures are using it on the new engines. I've used it a bit on cars and tractors. Very easy to use. It doesn't start to seal until the parts are put together (no air).
Click to expand...
Might be fine with an EX engine but nothing you want to use in a Certified build.
One thing Lycoming noted about non approved sealants is people select a sealant like you mention, but that sealant was never approved to be used between critical machined surfaces. Most of those sealants are designed for timing case covers and oil sumps essentially engineered as a gasket replacement.
In those applications, even after torquing the fasteners the sealant has a measurable thickness. It then is prone to a slow creep out of the joint.
Two issues here, the slight thickness imposed by the sealant reduces bearing shell crush right from assembly.
Second the chance of slow creeping my result in loss of torque on through fasteners. Nether is a good thing.

There are sealants that could be considered safe such as those used on case halves of motorcycle engines as well as outboard motors. But I would truly not go there on a Certified engine and make sure you truly understand the sealant's properties.

The recommended and approved Locktite 515 is derived from that family of sealants.
 
DUSTERMAN said:
How about Anaerobic gasket maker. I've heard that the car manufactures are using it on the new engines. I've used it a bit on cars and tractors. Very easy to use. It doesn't start to seal until the parts are put together (no air).
Click to expand...

Thats what I used on the last 2, one 14 years ago and over 1200 hrs. No leaks anywhere

Glenn
 
Ask Frank Sparandeo "Miss Pearl" about using some alternative sealant and what happened to the engine on his Pacer.
 
Silk thread is a great product for the application. I don't understand why anyone would resist using what's worked for 80 years. Sealants are better, sure, so why not use both?
 
You guys are ruff. I've had wolves pee on my tie down ropes but never a two legger that lived to talk about it.

Gary
 
Steve Pierce said:
I'd pee on his tie down ropes myself. Legend in his own mind. ;)
Click to expand...
Had a roommate in college that would borrow money then conveniently forget to pay you back. If asked about it he would shrug his shoulders and tell you next week. Instead of getting mad, we’d move his bed, pee on the carpet then move the bed back. This happened “several” times over a year. He never could figure out where the smell was coming from. This turned out to be the ultimate in anger relief.
......Oh, by the way, his room was the only one that didn’t have a window that would open:p
 
stewartb said:
Apparently there's a competition for top idiot. It used to be an interesting topic.
Click to expand...
No one said you had to read every post. If all you were wanting was technical information you should have stopped at the sealant PDFs. Sorry about the kids playing on your yard. Build a taller fence or buy a bigger dog.
 
bob turner said:
Saw this mentioned on another thread (no pun).

I have been assembling small Continental engines with no thread for about a half century - not lots, but enough to keep me flying. I originally used Rolls Royce Hylomar, which is no longer a good choice (Loctite makes an orange equivalent). I have never had any problems.

Local shop is getting ready to assemble a C-90. I would recommend no thread based on my own experience, but that is a lousy way to back up such a recommendation.

Are major shops moving away from the silk thread method of case assembly? Or am I making a mistake?
Click to expand...

Why is Hylomar no longer a good choice?
 
The topic tripped a trigger Stewart, Frank had his engine start coming apart from using silicone on the cylinder bases, he is a DER/A&P/IA and self proclaimed expert but the coup de grace was when as the president of the Short Wing Piper he sued SJ and I over using the name Short Wing on our website. These threads are kinda like bullshit sessions in person you just don't get to hear the laughter and the different accents.
 
You should start a Frank thread and post his adventure adjusting the ailerons on his Pacer
 
bob turner said:
….I have been assembling small Continental engines with no thread for about a half century - not lots, but enough to keep me flying. I originally used Rolls Royce Hylomar, which is no longer a good choice (Loctite makes an orange equivalent). ….
Click to expand...

Please elaborate on the hylomar comment.
 
Okay. My first tube was in 1966. $35. That was almost half of my monthly paycheck (military).

Loctite started making it about 20 years ago - $2.50/tube.

Two or so years ago I tried to buy another tube (stuff lasts a long time). $11 bucks, but not the same stuff, and not Loctite. It came out of the tube like cottage cheese.

So I contacted Loctite. Had a nice phone conversation with an engineer. They had some kind of licensing problem (odd, I guess, because patents run out after a max of 20 years, so it may be a “branding” problem).

i suspect they kept the formula, and changed the name (I can get it) and the color (blue to orange).

In any case, my understanding was that Rolls Royce had approval to do away with the silk thread. Been a very long time, and I cannot prove it. I would love to know how the silk thread prevents fretting.
 
Correction - not Loctite. Permatex “Permashield” 85420. And it was via e-mail:

We sold Hylomar thru Permatex back in the 90’s but they pulled the plug from us. We have an item called Permashield which is a substitute but has not been tested or approved for aviation use. I do know that Hylomar is still around because I saw them at an engine expo in Chicago in 2017. They seem to have even more products than before.
 
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