Engine case question for you engine rebuilding mechanics

[Guest]

I am getting ready to put my C90-12F together.

Book talks about silk thread sealant for case half sealing.

Overhaul gasket set does not include or I have not found.

I recall using tite seal (I think?) last time.

But I am guessing that there are some better sealants like the black silicone gasket compound that I used on small 2 cycle engines.

So what are you guys that do a lot of engine rebuilds using for that?

Thanks, Dave.

[Hank Jarrett]

Re: Engine case question for you engine rebuilding mechanics

I laid a silk thread between the halves on my 65 and clamped the halves together. Never a single drop leaked at the case split. It works!

Hank

Make sure you route the thread correctly, especially around the bolts!

[Garry Crookham]

Re: Engine case question for you engine rebuilding mechanics

Dave,

Continental service letter SIL99-2C, available on Continental's website TCMLINK.COM, lists a Loctite sealant along with silk thread as the approved method. We (my employer) have received approval from the FAA to use a different sealant without the use of the silk thread and it has worked well for the last 15 years. The sealant is marketed under several different names, one being Yamabond 4.
We still use the silk thread method to assemble oil pumps, starter adapters, etc.
SIL99-2C shows the proper routing of the silk thread for your case.

Garry

[Guest]

Re: Engine case question for you engine rebuilding mechanics

Dave,

Continental service letter SIL99-2C, available on Continental's website TCMLINK.COM, lists a Loctite sealant along with silk thread as the approved method. We (my employer) have received approval from the FAA to use a different sealant without the use of the silk thread and it has worked well for the last 15 years. The sealant is marketed under several different names, one being Yamabond 4.
We still use the silk thread method to assemble oil pumps, starter adapters, etc.
SIL99-2C shows the proper routing of the silk thread for your case.

Garry

Garry,

Where do you get the silk thread?

Dave

[crispy critter]

Re: Engine case question for you engine rebuilding mechanics

The Loctite has actually been around many years. My dad had an old can from the 1950's. The Loctite is used to lay the silk thread into to hold it in place until the case halves are together. The Loctite will not expand as it dries like most sealers such as silicone, permetex, form-a-gasket, etc. Be careful using any of these previous mentioned because they can expand enough as they dry to change the main bearing clearances between the crankcase and the crankshaft main bearings which can lead to low oil pressures, poor oil flow, and reduced engine life.

[Ragwing nut]

Re: Engine case question for you engine rebuilding mechanics

Garry,

Where do you get the silk thread?

Dave

There is a Continental part number for it. Its been years since I bought any, one spool has lasted us forever.

[Guest]

Re: Engine case question for you engine rebuilding mechanics

Mike,

Want to sell enough for a C90? Trade for a wing tank placard? I need to get some, don't recall seeing any in the gasket set.

Dave

[Garry Crookham]

Re: Engine case question for you engine rebuilding mechanics

The Continental p/n for the thread is 641543. Any Continental parts dealer can get it for you, but it's expensive. There is a specific type of Loctite called out in the service bulletin. I would not use a can of unknown Loctite from the 50's as mentioned above.

Dave I sent you a PM.

Garry

[Edwin Otha]

Re: Engine case question for you engine rebuilding mechanics

I use Hylomar sealant and the thread can be found at a good sewing store. Some of the old manuals call it OO or OOO silk thread, I believe. What ever it was, they had no problem finding it. It's pretty thin thread.
EO

[N96337]

Re: Engine case question for you engine rebuilding mechanics

Dave,. We (my employer) have received approval from the FAA to use a different sealant without the use of the silk thread and it has worked well for the last 15 years. The sealant is marketed under several different names, one being Yamabond 4.

Garry

I'm trying to remember the trade name of the stuff I used on a Jacobs radial I did for a guy about 30 years ago, but I'm thinking it was pretty much the same as the Yamabond. It worked wonderful. BMW was using it on their air cooled engines at that time. The only problem was if you had to get it apart, as it really sealed well.
I think if I was going to build a Continental now, I'd really look at having LyCon do the O-ring on the mating surfaces. I saw that on a couple engines and it was very impressive!
John

[LostnSpace]

Re: Engine case question for you engine rebuilding mechanics

Mike,

Want to sell enough for a C90? Trade for a wing tank placard? I need to get some, don't recall seeing any in the gasket set.

Dave

Hi,Dave, I have some new Continental thread, lite weight wallet to prove it, I'll trade enough to do your engine plus a few feet for the two fuel tank placards, that I am on your list for, I too am about to put a C-90 together so I have the pattern for what is needed, gary

[Guest]

Re: Engine case question for you engine rebuilding mechanics

Hi,Dave, I have some new Continental thread, lite weight wallet to prove it, I'll trade enough to do your engine plus a few feet for the two fuel tank placards, that I am on your list for, I too am about to put a C-90 together so I have the pattern for what is needed, gary

Gary, thanks, I have a source for thread now and no longer need some. Gary are you using the old C90 cam/lifters or the new? The SB says replace it when cam needs to be replaced but mine came back yellow tagged ok so I am reusing. Will it make any real difference in engine performance?

Dave



Thanks to all for the info!

[Edwin Otha]

Re: Engine case question for you engine rebuilding mechanics

Pay close attention to the manual on the C90's. Some of the 24 degree cams used a little different hydraulic unit, the bleed down rate was slightly different.
EO

[Guest]

Re: Engine case question for you engine rebuilding mechanics

I know that the followers are different on the old cam ( don't recall how many degrees the old one was) but will check out the lifters. Thanks for the tip.

Dave

[LostnSpace]

Re: Engine case question for you engine rebuilding mechanics

Gary, thanks, I have a source for thread now and no longer need some. Gary are you using the old C90 cam/lifters or the new? The SB says replace it when cam needs to be replaced but mine came back yellow tagged ok so I am reusing. Will it make any real difference in engine performance?

Dave



Thanks to all for the info!

I found a NIB 35 degree overlap with the correct lifters also new from a gentleman who long, long ago built engines for the Cosmic Wind racers, gary