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A couple of engine assembly questions

cguarino

Well Known Member
I'm finally about to reassemble my engine after a main bearing failure. I've read the service instructions but I want some advice from guys that do this regularly. My first question is what do you use to pre-lube the cam and lifters and the bearings when assembling the engine? Lycoming recommends lubricants that are near impossible to find. My second question is about the case sealant. Lycoming has approved 3 methods. Perfect Seal #4 and silk thread, Loctite 515 and RTV 102. Which one works the best? Thanks in advance for the help.
 
Amazon, Aircraft Spruce, and Ebay are your friends in finding unusual lubricants. I don't remember any particular difficulties finding the Lycoming specified ones when I did my engine.

On the case, I used locktite without the silk thread, which has worked fine. I can't tell you if the other choices are better or worse. At that point, it is probably down to the skill or attention to detail of the assembler and the condition of the case halves rather than the specific sealant used.
 
For cam lubrication I used US Lubricants Assembly Lube (one tube is plenty).. But you should be able to find Lubri-bond A (skygeek seems to sell, though in spray can??)... I'd stick to something that comes in a tube.. but that's just me :)

As mentioned, you should be able to source out everything fairly easily.. even that food-grade anti seize .. .need a small dab of it... you'll never use 99.999% of the can content again ..
 
Lubes & Sealants

Aircraft Specialty Services in Tulsa supplies a little tube of cam assembly lube with their camshafts. I presume they would sell it outright. They should also be able to supply the silk thread. On the recommendation of one of the well known engine shops I've used Hylomar Aerograde (blue) sealant with the silk thread on several engines and have had great results.

Don Broussard A&P, IA

RV-9 Rebuild in Progress
Piper Pacer
 
You can buy moly cam assembly lube at any auto parts store, there's nothing special about it, here's a NAPA p/n
SEP 55403B
Tim Andres
 
You can buy moly cam assembly lube at any auto parts store, there's nothing special about it, here's a NAPA p/n
SEP 55403B
Tim Andres

And the Vantage Overhaul Manual simply calls out for "cam pre-lube" and states a "moly-graphite" one is preferred.

Just go to an auto parts store as Tim says...:)
 
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