I have painted transom assemblies and trim tabs and getting ready to reassemble. When removing the stainless lines from the cylinders, there was some type of sealant in the threads. These are 3/16 tubing inverted flare, which the flare does the sealing for the fluid. My guess is the sealant is to try to protect the threads from salt/fresh-water getting into the threads between stainless and raw aluminum, causing corrosion.

Secondly, there are two studs on the transom housing that are not blind holes. These will also need sealer.

Anyone have a good recommendation?

Always used life seal. Holds and isn’t the end of the world to get apart when you need to.

What is Life Seal?

https://www.boatlife.com/product/lif...oz-tube-clear/

Either you guys are not on the same page, or I am lost? Thread sealant. I myself use the Permatex #3

I dont see a reason to use anything .. maybe anti seize?

Shah, Dan,

Stainless screws should never be installed into anything aluminum without SOME sort of barrier, be it a sealant, teflon tape, anti-seize, whatever. Time and the elements will almost guarantee a virtual fusion between the two, and salt water will definitely make it worse.

Thanks. Brad.

Maybe in theory but not in practice.
This weekend I replaced the trim lines on my transom assembly , stainless into aluminum distribution block. I bet those have been in there for 15+ years and had some salt water usage.Came out fine.

Dan,

Just forwarding established metallurgical knowledge. We all get away with flirt with disaster, so to speak, but the chemistry is proven.

I've had to throw away my fair share of model boat hardware (engine crankcases, for example) over the years where stainless screws had become one with the aluminum hardware they were tightened into, and almost had to HeliCoil the exhaust riser where the screw that holds my shifter bellcrank bracket mounts in our PQ after essentially ripping the threads out during my injector ordeal (probably should have, and definitely will if I ever pull the riser off for some reason). Neal Wallace of PQ Boats told me to not even try to remove the bolster seat frames from our boat (I had reason), as the mounting screws and aluminum inserts that are installed under the floor have almost assuredly permanently fused, and that I'll break more screws than I will remove. I have not taken the risk and dealt with a very inconvenient workaround for what I was trying to do.

Take it for what it is. Proceed as you will. I ain't telling anybody what to do with their boat, but I'll never install a stainless screw into an aluminum part without some sort of barrier. Hell, just a spooge of marine grease in the hole before installing the screw is some pretty cheap insurance that won't hurt a damned thing.

Thanks. Brad.

I`ve taken apart my fair share of stuff and the only thing that ever ****s me is fine thread, stainless on stainless. Stripped lots of bolts till I started sprayiing everything with WD40 before loosening/tightning.
Can`t say I`ve had your experience with anything I`ve disassembled .
Every drive , every transom assembly is stainless hardware /aluminum parts.