Thread Sealer for Underwater
 

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?

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.

You have been lucky, learned this lesson 37 years ago on my DUCATI, and it had not seen a salted northern Indiana or Michigan road yet.

And as you have found Stainless to stainless will gall real quick as well.

Dan,

It may very well come down to the alloy of the stainless and that of the aluminum. "Stainless" is not "stainless". 18-8 is considerably harder than 316 (the two most common alloys used for screws/bolts), and is undoubtedly less likely to gall against another softer metal. Same for aluminum, especially in the casting sector. If these aluminum parts we are talking about were made from 7075, it probably wouldn't be an issue at all, but that would make them WAY more expensive.

I'm also very certain the cathode system is lending a hand, but normal environmental corrosion of oxidizable metals is not the same as dissimilar metal electrolysis.

It's just not worth the risk to me, given the gravity of the potential risk. When Neal Wallace told me what he told me, the scenario ran through my mind of what would be involved in recovering from the mistake of snapping off a fused screw in an aluminum insert glassed into the bottom of the floor of our boat. Ick. Gives me shivers. But, had they had the presence of mind to install them with a barrier, it wouldn't have been a problem.

I'm glad you've had the luck you've had with it. I'm not that lucky.

Thanks. Brad.

Ha! You are right. I was thinking more of the 2 threaded pieces on the k planes that have nuts on them and where the hoses thread into.

I only use the basic permatex pipe dope on pipe thread. Inverted flare doesn’t need it.

I have taken somewhere around 20 top caps off older merc alpha 1 outdrives. They use stainless hardware in the aluminum housing and I have never seen any sort of sealant/lubricant on them. Out of those 20 outdrives (4 bolts each) I have broke 2 stainless bolts trying to get them out and had to replace the housing on both those drives as I could not get the broken bolt out. Tried everything in the book other than drilling/tapping and they would not budge. Was easier to throw in the scrap bin and start with a new one.

Ryan,

HEY! :readinghelp:

It wouldn't be that hard to build a drill bushing fixture that would allow for the drilling out of those broken bolts and then installing HeliCoils. Assuming you only had one bolt broken off, the fixture could be bolted in place through the remaining three, and a drill bushing installed in the fourth location, then drill out the bolt and thread for the HeliCoil.

How many different top caps are there? I'm honestly seeing a market opportunity here for someone with the wherewithal to MFR such a kit. If I were a marine service shop, especially in a coastal area, I'd definitely have one on the shelf. It would pay for itself with just one broken bolt and scrapped drive casing. This is right in my wheelhouse. Anybody got a top cap or two they aren't using I could get dimensions from?

Thanks. Brad.

1. Drilling through stainless sucks, let alone at least 1" thick

2. The top cap I'm assuming is high tolerance based on the fact it has a race pressed in for an upper gear bearing. Would not want a helicoil drilled via a jig if that's the case.

3. Alpha 1's are a dime a dozen. I end up with them for free after parting a boat out, and at any given time have at least 2-3 on hand.

4. Drilling through stainless SUCKS

Ryan,

Keep in mind that this is what I do. Not outdrives. Machining. Tooling, in specific. This is my wheelhouse.

1) With the right drill, not really. Split point cobalt drills make short work of it and are readily available. Additionally, left-handed drills are available, and they will very often catch the threaded slug and back it out long before actually turning it all into chips.

2) Even better. That means the jig can be doweled just like the top cap is, ensuring the HeliCoil is on location. Are these top caps doweled or do they have alignment bushings in the tapped/clearance holes? I'm hoping you're not thinking I would suggest using the top cap as the jig....

3) Bravos? Not to mention... Which is cheaper? Drilling and tapping for a HeliCoil or gutting an outdrive to install the parts into a free case? I suppose this would hinge on why the top cap was coming off, but I'm going on the assumption that it is often just for a bearing replacement or general service, and not always a total rebuild.

4) Again, not really. Drilling stainless, and far worse, just means that it's a day that ends in "Y" for me.

At the end of the day, I'm just thinking out loud. A large part of my day is spent solving someone's problems. Henry Ford didn't even try to invent a faster horse, which is what the majority of people wanted.

Thanks. Brad.

There is no dowels or alignment bushings used. The bore of the housing is used with a step in the top cap. I could potentially see a market for bravo drives, but typically a boat owner with bravos takes better care of there boat than an alpha owner. I have yet to break a bolt of an alpha that was in good condition and not neglected. And yes, with the right tools stainless can be drilled fairly easy. I do not own these tools, and at this time do not see the ROI in purchasing them. All my stainless machining I prefer to use my local machine shop

Ayuh,..... By far, the best sealant for that issue is Quicksilver Perfect Seal, which as best as I can tell, is the same as Form-a-gasket non-hardening liquid sealant,....

Ryan,

That alignment mechanism makes sense. More than dowels, TBH.

I wouldn't have considered this to be a maintenance issue so much (obviously, flushing salt water would be beneficial), rather just a function of time and the elements. Once the dissimilar metals are introduced to each other, especially under a load, quantum mechanics take over. I know we model boaters are borderline neurotic as far as maintenance goes, and we've seized plenty our fair shar of stainless screws in aluminum hardware and engine blocks. Obviously, there are other factors either at play or NOT at play that contribute to this, but the chemistry is the same. As I stated, it may well be the cathode we typically have keeping this from being the issue I'm thinking it would be.

The tooling I'm referring to are just drill bits, to the tune of $5-20 each, and the jig kit would likely be in the $100-200 range, thread-specific tooling aside. Most shops have a hand drill. This would be an operation very much like that of converting a conventional 4-bolt main block to a splayed main bolt block, for which there are jig kits available. A mill would, indeed, be an investment beyond a reasonable ROI if it were only for this purpose, not to mention the fixturing that would be required to capitalize on its true value for this purpose.

If this isn't an issue, I'm certainly not going to invest any time/effort/resources into solving a problem that doesn't exist. It just occurred to me that it might be something worth lending my expertise to.

All good. Carry on.

Thanks. Brad.

Auye, Perfect Seal for threaded parts? That`s for gaskets.

Perfect seal is indeed also a thread sealer... says so right on label. Works good too!