Re: [Amel Yacht Owners] Illustration of the Onan Exhaust Elbow Replacement

James Alton


  My first introduction to Tef-Gel came when I completely disassembled the spar to be refinished on which Tef-gel had been used on every fastener 12 years prior.  As the boat had been cruised extensively in the Tropics I was expecting the worst.  Instead I found that every single fastener came out easily, I was amazed and have used the product with great results since.  I agree that this is a better solution than to use aluminum fasteners, the threads are too soft and they tend to seize up after a while.

  Thanks for giving me the brand of Never-Seez that you use,  copper is a little below stainless on the galvanic scale I believe.  I did not know that the Loc-tite 248 came in  lipstick style packaging as a gel/paste, that sounds like a much better solution than the small leaky liquid containers I have been using.

  I have had great luck as well with the Drip Less Teflon packing and also the white teflon impregnated packing.   

  Always great to learn something new, thanks for sharing.


SV Sueno, Maramu #220

On Sep 4, 2016, at 7:07 PM, Bill Kinney greatketch@... [amelyachtowners] <amelyachtowners@...> wrote:


Tefgel and stainless machine screws are the perfect solution to attaching things to aluminum spars.  I have had no trouble at all disassembling screws that have been in place for 15 years that were installed with tef-gel.  I know, because I put them in, and then took them out a decade and a half later.  Compare this to the trouble people have trying to take out the aluminum bolts that Amel used in an effort to avoid the issue. One of those things that must have "seemed like a great idea at the time” that didn’t work quite as well as expected.

The Bostik brand of Marine grade “Never-Seez” has “active” ingredients of copper and aluminum powder—no graphite.  I have used it on stainless steel piping carrying salt water and not had any issues. I have used it on bolts going into aluminum engine blocks without a problem.

Graphite packing material is one of those things that sounds like a great idea…  until you actually use it in salt water and your shaft erodes away.  When I was taking care of boats with stuffing boxes, I had great luck with the teflon based “Drip-Less” packing.

The blue loctite I like best is a gel or paste that comes in a tube like lipstick.  It is Loctite #248.  You have to look a little harder for it than your local hardware store, it is not on their list of “consumer” products.  As far as I can tell it has a very long self life.  Or at least, I lose mine before it goes bad!

One place that care needs to be taken with thread lubricants: If there is a torque specification on the bolt. The lubricated bolts put a LOT more tension on things than threads assembled dry.  You need to be sure that you follow the design specifications. 

Bill Kinney
SM #160, Harmonie
Narragansett Bay, RI, USA
“Ships and men rot in port."

On Sep 4, 2016, at 17:03, James Alton lokiyawl2@... [amelyachtowners] <amelyachtowners@...> wrote:


   Yes, apparently the “unflavoured” requirement was written right into the manual according to a good friend that worked with on the shuttle. (grin)

   I have had great luck with the Tef-gel,  especially when installing stainless fasteners in aluminum spars a very useful product.

   Have you ever seen any pitting or corrosion issues when using the never seize on pipe connections that are immersed in salt water?  I am pretty sure that some types of never seize contain graphite, which is quite high on the galvanic scale.  I have never seen a problem myself to date from using the product in that application but have seen corrosion issues on stainless prop shafts from using graphite impregnated packing so worry a little.  I definitely agree that something must be on stainless to stainless pipe joints.  

   What type of container do you buy your Blue Loc-tite in?  It seems that once opened the little squeeze tubes seep/leak.

   It really sounds like you know your how to deal with fasteners in the Marine environment..if there is a next owner to your boat, he is going to be a lucky guy when the time comes to take something apart!   Good point about taking new hardware apart to lube up the fastenings before putting it into service.  

   One of my first jobs when I get back to my boat will be to remove the bow thruster that has not been serviced in quite a few years.  Thankfully it appears that the previous owner was very careful about preventing corrosion since there appears to be plenty of grease between the tube and the motor and no obvious corrosion.  A dab of the right goo early can sure save a lot of stress and heartache later. 

    I have had really good luck by the way with using the special (which translates to expensive) Vari-prop grease (it appears to be a white lithium)  for winches, windlass clutch cones, applications where salt water tends to wash the lubricant away.  This stuff really seems to stay put and being white does not stain sails and lines too bad.  When you try to wash this stuff off of your hands, you understand why it takes so long for the Ocean to do the same!  

   Thanks for the tips,  if you have any more to share please do!


SV Sueno,  Maramu #220

On Sep 4, 2016, at 2:10 PM, Bill Kinney greatketch@... [amelyachtowners] <amelyachtowners@...> wrote:


Now that’s a fun fact!  But I guess magnesium hydroxide could be as good a thread lubricant as anything else.  Just be sure to use the “unflavored” variety.  :-)

I am not aware of  any single thread lubricant or anti-seaze that works in every situation on a boat.  I generally keep a few kinds in my tool box. 

A teflon based product like Tef-Gel for stainless screws into aluminum, and stainless-on-stainless threads under high load.  
Lanocote, for lots of general purpose applications.
Marine-grade Never-Seeze for most everything on the engine and any other high temperature applications.  Also good for preventing galling with stainless-on-stainless pipe threads.
Blue Loctite for things that need help staying together.

They all do something a bit different from each other, and which one that gets used depends on what I want to happen.  Do I want to lubricate the threads to make a tighter joint?  Is it a part that gets wet so galvanic isolation important? Is the temperature range unusual?  Is it an electrical connection so conductivity needs to be considered?  It is really rare that threads get tightened on my boat without something on them.

Just as an aside, one of the things that I find makes my future life happier is anytime I buy a new piece of equipment, especially if it has stainless screws, is I pull all the screws out and lubricate them.  A future disassembly then has much less aggravation.

Of course, these are the brands that I use because they are easily available to me, and have been good to me in the past.  I am sure there are lots of others that are at least as good.

On Sep 4, 2016, at 11:13, James Alton lokiyawl2@... [amelyachtowners] <amelyachtowners@...> wrote:

Bill and Alexandre,

   I thought that I would mention that the Kennedy Space Center uses (don’t laugh) Phllips unflavoured Milk of Magnesia on the threads of fasteners that will be exposed to high temperatures to allow for easy removal.  I have used this solution on exhaust systems of cars and boats for a long time and it really does work.  I am sure that there are other products and you may have as good of a solution but thought I would toss this in as an option.  Some of the anti seize compounds contain metals that are quite high on the galvanic scale which concerns me some...



SV Sueno,  Maramu #220

On Sep 4, 2016, at 11:22 AM, Bill greatketch@... [amelyachtowners] <amelyachtowners@...> wrote:


I would change the Lanocote.  At best, it will melt and run out of the joint leaving it unprotected.  At worst it would decompose in place and potentially glue the fasteners in place.  Lanocote is made from the grease from sheep's wool and will not survive in the 600 C temperatures of a diesel exhaust manifold.


On Sep 4, 2016, at 07:32, Alexandre Uster von Baar uster@... [amelyachtowners] <amelyachtowners@...> wrote:


Good morning Mark & Bill, 

Thank you so much for your input.  
I just added your note on the illustration.  

Bill, do you think Lanocote will made more bad than good (and should change it now)?  

Compare to some story I remember reading with similar hours, I thought the carbon built up was pretty reasonable on mine. 
Now that I have the Blue Sea AC Multimeter, I will be able to run appropriately the genset and minimize carbon build up.  

Thanks to both of you, hope more people comment.  
Have a great weekend!

Sincerely, Alexandre
Club Nautico de San Juan, Puerto Rico

On Sat, 9/3/16, Bill greatketch@... [amelyachtowners] <amelyachtowners@...> wrote:

Subject: Re: [Amel Yacht Owners] Illustration of the Onan Exhaust Elbow Replacement
To: amelyachtowners@...
Date: Saturday, September 3, 2016, 6:53 PM


Great job, and helpful
I only have
two comments.
 It is
not a good idea to reuse lock washers, especially in a high
temperature application like this.  They anneal and lose
their "spring" and do not do a good job the second
time around. 
You are
also right to use an anti seize on the bolts, unfortunately
Lanocote is not right for this application.  It will not
stand up to the temperatures of a diesel exhaust manifold.
 For engine work I use a product called
"Never-Seez" that is rated for higher
temperatures.  There are lots of others that work, most of
them are a suspension of powdered copper.
With a new gasket, and clean mating
surfaces I wouldn't use RTV on this unless I had
previous problems with leaks.  
Bill KinneyHarmonie,
SM160Narragansett Bay, RI, USA
On Sep 3,
2016, at 17:07, Alexandre Uster von Baar uster@...
[amelyachtowners] <amelyachtowners@...>


Reading about Gary Silver SM#335 Liahona, Mike Gough SM 378,
Mike Ondra SM#240 Aletes about their Exhaust Mixing Elbow
(and Exhaust manifold) being blocked with carbon build up, I
decided to purchase a spare Exhaust Mixing Elbow, several
Exhaust gaskets, and change mine as preventive maintenance,
having 2014 hours on the Onan generator.  

For the new owners like myself who are intimidated by new
maintenance they have not performed yet, I illustrated the
“Exhaust Elbow Replacement” on the Onan generator. 

Please do not hesitate to comment, especially if I made
error, as this can only be beneficial for our group.  

I can already say that re-reading Gary’s email on Feb 12,
2016, I forgot to add a thin coat of Permatex High
Temperature RTV…  

Here is the link:

For low bandwidth user, the document is split in 6 sections.

If bandwidth is not an issue, there is also the full version
(37 pictures).  

Sincerely, Alexandre


Club Nautico de San Juan, Puerto Rico

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