[C320-list] Tightening don onto rubber gaskets?

[Scott Westwood]

FWIW,
I replaced the sending unit when I first bought the boat and it also leaked after a while.  I forgot the golden rule when it comes to using "any" rubber gaskets.  (Assuming you don't have specs and a torque wrench, etc...) Once I traced out the leak I was kicking myself for not re-visiting the replacement.  Couple of turns on some bolts and leak was secured.  No leak since.
1.Crank on it until secure (no leaks) Do not over tighten.2. Wait and come back and re-tighten after rubber settles.  Best done in warm weather.3. Repeat number 2 until rubber settles in.  Watch it.  Normally revisit 1-2 times does the trick.
I have not tried "sealant" but may investigate in the future.
Any time I use rubber gaskets, for anything, I assume they will compress and need to be secured once or twice until they settle into shape.
 

Thanks,
Scott Westwood scottwestwood at bellsouth.net H (919)-362-8538     C (919)-618-7185 

      From: Rick Sulewski <rsulewski at bex.net>
 To: C320-List at Catalina320.com 
 Sent: Monday, December 18, 2017 6:58 PM
 Subject: Re: [C320-list] Tightening don onto rubber gaskets?
   
Graeme,
Sounds like you have a very secure fuel sending unit. I doubt you could do better from what you explained. Regarding the gasket material, consider that different types or grades of gasket materials will compress at various rates. Some rubberlike gaskets are very hard or dense and therefore quite stiff and while other rubberlike gaskets are softer, more flexible and will compress to conform to surface variations. I learned when it comes to certain fuel components it is always wise to use fuel sealant gasket sticky goop (heavy liquid sealant) that adheres to a very clean surfaces when installing some fuel connectors or parts. Eventually after the sealant cures it become hard and may attach to surfaces like caulk yet can be removed by chipping it and lifting it away. NAPA  has a very good fuel sealant that can be brushed on fittings while it also works very well to seal screws and gaskets "just in case"  leaks may develop.  Cost is around $5.

Several years ago I installed a replacement sending unit on my 320 tank during the summer and topped off the tank in the fall. In the spring I learned  that fuel had leaked from the new sender unit at the gasket that was harder/denser than the original sending unit gasket. I cleaned up the fuel from the sender area with a degreaser, checked the screws that were very secure and then painted on the NAPA liquid fuel sealant as suggested by a NAPA store guy when I went looking for liquid gasket material and he recommended instead the NAPA fuel sealant solution. The fuel sealant solved the problem for two years before I finally replaced the aging tank.

 I decided I did not want to again find fuel under my hull liner because that was a pain to clean up after the leaking fuel sender gasket incident. My hull was approaching 20 years at that time and I anticipated (dreaded) the day when I would discover another messy fuel leak. I  elected to replace the fuel tank  before it started to weep due to its age as it was a thin walled tank.  I also ceased topping off the tank for the storage season and now leave the tank short about 2 or 3 gallons. It is also a good idea to turn off the fuel valve on top of the tank over the storage season to prevent a surprise leak and cleanup  in the spring from the fuel lines, fittings or from the fuel filters because a fuel tank that is more than one quarter full will still gravity feed a leak downstream from the tank, especially when the bow is raised while on the hard.

Rick Sulewski
95' 320 hull #277 
 

-----Original Message-----
From: C320-list [mailto:c320-list-bounces at lists.catalina320.com] On Behalf Of Graeme Clark
Sent: Monday, December 18, 2017 9:46 AM
To: Catalina list
Subject: [C320-list] Tightening don onto rubber gaskets?

I've installed a new fuel sender unit and added some fuel tank inspection ports. I have used 1mm gasket material for the ports (Viton material) and the sender unit had a 2mm gasket supplied.

I have also used hylomar non-setting gasket sealant.

Not having looked too closely at the old gasket when i removed the broken sender, I was surprised to find the extent to which the gasket material compresses and squeezes out to a diameter greater than the plate. I dont want to over tighten the screws (on a test piece when I did a destructive test the screws (stainless) sheared before the threads (aluminium) stripped, to my surprise).

On the other hand I dont want to leave any possibility for leaks.

can anyone give guidance on how tight i should be doing up these bolts - (no 10 self tapping flanged hex headed) either in terms of torque or in terms of how much gasket squish!

Cheers

Graeme
‘Jakar’, 1996, Hull 366.