GAS TANK GASKET

[JOFO17]

I have been getting water in my gas tank and from what I have read on here, the most likely source is a leak at my sending unit on the top of the tank. I have everything all set to pump out ALL of the old gas/water. The only thing I am unsure of is what gasket material to use on an aluminum tank/ sending unit. I have read posts with guys using rubber and with guys using cork. The same goes for using Permatex. Some guys use it and others say no. I just wanted to get a few opinions before I begin.

 

[Grub54891]

Most I have seen are cork. No sealer needed.

 

[smokeonthewater]

Sounds like you already HAVE a few opinions.
You can expect more of the same....

Use a product designed to withstand use with gasoline.

The manufacturer will specify what it works with.

Cork is a very common oem gasket for fuel tanks and works very well.

'Permatex' if you mean silicone then NO... They do make a product that can be used but personally I would suggest the cork instead.... It's all you need.

From the permatex website FAQs:

Can I use the Permatex? Ultra Blue? RTV to seal a gas gauge-sending unit to a gas tank?
-
No, Ultra Blue? is a silicone-based product, that will offer a good seal, and has good resistance to oil and coolant, however, silicones are not recommended for use in a gasoline environment. The gasoline will attack the product. Permatex? offers the solvent based Form-A-Gasket? products or MotoSeal? #29132 [hyperlink to 29132 product page] that are designed for applications in a gasoline environment.

 

[JOFO17]

I was referring to the Permatex 2.....gasoline resistant. Says on the package it is good for fuel pumps, gas tanks etc. If it makes a difference, I will be using the boat in a salt water environment. I don't know if any particular gasket material holds up better in a salty environment.

 

[GA_Boater]

How many screws hold your sender in place? 5 seems to be a magic number.

http://www.iboats.com/Replacement-G...0117799--session_id.305410472--view_id.483908

 

[Bondo]

and from what I have read on here, the most likely source is a leak at my sending unit on the top of the tank.

Ayuh,..... Are you gettin' gas in the bilge,..??

I don't buy the leakin' tank sender, at All,....

It's more apt to leak gas into the bilge, than water into the tank,.....

Mis-routed vent lines are the most likely cause of water in the fuel,.....

Some boats have the vent fittin' placed in a high splash area, which is bad enough,....
If there's not an upward loop at the vent fittin',....
All the splashed water, ends up in the fuel tank,.....

 

[JOFO17]

I have to agree with you Bondo. I took off the sending unit and the gasket looked fine. Pumped out all off the suspect fuel untl the tank was empty. Had some nasty jelly like residue left in the tank though. Im going to use a plastic Tempo gas tank until I figure out the best way to clean it. And sending unit has 5 holes.

 

[JOFO17]

I forgot to mention in tje last post. I'm getting no gas in the bilge.

 

[Bondo]

Ayuh,.... Yer more likely lookin' at a bad vent line installation, than a bad sender gasket,....

 

[JOFO17]

So I need to put a drip loop in the vent hose?

 

[Bondo]

Ayuh,.... The vent line should rise up, 'n away from the vent fittin',....
Before it drops down to the tank,....

The fittin' should be mounted in the hull, Away from major Splash areas,....

I've seen hulls with it right at the aft side corners, sunk by splash when gettin' onto plane,.....
Several I've had to replumb just 'round the corner to the transom, where splash never get's too,...

My ole tinbarge has 'em right as the bow turns into the side of the hull,..... Splash city,.....
Had a 'ell of a water in the fuel issue, til I put up-loops in the vent lines,....