gasket material for fuel tank

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Prime Time

Prime Time

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Sep 25, 2008
544
Bristol 43.3 Perth Amboy
Hi,
I have an access plate on the top of a diesel fuel tank. In the middle of the tank is the mechanical gauge. The port is screwed to the tank with hex head machine screws. One of the screws leaks when the tank is full. The screw is not stripped. I assume I need to replace the gasket between the plate and the tank. Any ideas on materials and sources.

Perusing Mcmaster Carr's web page it looks like buna-n or nitrile would be a good choice. has anyone done this?
Thanks,
gary
 
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Tim R.

Tim R.

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May 27, 2004
3,626
Caliber 40 Long Range Cruiser Portland, Maine
I use neoprene. Works fine for diesel tanks. A roll of it at NAPA is fairly cheap.
 
Prime Time

Prime Time

.
Sep 25, 2008
544
Bristol 43.3 Perth Amboy
How?

Thanks Tim.
How did you cut the material? What thickness did you use? Do you make verysmall holes for the screws? Did you put any teflon tape on the screw threads?
Thanks
 
Tim R.

Tim R.

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May 27, 2004
3,626
Caliber 40 Long Range Cruiser Portland, Maine
I cut with both scissors and a razor knife. I used a leather punch to make the holes. The holes are 1/16" dia. less than bolt size. I forget the exact thickness but I would guess either 1/16" or 3/32".
 
Joetech

Joetech

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Apr 13, 2007
142
Catalina 27 TR Lorain, Ohio
Check compatability of the material with the fuel. 3M, Garlock are manufactures to name a few. DO NOT put teflon tape on the treads. Teflon will shear off into tiny strands and clog your filter. Teflon tape in only for tapered threads like pipe fittings. Never use teflon on straight threads. It's at best a waste of time and could do some real damage.
 
Prime Time

Prime Time

.
Sep 25, 2008
544
Bristol 43.3 Perth Amboy
Unclear

Thanks for the info.
What I can't understand is why there is a leak around just one of the screws. I removed it and retightened it. It definitely is not stripped.
 
B

Barnacle Bill

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Jun 9, 2008
1,792
- -- -Bayfield
You can also buy paper/like/cardboard material in sheets to be cut to size for aluminum fuel tanks.
 
caguy

caguy

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Sep 22, 2006
4,004
Catalina, Luger C-27, Adventure 30 Marina del Rey
You might want to try a little non hardening Permatex. I used it on my aluminum Sea Bee gas tank.
 
jibes138

jibes138

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Jan 27, 2008
3,086
ODay 35 Beaufort, NC
Why not just seal the screw instead of a whole new gasket? Get a flat washer for the head of the screw and then just put a gasket uder the screw head, or a fuel resistant sealant.
 
Jeff

Jeff

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Sep 29, 2008
195
Hunter 33.5 Carlyle Lake in Central Illinois
Prime Time, I sell gaskets for a living. Nitrile and Buna are the same thing. Neoprene will not stand up as well to Diesel fuel. It tends to swell more then the others. Generally you base your gasket thickness needs by the amount of variance there will be between the mating surfaces. In this case I suspect it's minimal and .062 would be just fine. If time allows measure the thickness of the material you take out before buying the new stuff. A middle of the road 60 durometer (hardness) rubber material will work unless any of the bolts are suspect. You must have good torque on all of them. Using a Loctite or Permatex product can be a good alternative. BTW it would be great time to clean out the tank. Good Luck.
 
Prime Time

Prime Time

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Sep 25, 2008
544
Bristol 43.3 Perth Amboy
Many Thanks

Thanks for all the advice.
I've been warned away from the permetex due to the problem it may create if I do need to redo the entire assembly. Any comments?

I like the idea of a stainless washer and a gasket on the leaking screw.

The tanks were replaced about 7 yrs ago.
Any ideas on why just one of the screws would leak?
 
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