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MG TD TF 1500 - gasket sealant question

This is a minor issue, but I thought I'd get people's opinions.
When I reinstalled my gas tank I did not use any gasket sealant on the tank sender unit, just installed new gaskets.
I finally got around to filling the tank yesterday, and I noticed a few drips on the ground beneath the sender unit. I felt up around the sender, and sure enough, it was wet with gas.
I thought I'd just drain the tank and take the sender unit off again and put some sealant on the gasket, no big job...

I went to check it an hour later and the unit was quite dry and the stain on the ground was drying up.

This morning, it's totally dry.

Here's my assumption: after fixing the tank and the sender, I never filled it, so the gas in the tank never rose to the level of the sender unit gasket, so it stayed dry.
I filled the tank yesterday and the gasket came into contact with gasoline for the first time, and leaked a bit. Then it swelled up enough to seal thoroughly so the leaking stopped.

So here's the question; should I put sealant on the gasket, or leave it alone? Do you think that now the gasket has been in contact with gasoline, it will keep a good seal?
Or if I let the tank level drop the gasket might dry out, and I would get another leak next time I filled it; for a while, until it swelled again and sealed properly. And the cycle might continue.

Should I just reseal it, or not worry? After all, it's got 15 gallons in the tank and it's dry as a bone!

Opinions welcome!

Geoffrey M Baker

Don't know what to say other than for now it looks fixed, so if it ain't broke ...
When it shows signs of being broke then try to figure out what's happening!
;-)

BobbyG
Bobby Galvez

If it ain't broke, don't fix it. If it used to be broke but now looks like it fixed itself, don't question it. ;)
Steve Simmons

I'm half-way agreeing with Bobby and Steve, though I'll add a caveat... I'd watch that join VERY closely for the next few months. I've rarely seen a gasket become 'self healing', and usually that's only temporary - the first time you get a major temperature or pressure fluctuation you're apt to have yourself a leaky join all over again. Given this is quite literally an explosive situation, I'd be watching it like a hawk for a while.
kmclemore

Geoff, did you use a cork, fiber or rubber gasket, also did you use the small teflon gaskets on the screws? I think FTFU's rubber gasket is the only one I would attempt to use without sealer plus the teflon washers on the mounting screws. Just my 2cents worth:)
Rich (TD 3983) Taylor

Rich it was the rubber gasket sold by Moss. There were small washers on every screw but probably not Teflon. I'm draining the tank now as I checked again and could feel a tiny bit of moisture. So I will add sealant. Thanks for the input!
Geoffrey M Baker

If you use a sealant, just be sure to use a sealant impervious to fuel and methanol. Silicon IS NOT resistant to either one. I've not had to do it, but most folk recommend Permatex Aviation sealant.
LD Palmer

I used Permatex #2 which they say is good for gasoline etc. It looks like it's working well! No leaks at all now.
Geoffrey M Baker

The only seal that I trust is the set sold by Abingdon Spares. Bud

Bud Krueger

Permatex aviation sealant has worked for 9 years so far , not a drop. Thanks to advice from this sites members.
Cheers, Keith
K. McKenzie

I use "Wellseal" which was recommended for the assembly of the engine in my Lotus Elan. I have tried petrol, turpentine and acetone to clean it off my hands all without any success. The only way to shift it is to use Swarfega mixed with dry sand. Hope no dermatologists are reading this.

Jan T

J Targosz

Bone dry two days later :)
It's always nice to take a step forward instead of a step back!
Geoffrey M Baker

I use Welseal for engine assembly as well, but I have to import it from England as it is not readily available here in the States. It is easily removed with lacquer thinner. Also. It pays to store the Welseal tube upright since if it leaks it is a REAL mess... don't ask me how I know this.
kmclemore

This thread was discussed between 11/03/2015 and 13/03/2015

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