Fuel Tank Filler Neck Grommet questions (and others)

[marc70challenger]

Went out few weeks ago to fill her up for first time.  Wife followed me (QA/QC  lol).  I had about 1/3 tank fuel on way - got on it on highway, took left and right turns ... no problems .. no leaks, no smoking, nothing.

Filled her up, and drove home.  Got on it ... I could smell gas.  Wife saw gas spraying out right rear.  Every left turn I took (hard or not) .... gas dripping (or pouring depending on speed).  Right turns .. no issue.  At first I thought I overfilled it up the neck, and it was coming out the vent (70 Challenger) ... but when I crawled underneath, the gas left was pooling on the mid-lip of the tank in the back ... not coming out of rails where vent appears to end.

Got to play with her today ... I was hoping it was an overfill issue ... nope.  Drove around our cul-da-sac .. clockwise - no prob.  Counter-clockwise .. still pouring out ... tank indicating 3/4 (I've run her for a bit passed few weeks to get level below "full")

Again ... get underneath ... its pooling on mid-lip of tank.  I go into trunk ... gas actually go up in where filler neck dust cover is (see white circle).

So ... I am thinking one of two things ...

1) hole in top right of tank somehow ... but .... the tank looks almost brand new ... as is most everything in the restoration

2) fuel tank filler neck grommet is leaking .... see pics below ... there's rust line just below it ... could be that's where condensation sets ... or .... leaking fuel is eating the finish and tarnishing neck ...

The grommet "feels" ok .. not brittle ... but I can pull it easily away from filler tube with finger tips ... and it looks like they put some white piping stuff or something there

Quick questions:

a.  Does it "appear" like what others who have had this confirmed issue before?

b. I found this thread concerning replacing it (http://www.cuda-challenger.com/cc/index.php?topic=59170.msg609568#msg609568) ... my dust cover and gasket where filler neck meets quarter panel is fine ..... do I just need grommet?

c.  Aside from lubing the neck, anything else aside from grommet I can do or use to ensure it seals?  Like Permatex 80019 Aviation Form-A-Gasket No. 3 Sealant applied where grommet seats in tank opening?  And/or on neck where it goes into grommet ... but I guess it would be impossible to slip/slide it into grommet with that on it ... 

d.  The link above says he didn't have to drop the tank completely, just loosen straps to get enough play ... but Mopar manual says you should be able to get filler neck out, then drop tank ... anyone been successful doing this.

Any other suggestions or hints would be great appreciated!!!!!!!!   

I'd rather not drop tank and I will be pissed if its not the grommet and some issue with top of the tank.

I am mulling sending it to reputable shop around here for this and couple other minors things .... but rather do it myself (quicker and hate anyone touching it .. lol)

Thanks all 

[Bullitt-]

If I were betting it would be on the grommet, that being said I do not see evidience directly below the grommet of a leak, maybe I'm just missing it.
It does appear that something has run down the side of the tank from above. If this is the case I'd say remove the tank to inspect. 

  maybe jack the left side of the car up as high as possible & see what you can observe.

[anlauto]

I agree, the filler neck seal "looks" to be okay

[dfrazz]

It does appear to be some fluid marks running down from the top, but there is nothing up there to allow leaks.  You might want to check where your fuel lines attach.   

[marc70challenger]

Thanks guys.

The fuel lines appear ok (they are dry just after this happens) .. and grommet appeared dry itself just after checking incident ... and yes .... with streaks it must be coming from top of tank ... argghhh

One thing I forgot to mention ... there doesn't appear to be any pad between tank and body .... body is coated ... but .... even at factory, wouldn't/didn't they put some kind of pad .... or at least for a restoration I would think they would .....  strange ...

thanks for help!

[dfrazz]

Yes there should be a pad, but I doubt it rubbed enough to cause a hole in the tank.  Since you bought the car already restored there is no telling how the installed the tank and what is leaking at the top with out dropping it.  Obviously fuel leaks are serious enough to take the time to fix it right.

[marc70challenger]

Yes there should be a pad, but I doubt it rubbed enough to cause a hole in the tank.  Since you bought the car already restored there is no telling how the installed the tank and what is leaking at the top with out dropping it.  Obviously fuel leaks are serious enough to take the time to fix it right.

Weird there is not pad ... with other details of the restoration why they didn't ... but oh well.

And for sure .... leaking fuel I don't want to mess with.

I need some bungs welded and hose fabrication (which I don't have tools or know-how) .... so I'll bring it to recommended shop.  I could drop tank myself ... but our lift isn't in yet ... don't want to deal with 12+ gallons of fuel, etc ... 

Thanks for all help ... will be interesting to find out where its coming from ... very odd ...

[anlauto]

While you're under there on the passenger side looking up at the grommet around the filler neck................Have someone push the car sideways from the driver's side trying to shake the car back and fourth...if your tank is still pretty full, you should be able to tell if it's that grommet or not    

[marc70challenger]

While you're under there on the passenger side looking up at the grommet around the filler neck................Have someone push the car sideways from the driver's side trying to shake the car back and fourth...if your tank is still pretty full, you should be able to tell if it's that grommet or not

Great idea ... we tried that .. not grommet.

Next week and week after I have to go to Cleveland Clinic for rad treatments .... and though I think the shop is reputable - I don't want to leave car there for so long ... so I'm going to drop tank myself this week ... check it out and test it ... if so - replace it ....

Aside from tool to remove sending unit, new sending unit gasket, new neck grommet and gasket where it goes to fender .... (and tank lol) .,.. anything else I might be needing?  (oh - there is a mat between tank and body .... but its off center ... way off to left/drivers side ... ) ...

Give me chance to fiddle this week and weekends between running to the clinic .. and keep my mind busy

Thanks everyone!!!!

[marc70challenger]

Oh .. 2 more questions:

a) The filler neck .. it is bit surface rusted ... is that normal .... isn't it stainless steel (maybe not if original) .... is that ok to reuse .. just clean it?

b) when replacing sending unit on new tank .... do you use Permatex 80019 Aviation Form-A-Gasket No. 3 Sealant  with rubber gasket?

Thanks again 

[burdar]

The filler necks are "lead" coated.  You can rub them down lightly with steel wool and wadding cloth.  That's what I did with mine.  After I had mine done, I learned that someone does re-lead them.  I'll be sending my Dart's filler out to be re-leaded.  I think Wilson Products is the place that does them.  That was off the top of my head so research it if that's something you want to do.

You shouldn't need any adhesive for the sending unit however, some of the replacement gaskets are thinner then the original ones.  Also, the new locking rings are a little thinner.  That can lead to a leak.  Save your original locking ring...clean it up and reuse it.

[dougs bs23]

Shouldn't the groove on the filler neck grommet be turned the other way where it sets in the narrowest part of the tank hole?  I had mine on upside down and it leaked. Turned it over slid it into the groove and no more leaks.


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[CudamanTom]

Could it be a vent line leaking? I don'tknow much on Challengers but if it was a cuda, I would suspect a vent line since it only does it when turning left.

[jimynick]

Could it be a vent line leaking? I don'tknow much on Challengers but if it was a cuda, I would suspect a vent line since it only does it when turning left.

Yep, I'd certainly check there and that, because if it doesn't leak at the filler tube, the only other openings are for the vent or sender, unless it has the previously mentioned hole rubbed through it. Be careful here, because one little source of ignition with all that slopping gas and your pretty car is a crispy critter and having you and or your family and home in the calculation make it even more critical.

[Chryco Psycho]

I wonder if it is leaking around the sending unit lock ring , some new tanks do not seal well there