Porsche 911 Fuel tanks

[10musketeer]

Anyone know anything about 911 fuel tanks? It apears I have some sort of corrosion at the front of the tank right next to the battery. It apears to be a soft bubble that has air, or possibly some fuel in it. It seems to be about the size of a silver dollar and I can push it in about a 1/4 inch, and then contact something hard. It feels as if the outer skin is just bubbling away.

Any thoughts would be helpful, as I can't find a good forum to ask this to, so I thought I'd start with the guys that always help me the most!

 

[Steve]

There are a few Porsche guys on the forum, one of them is bound to spot this and jump in. I would doubt that there's rust given the location of the tank, but I am no expert.........

 

[DrEntropy]

Hmmm... what it -sounds- like is the tank has corroded from the inside, pressure is causing the protective stuff they coat the outside with to separate and create that anurism. Look over the highest places toward the bulkhead too, for similar ugliness. Only other thing I can think of is the "skin" may have a place it's been nicked to metal and battery acid or vapour has made its way between the two. My bet is inside tank rust. Pinhole. Only way to know is open it up... then you have another problem if it IS getting fuel tank pressure: cabin fumes. Either way, you'd be best off to deal with it soon.

Let us know how you get on with it, too?

 

[10musketeer]

I havn't had a chance to take the car to anyone who would know anything about this.

Here is a picture of what I'm dealing with. There doesnt seem to be any fumes in the trunk and the "bubble" seems to be intact and not broken.

What's the best forum to go to for 911's? I see a lot of forums, but most are full of " here is a pic of a girl with my car", etc. Interesting, but not really educational. I'm feeling lost without a forum like this one! /bcforum/images/%%GRAEMLIN_URL%%/smile.gif

 

[DrEntropy]

That is decidedly not a good thing, John. Corrosion under the coating, looks like battery acid to me. You'd do best to "yank th' tank" and clean/repair it. It's going from the outside, in. May not be through ~yet~, but it will be. The tank ain't too hard to remove in one'a them things. Have you access to the *factory* books? That'll be the best reference.

I know, I know... $$$! But: Take 'em one at a time and "collect th' set" if you intend to keep the car. The electrical system one is invaluable.

What's the best forum to go to for 911's?

And this is something we don't talk about 'round here, so "shhh..." But: <whisper mode> <span style='font-size: 8pt'> I'm a factory trained (VOA, Lanham, MD) Porsche wrench.</span> </whisper mode>

Or just abandon the "Cardigan 'n Penny-loafer" crowd altogether and come on over here permanently! Grease under yer fingernails isn't "off-putting" around here. /bcforum/images/%%GRAEMLIN_URL%%/smirk.gif

What year 'n suchlike is this thing?

Oh! And DON'T take a grinder to it! /bcforum/images/%%GRAEMLIN_URL%%/jester.gif

 

[10musketeer]

Thanks for the info. The car is a '82 911SC. I think I'll replace the open cell bettery as well and go with something less likely to leak.

I do have a Haynes manual as well as the Bentley manual. I think I'll try to get on this ASAP so I can see what I got.

I assume when you say no grinder your talking about the galvanized body? I do need to address some small rock chips, but other than that she's in pretty good shape.

Thanks for the "insight" /bcforum/images/%%GRAEMLIN_URL%%/smile.gif . While the other Porsche dedicated forums are ok, I still think I'll stay with the BCF as much as I can. I just havn't been able to find the kind of people anywhere else that are here on the BCF.

 

[DrEntropy]

I assume when you say no grinder your talking about the galvanized body? I do need to address some small rock chips, but other than that she's in pretty good shape.

I was referring to that "bubble" on the fuel tank:

We don't wanna lose a Porsche owner who thinks the BCF is a better place than a Porsche forum for help with it! /bcforum/images/%%GRAEMLIN_URL%%/jester.gif /bcforum/images/%%GRAEMLIN_URL%%/devilgrin.gif

 

[bugimike]

/bcforum/images/%%GRAEMLIN_URL%%/iagree.gif Ach zo Herr Doktor!!!!! /bcforum/images/%%GRAEMLIN_URL%%/jester.gif

 

[DrEntropy]

mehheh. Danka.

We can EASILY keep any of John's Midget questions/problems at bay... there's a few of us here who're 911 familiar as well, so I think it only makes sense.

You're stuck with us, John! /bcforum/images/%%GRAEMLIN_URL%%/thumbsup.gif

As for the exterior chips; get the Porsche touch-up paint wot matches your paint code, FORGET the stoopid brush in the cap: use a #00 or #000 sable Grumbacher from an art supplier. Clean the chipped "divot" VERY well with a cotton swab *moistened* (not sloppy-wet) with soapy water, several swabs and repetitions. Idea here is adhesion... NO wax, dirt or 'foreign substances'. Rinse it well, air dry with yer mum's hairdryer (just air, no heat) and dab the touch-up color in the 'hole' just to the original paint at the edges. A bit of overlap is no problem. This needs repeating over a few days (allowing the stuff to dry) until the level of the touch-up paint looks like a "pimple". After it's been there for a week or so, you can take a small piece of wood or plastic wrapped in one layer of #1500 'wet-or-dry' sandpaper and water to it to level it out. Buff, wax and all will be fine. Patience is the most valuable tool in this "kit."

If all that is redundant to your experience, please forgive!

 

[10musketeer]

Haa! I was just going to ask if you had any tips for painting rock chips! I tell you what, you keep this mind-reading thing up and I may not need any forums at all! /bcforum/images/%%GRAEMLIN_URL%%/smile.gif

 

[DrEntropy]

Dunno if you've read it, but this forum has that reputation: Answers to questions even before they're asked...

It's a gift. /bcforum/images/%%GRAEMLIN_URL%%/smirk.gif /bcforum/images/%%GRAEMLIN_URL%%/devilgrin.gif

 

[DART]

Dunno if you've read it, but this forum has that reputation: Answers to questions even before they're asked...

It's a gift. /bcforum/images/%%GRAEMLIN_URL%%/smirk.gif /bcforum/images/%%GRAEMLIN_URL%%/devilgrin.gif

so are you Doc, so are you!!

 

[DrEntropy]

awww, stop it...

You're embarrassin' me. /bcforum/images/%%GRAEMLIN_URL%%/blush.gif

 

[DrEntropy]

Any progress on this, John?!?

 

[10musketeer]

Just today I went to the nearest Porsche service center/dealer (unfortunately without the car) and they said that if there is any type of damage or corrosion that their only fix would be a new tank. They said that they were unable to do any repairs to a tank other than a full replacement. Does that sound about right to you? It's pretty spendy, but a new tank that I put in may be cheaper in the long run than getting it repaired. I'm pretty sure it wouldn't be a cheap fix, and sounds like Porsche wouldn't "approve".

 

[DrEntropy]

Sounds right for a Porsche shop, sure. They can't make any money on tryin' to fix the existing tank. And the liability issue is part of the story, too.

As I said above, they ain't that hard to get out of the car. 6~8 bolts and some tubing, IIRC (not counting trim, carpet, draining the tank an' suchlike). A radiator shop may be an alternative to "The Dealer." Ask around, find an independent place and remove the tank yourself. I wouldn't say the word "Porsche" when describing the problem, either... /bcforum/images/%%GRAEMLIN_URL%%/wink.gif

A thought: If it were here, I'd be pulling the battery and all "soft" materials out of the way and doing a "biopsy" of the thing. If it's as I suspect (battery acid corrosion) and you get to it in time: i.e. if it hasn't yet gone through the tank, it'd be an attempt at cleaning & neutralising the corrosive then coating clean metal with a good undercoat material, tank in-situ.

 

[SteveL]

Sounds right for a Porsche shop, sure.

A thought: If it were here, I'd be pulling the battery and all "soft" materials out of the way and doing a "biopsy" of the thing. If it's as I suspect (battery acid corrosion) and you get to it in time: i.e. if it hasn't yet gone through the tank, it'd be an attempt at cleaning & neutralising the corrosive then coating clean metal with a good undercoat material, tank in-situ.

Get it out, and get it to a radiator shop, have it cleaned and
and inspected, if it holds pressure, undercoat. If you want to
do it right, get it Linex coated, and never worry about it...

SteveL

 

[10musketeer]

Yep, I'm sure that's the best thing to do. I hadn't thought of a radiator shop, but I think that's the ticket. Worth a try anyway considering reman tanks are 400+ and a OEM one is $1000. Of course everything in these seems to be right around 1K! /bcforum/images/%%GRAEMLIN_URL%%/smile.gif

 

[10musketeer]

So after running the fuel down as low as I dared and mustering up enough courage, I took the scalpal and performed some surgury on the "bubble" on the fuel tank. To my surprise under the rubber coating was air and a ton of corrosion powder. I cleaned off what I could, neutralized it with the fancy foaming spray, and was surprised to see the metal in fairly nice shape. I tool a dremel tool with a wire wheel and took a little surface rust off and then put a little more of the anti-corrosion on. After filling the tank and making sure the tank wouldn't leak (which it didn't), I covered the bare spot with some rubber undercoating. The only problem was I didn't have any of the light brown/grey covering and had to use the standard black undercoating. At this point I think that I've run into the best case scenario- cheap and easy! Now I just wish I would have gone after it a little sooner so I wouldn't have to worry about it! /bcforum/images/%%GRAEMLIN_URL%%/smile.gif

Thanks Doc for the advice! Sounds like your biopsy plan worked. /bcforum/images/%%GRAEMLIN_URL%%/thankyousign.gif

 

[DrEntropy]

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