In the process of working on this car for it's owner,, rebuilding carbs, distr' gen' re-polarizing, etc, etc etc,, I also found out that the 3 gallons or so of gas that is in the tank is about 6 years old, so I drained it and have blown out and cleaned the lines, and screens etc. But apon taking out the tank for cleaning I noticed that it has ALOT of rust. The outside is beautiful, but this inside is in a bad way. Not rusted through, or with any leaks, (yet) But it clearly needs to be refinished and sealed for modern and much more corrosive fuels.

Do any of you have preferences? Based on this is the OEM original tank, the car is DROP DEAD gorgeous ( a controlled environment garage queen) Aside from having a load of (bad) shade tree mechanic work on it in the past. And other than an ugraded (Porsche) steering wheel, and replica air cleaners, it's all original. The owner does not have a budget. He just wants it to be right, and keeping it as concourse as possible has become increasingly important with age.

Any input/caveats are really appreciated. Normally I would just get a replacement tank, but in this case, the owner wants all the original parts left on the car.

Thanks in advance! Paula

 

If it is really rusty, it may be best to cut your losses and replace it.

https://www.stoddard.com/shop/shopexd.asp?id=62341

 

I have used Kreem products to restore a ancient bsa Motorcycle gas tank that sounds like it was in similar shape--used a kreem product that prepped inside then another one that sealed it--its available from a number of places and worked very well for me tho a bike tank is a much easier thing to slosh stuff around in to cover all surfaces--

 

there is a stuff called sloshing compound, used to seal such tanks - I had a perfect tank and I let the car sit with gas for years - the gas congealed and the tank was now rusty - so I bought one of the gas tank sealing kits from one of the vendors that advertises in Hemmings. Another alternative is to have the inside tinned - that is a great solution and does not involve discarding the original tank.

 

xtended Range tank rattle

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Extended Range tank rattle

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#1

Porsche992 , 10-26-2022 06:39 PM
Racer
Thanks to user @Bluehighways i was able to identify a rattle coming from what seems the dash, behind/under the stearing wheel in my 992. A rattle that in reality originates from the extended range fuel tank. Apparently there is a design problem. Its confirmed in my case that the rattle does come from the fuel tank as it dissapears when the fuel level is in the mid tank.

i took my car to service twice and they were not able to completely solve the issue. What my tech did was add padding around the tank, it greatly helped but im still hearing some noises on brick roads and specific places. My question is..

If you have an extended range tank and had this issue, was service able to solve it completely for you? I know Blue Highways solved it , but im wondering if theres something i can tell my service advisor. My other option is to take it to another service center but i feel it will be experimenting again as this is not something they see everyday, actually in my tech’s case it was the first time he has seen this. Any thoughts? Thank you!
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#2
eagle1960's Avatar
eagle1960 , 10-28-2022 12:44 PM
Rennlist Member
I don't have the extended fuel tank, but I suspect the cause is the same as for the regular tank. I just completed a fix on mine after trying to get the local dealer to handle it. You will need a dealer, and especially a tech that is willing to do some thinking and devise a fix that won't be found in the Porsche school books unless you tackle it on your own. My fix was really simple. The bottom of the tank is accessable by removing the first belly panel. A lift is a must. I have a set of Quick Jacks. There are 2 straps holding the tank. There is a hook on one end and a bolt on the other. There are also 2 short aluminum chassis members that could be removed to make working with the tank straps easier, but I left them in place.
When I removed the first tank strap I could see a thin white line on the tank a both ends where the strap breaks over to meed the attachment points. It was the same on the other strap. To me, that looked like novement had been occurring at those points. I cut 2 srips of closed cell foam slightly wider than the straps and worked those between the straps and the tank. The foam was from a piece os cylindrical pipe insulation I had lying arould the shop. Sorry no pictures, and no, I am not doing it again to make some!!

 

I had the fuel tank of the old Land Rover I'm restoring etched and coated with a fuel tank sealer on the inside by the local radiator shop. They use a special coating like the POR15 or KBS products that are readily available. Cost was about $150 and its about the same size as the 356 fuel tank.

 

Here’s what I did. After sealing all openings, I used Evaporust to dissolve the rust. I poured enough in to coat half the tank when lying flat to the surface being treated. After 24 hours I flipped the tank over to treat the other surface. Then I rinsed the tank thoroughly with water per the Evaporust instructions, and then rinsed with rubbing alcohol to absorb the water. I placed the tank in the sun to dry with all openings unsealed. I did not coat the inside with a sealer because ive read about the sealers causing problems later if they break down or separate.

 

These tanks get rusty and thin - Why not buy new exact replacement Dansk tank
$462 Including shipping

https://www.ebay.com/itm/37487764847...RZMKD7F46X01PV

 

Paula,

Not want to dismiss the Rennlist 356 forum, but I strongly suggest you or the owner of this car join
356 Registry.
They have a lot of downloadable material and a lot
of very experienced 356 people that shere their
knowledge.
Check it: https://porsche356registry.org

 

I would suggest replacing your gas tank with the Sierra Modre repro
They are an exact match and great to have no rust issues

https://www.ebay.com/itm/226378064544