Repair or replace gas tank

[Pedro '84 Coupe]

Removed my gas tank today. Am wondering if the rust along the seams is bad enough to warrant a new tank or if I should try repairing it. There is a radiator shop nearby that used to repair gas tanks but they say they don't work on them anymore. I may have to take it to a place in New Orleans. The inside is pretty clean from what I can see. There is also a spot that needs to be repaired on the top. One of the POs drilled holes in the tank to mount an amp It was patched a few years ago and seems to be holding up ok but would like it fixed correctly










A little surface rust on the battery tray. Nothing serious thank goodness.

[jlex]

The inside of that tank looks clean as a whistle. Wouldn't worry about the interior. Why not just take a wire brush to the edges, then kill the rust using phosphoric acid, then prime and paint it. Is definitely a do it yourself project. If you don't want to fiddle with it, take it to any body shop. They'll probably sand blast the rusty spots, then prime it for you.

[dustim04]

+1 on painting it. Por15 is great for rusty surfaces.

[Ian Comerford]

If the inside is definitely clear of rust then I’d go for a repaint. I had this issue shortly after buying my 911 22 years ago and decided to be sure by cutting open the fuel filter to see if it had much rust in it. It did, so I bought a new tank.

[wildcat077]

Definitely fix it ...
Good advice from Dustim on the Por15, after you spray some Wurth undercoating and it'll be good for another 30 years !

[Arctic Rat]

https://www.pelicanparts.com/More_Info/93020101005.htm?pn=930-201-010-05-M350&gclid=Cj0KCQjwvr6EBhDOARIsAPpqUPFR0O2tpgK_h3NOIBj7 IOmgu8FHUNodvc-pOfiOEAW6Nu_3i5cqxboaAj1GEALw_wcB

$500 for a new tank from our host. What is your time worth? Add a couple 100 for stoneguard, gaskets, new filters.

Gasoline related items and brakes not places to save money, if you are not sure how to do the work the cost of the mistake is large. If you enjoy the work and know how to make a good repair do it.

[TxGerman]

I "restored" my tank last fall. Inside was pristine, outside had little rust. I used a wire wheel on my angle grinder to remove all the rust to inspect the base metal. It was minor rust so I continued. I eventually removed all the original Wurth stoneguard and put all new Wurth stoneguard on. I replaced all gaskets/seals, filter/drain, fuel level sender, some/most fuel line and installed a new fuel pump. It was quite a bit of work, but I was pleased with the results.

[pavegeno]

Had the same. Repaired it but several years later it was rusting again. Replaced before leaving Germany. If the money isn't an issue, better to buy new and replace then wind up without a replacement available in a few years.

[DavidMn]

Originally Posted by Arctic Rat

https://www.pelicanparts.com/More_Info/93020101005.htm?pn=930-201-010-05-M350&gclid=Cj0KCQjwvr6EBhDOARIsAPpqUPFR0O2tpgK_h3NOIBj7 IOmgu8FHUNodvc-pOfiOEAW6Nu_3i5cqxboaAj1GEALw_wcB

$500 for a new tank from our host. What is your time worth? Add a couple 100 for stoneguard, gaskets, new filters.

Gasoline related items and brakes not places to save money, if you are not sure how to do the work the cost of the mistake is large. If you enjoy the work and know how to make a good repair do it.

I wish they sold a tank with an internal fuel strainer, also with a stone guard type coating. Would be willing to pay double the price for these features. I ended up just punting and using POR15 to clean up the exterior issues.

[chrismorse]

I pulled my tank to clean it after a 9 year restomod and have a look at the aparent rust on the seam. As i wire wheeled and scraped the top and bottom edges of the seam, i found rust perforation under what appeared to be normal looking stone guard - I also scraped and cleaned the bottom where my dad had encountered a few rough roads.
I bought a TMP, (Tasker Metal Products) tank from our host because it was galvanized and came with a screw in filter like the stock tank. I painted it with Por 15 and shot Rhino Liner stone guard on it, in particular because i felt the bottom side of the tank needed some road protection.
I noticed that the brass mesh filter on the TMP tank was significantly coarser than the stock unit, so i reused the stock filter.

I did some beta testing/development with Len to fit a new front pump mount into the 74, as well as installing Len's new tunnel lines. I believe he has a good 10 micron pre filter for attachment to the front pump if your tank does not have a filter.
good luck,
chris

[Pedro '84 Coupe]

Thanks very much for the input, guys. I'd really like to fix the tank since it's original, the inside is clean and it has the in-tank filter (replaced with Porsche part about a year ago along with the fuel pump and fuel lines). I don't mind buying a new one (all I can find is the Dansk repro) if I can't get the top of this one welded and have already contacted Len Cummings about his pre-filter kit. My only other hesitation is that I'm a terrible painter and will surely mangle applying the Wurth stone guard. Will keep y'all posted

[Pedro '84 Coupe]

Went ahead and bought a Dansk replacement tank. With the foam seal, new sending unit gasket, two cans of Wurth underseal, Len's filter kit, shipping and tax the total is $710. I bought some stuff to treat the surface rust near the battery tray and need to get some paint but those will be less than $50. Will post pics once the new one is installed

[Tyson Schmidt]

Dansk replacement tanks for the post-73 cars have issues.
They don’t have a provision for a pickup screen like the factory tank.

And there’s no room to put an in-line prefilter.
And there’s lots of slag in them from the soldering process.
So I’ve seen a number of fuel pumps lock up from debris despite thorough cleaning before installation.

So in short, keep your original tank if at all possible.

[Pedro '84 Coupe]

Thanks. Am keeping the original tank but am confident Len's filter kit will help prevent any problems. These pics are borrowed from elsewhere on the forum but show that it is possible to fit an inline filter in this tight space. I think I will have to reverse the fuel pump to get it to work. Hopefully I can do this without too much stress.

[76FJ55]

Originally Posted by Pedro '84 Coupe

Thanks. Am keeping the original tank but am confident Len's filter kit will help prevent any problems. These pics are borrowed from elsewhere on the forum but show that it is possible to fit an inline filter in this tight space. I think I will have to reverse the fuel pump to get it to work. Hopefully I can do this without too much stress.

the factory tank has a screen on the outlet, where the Dansk tank doesn't. I don't know that you will see any significant advantage to adding the the pre pump filter with the factory tank screen in place.

[Pedro '84 Coupe]

Sorry. I wasn't clear. Meant to say "Am keeping the original tank as a spare..." The filter kit is going on the new Dansk tank. I plan to flush the tank with a few cans of carb cleaner and then a couple gallons of gasoline. Hopefully that will remove most of the large bits before the gas gets to the filter.

[Tyson Schmidt]

Glad to see you have a prefilter planned.
Tanks are fine otherwise.

The swirl pot inside doesn’t have a lid, but that doesn’t matter much.

[geoff_k]

if you repair the tank use an aircraft spec tank repair kit. I tried the one for a car and it was a waste of a lot of time.
The aircraft kit was a bit more expensive but worked perfectly.

Here is my tank after repair

[Pedro '84 Coupe]

Originally Posted by geoff_k

if you repair the tank use an aircraft spec tank repair kit. I tried the one for a car and it was a waste of a lot of time.
The aircraft kit was a bit more expensive but worked perfectly.

Here is my tank after repair

That looks nice! I kept the original so if the Dansk craps out I will definitely keep this in mind.

[Pedro '84 Coupe]

Got the replacement tank installed. Couldn't have done it without the help of Len Cummings. He worked with me so I wouldn't have to reverse the fuel pump. Super great guy to deal with for sure.

The Dansk tank seems like it's well constructed. Per their recommendation, I sprayed two cans of carb cleaner and then rinsed it with some of the gas that I'd drained from the old tank. Then I got to work with the Wurth undercoating spray and the spray paint. Ended up using Krylon smoke gray. I know it's probably not close to the original finish but I'm not picky.






I didn't want to flip the fuel pump so I asked Len to help me out. My idea was to have another 180 AN fitting connecting from the tank outlet and he suggested I try a 150 degree instead. Was pretty tight but was able to get it in there and the fittings or filter won't interfere with the pan. I may trim the hose that connects to the 150 but it should be OK.


Will put some ethanol-free gas in there later today and check for leaks then hopefully start her up. Have missed driving it