Should I be concerned about my fuel tank?

[GT2BH]

As part of my rebuild and refresh, I decided to remove my fuel tank for a paint job while I change the fuel lines. I can't see clearly inside, but the fuel I drained seemed reddish. Since I pumped the fuel out from the fuel level sender unit I can't tell if there are pieces of rust inside. I rinsed it after removal but didn't notice any rust coming out. Upon inspection, I saw that the tank was repainted in the past, and under the paint is a layer of rust. Should I try to salvage it by stripping and repainting or go for a new tank since all my lines and engine will be new?

[douglas bray]

Get yourself a boroscope from Pep Boys and have a look inside it. You can even bench test it for leaks if you are feeling industrious. There are shops that specialize in resealing fuel tanks if you think it's borderline. Wurth makes the exterior texture paint.

[GT2BH]

Originally Posted by douglas bray

Get yourself a boroscope from Pep Boys and have a look inside it. You can even bench test it for leaks if you are feeling industrious. There are shops that specialize in resealing fuel tanks if you think it's borderline. Wurth makes the exterior texture paint.

Issue is I don't live in the States and don't have access to these shops.. its either DIY patch job and face a bigger problem down the line or get a new tank..

Seems like I made up mind doesn't it?

Does anybody know anything about this tank? It doesn't include the make but its very well priced
http://www.ebay.de/itm/Porsche-911-911S-911SC-Benzin-Tank-85-L-ab-Bj-73-/251658309738?pt=DE_Autoteile&hash=item3a9801106a

[E Sully]

If the interior is good and the exterior rust is superficial, you could strip the exterior and refinish it. Mine had some surface rust around the lip and bottom. I stripped it to bare metal and repainted it.
You should be able to get an idea of what the inside looks like by looking in the fuel sender opening. Also by removing the filter screen you show in the second picture. If the screen is clogged with rust, it may be too late. Since it is a CIS tank, if the inside is rusting, you would be better off getting a replacement tank. It has a plastic whirl pot attached to the bottom of the tank. Sealer would not adhere well to this and eventually clog the fuel lines.
CIS Gas Tank
As for the tank you show, you would have to check to see if it has the whirl pot. Very important to prevent fuel starvation. All Porsche tanks from the 1973.5 CIS on have it.

[Justin@Athens]

That area there at the seam where the rust is....is bad. That is exactly where mine started to develop pin sized holes and leak when over 1/2 full. What you need to do is have the thing immersed in a hot tank to boil out the inside really good, this will also serve to soften up the outside for removal. You will end up needing to wire wheel the outside probably, but it will need to come off. POR15 makes a gas tank restoration kit. It is basically just a coating for the inside, but you can use it on the exterior as well. In addition, I used some epoxy putty to plug the holes on the outside before I coated the exterior. If you do this, make sure to let the epoxy fully cure before coating the exterior. Some folks will say that because this unit has a plastic swirl pot in the bottom, that you should not use POR15 or redcoat, however I experienced no problems.

[Justin@Athens]

In regards to the ebay link above, the two things you really are going to worry about are the gauge steel used in construction, and the angle of the filler neck. These have been the issues with reproduction tanks in the past. I have no knowledge on this unit or seller though.

[GT2BH]

Thanks for the advice - I need to look around to see if there are any shops that can help me, but I doubt it.. we are pretty behind when it comes to this stuff..

How is the dansk replacement tank? will I face the same fitment issues?

[Justin@Athens]

A good radiator repair shop or engine rebuilder should have a hot tank big enough. From there, its all available over the internet: POR-15 Fuel Tank Sealer
Amazon.com: Permatex 09101 Fuel Tank Repair Kit: Automotive

Don't know about the Dansk tank, but I know the name well and trust their construction.

[Autoban]

You threw out the option to go for a new tank since "all my lines and engine will be new". Rust is like cancer and sometimes very hard to stop unless you cut the rusted metal out to where you have good solid metal. If it is an option, I would install a new (or very good used) tank so I wouldn't have to go back in a year or two and deal with a leaking fuel tank.

Juergen

[GT2BH]

Originally Posted by Justin@Athens

A good radiator repair shop or engine rebuilder should have a hot tank big enough. From there, its all available over the internet: POR-15 Fuel Tank Sealer
Amazon.com: Permatex 09101 Fuel Tank Repair Kit: Automotive

Don't know about the Dansk tank, but I know the name well and trust their construction.

They won't ship that stuff international because its flammable.. so that option seems to be out..

Originally Posted by Autoban

You threw out the option to go for a new tank since "all my lines and engine will be new". Rust is like cancer and sometimes very hard to stop unless you cut the rusted metal out to where you have good solid metal. If it is an option, I would install a new (or very good used) tank so I wouldn't have to go back in a year or two and deal with a leaking fuel tank.

Juergen

Yeah, I'm leaning towards a new tank since all my lines, fuel pump and EFI will be new.. my engine will have been just rebuilt.. might as well

[sugarwood]

Can you address some mild front lip surface rust without removing the entire tank? What are the steps to jacking up the front of the tank a few inches so you can wire wheel the POR15 the surface rust on the front lip of the tank?

[GT2BH]

I removed the bolts holding the tank down and unhooked the hoses from the bottom and top then used a piece of wood on my floor jack and jacked the tank up bit by bit. It'll work if you are trying to lift it, but I don't see why you don't just remove it. Its very easy. Make sure its empty first though

[Uwon]

If you buy a reproduction tank, make sure it has a centre pot, a baffle and a metric drain plug for the screen. Mine didn't so I sold it with full disclosure.
Then Bought a used one and fixed it up on the outside which looked like yours.
Good luck.
Johan

[Steam Driver]

TOUGH question. On my SC I tried to have the tank cleaned at a local radiator shop with a good reputation. (It should be noted here that the car had sat for at least 15 years beginning with about 3/4 tank of gas, so the inside of it and a lot of other places were a mess!) They assured me it would work out fine. The exterior paint came through fine (more or less; it was discolored some but there) as did the swirl pot. HOWEVER the metal threaded fittings for the fuel supply and return lines were destroyed! (I have images of these, but they not available on this computer. However you can search for them in the forum with "fuel tank" or something iike that, I'm sure.)

I ended up getting a used tank; not in as good an exterior condition as the one I had, but OK. I tried using the proper Wurth stone guard (or whatever) paint on it with zero luck; the stuff just refused to dry after days and days! I removed one attempt with gasoline (does this make sense for a coating where gasoline will be present?) and tried again - same situation. So that didn't work for me. I was originally going to leave it as is (OK) but have been told to recoat with common epoxy grey garage floor paint. Makes sense to me!

Anyway bottom line is you may just need to start searching for a replacement tank.

[GT2BH]

I just placed an order for a Dansk replacement tank with new fuel sender gasket, rubber seal and other hoses. The vendor told its made of painted steel so they recommend I paint it with rust protection paint. I plan on sanding it down once I receive it and coating it with Rustoleum Primer followed by Rustoleum Black paint. Meanwhile, I have rust and years of dirt in my compartment so I'm going to remove as much as I can, grind the rust and give it the same paint job.

[Discseven]

GT, here's some reference... looking at outside edge and inside of same tank. Not sure how old tank is---should have dated it on install. I know from replacing prior tank that seams rot... so I pulled this tank "early" to deal with rust. Am liking Doug's boroscope idea---more comprehensive inspection compared to looking in with flashlight.






Point is, inside of your tank may be fine. Before you sink dollars into new one... make internal inspection. Might be just an external rust-off job.

[Robert Adams]

Lots of good advice above. I'll assume this tank is out of your 83 so replacement is probably the cheaper & easiest thing to do in the long run; either new or used. Restoring one is a long and laborious process. Having a 73.5, my tank just isn't out there so I had to save it by having a ton of stuff done to it. Fortunately when I had it tested there were no leaks, but it was rusted along some of the outside edges and next to nothing inside. I lucked out! Once I got the tank back resealed inside and stripped outside, I used Wurth rust guard and SKS. The rust guard dries like iron and encapsulates the tank, nothing will penetrate it short of drill bit or saw. I'm sure POR has a product that will do the job, but Wurth is a international company and may be more readily available to you; just a thought.
Good luck!

[Discseven]

Originally Posted by Robert Adams

Lots of good advice above. I'll assume this tank is out of your 83 so replacement is probably the cheaper & easiest thing to do in the long run; either new or used. Restoring one is a long and laborious process. Having a 73.5, my tank just isn't out there so I had to save it by having a ton of stuff done to it. Fortunately when I had it tested there were no leaks, but it was rusted along some of the outside edges and next to nothing inside. I lucked out! Once I got the tank back resealed inside and stripped outside, I used Wurth rust guard and SKS. The rust guard dries like iron and encapsulates the tank, nothing will penetrate it short of drill bit or saw. I'm sure POR has a product that will do the job, but Wurth is a international company and may be more readily available to you; just a thought.
Good luck!

Robert... do you recall how much it cost to do your tank with Wurth?