BlauerStahl

I have looked in the classifieds and such but no luck. The car is a 1980, no internal fuel pump just the strainer. The PO had swapped the fuel tank since the first one cracked and the car is currently on fuel tank #2. It was a used tank from 928Intl but within a few hundred miles, it developed a hairline (I mean hairline) crack that was leaking from the very bottom where the strap/support goes under the tank. I rubbed a bar of soap in the crack and that stopped it overnight and the next day I fixed it with some QuickSteel plastic tank repair. It has held for about 8 months until today. It seems to be leaking from the same spot, very very slowly. I could tear it apart and try to fix it but I think I would be back here again in 6 months. I am looking for a new to me/used tank. 928Intl "might" have one but they still need to get it out of the car and test it. It will be at least a week at the soonest. Sharktoberfest is coming and I would like to get her back on the road in the next 2 weeks if possible.

The Forgotten On

The best thing you could do with that tank is to plastic weld it.

Drill holes at both ends of the crack so it cannot continue to grow and use the same type of plastic the tank is made from to weld it shut.

This repair will generally last years and will expand and contract at the same rate as the tank, keeping it from cracking again.

It should last. BTW have you used foam on the tank strap like factory to keep it cushioned and not resting on the bare metal?

BlauerStahl

^^ Thanks and yes, I was willing to attempt a plastic weld but at this point that might be "plan B". I need to take it all apart to weld it so if I can get a new tank to replace it in the meantime I would do that. Then I can always have the welded tank as a spare. Plastic welds seem to work for some and not for others. Since two original tanks have already failed is welding any better? Or does it matter?

GregBBRD

I have used tanks. $750.

BlauerStahl

^^
GregBBRD, PM sent

BlauerStahl

After removing the tank welding it is not an option. It's trash. Quick question, how important is the year for fuel tanks? Seems they separated into 1978-82 and then 1983 and newer. Basically, would a 1987 tank fit in a 1980?

Kiln_Red

The tank is the same from '80-'95. '89 and newer tanks have the in-tank pump. Neither '87 or '80 have the in-tank pump. '80-'86 use the same main pump.

Hey_Allen

I have a tank from an '88 in my '78, the only real difference that I can see is the mounting tab at the top of the filler neck that is unused on the early cars.
It looks like this tank originally had an in-tank pump at one point, but a non-pump strainer was easily sourced and installed.

Kiln_Red

The early tanks ('78-'79) and '89+ could have the in-tank pump originally. MY88 should not have had the in-tank pump (unless option M460 - Australia, Japan) if the main pump was the correct Bosch 045.

BlauerStahl

^^ Thanks for the info! Learning more every day, even on these silly type questions. Much appreciated!

Hey_Allen

I don't know that this is accurate, but I'm not an expert on all things 928.
I did see that both pump options were visible on the parts diagrams, and my '78 (VIN: 716, for whatever that might be worth as to build date) has an external pump and associated fuel hoses that appear to be factory original.

Kiln_Red

I may not be understanding your post correctly.

The early cars and the 89+ cars have two pumps. The '80-'88 cars have one external pump. All 928s have an in-line, external pump.

997TTEQNY

I went through this over the summer

My 85 developed a bad leak all the way at top.

I ended up with a tank out of an s4 that I found at a local junkyard for $200.

So far, its holding up.

it would be nice if the aftermarket created an aluminum replacement as this is a losing battle for all of us.

ROG100

Apart from 78 all the tanks are the same.
Early tanks had a different sized thread sleeve for the in-tank pump/strainer. 36mm v 37mm from 79 onward. Also the bracket at the filler neck was not used on early cars but does not hamper fitment of late to early.
Cracks can be welded as long as you weld with the exact same material the original tank is made from. However not easy to do.
New tanks are readily available again for $1700.

We now have an insert to replace the threaded sleeve that often pulls out of the tank.

Hey_Allen

What I was trying to say was that my '78 appears to have had the two external pumps from the start, in reply to the comment that the '78-79 would have had an internal pump.
Mine has an external under the tank, and then another next to the filler neck portion of the tank, behind the right rear wheel.

That said, it's immaterial to the main discussion, as the OP can fit any later tank with little problem.