atb

Have a fuel leak coming from under that triangular shaped shield that is attached to the fuel tank straps and protects the fittings at the bottom of the tank.
Anyone have access to a pic or a PET diagram as to what lies underneath?
Thanks.

Landseer

Tank assy:

Landseer

And piping.

As I recall, little beneath the actual cradle triangle.

atb

Thanks for the quick response.
If if makes a difference, this is for the OB track car ('79), not my S4. It looks like the plate is shaped to allow clearance for fittings at the bottom of the tank, but I don't see anything in your diagram.

svpmx83

either the hose marked 20 or the pickup screen/intank pump marked 1,2 and 3

Mrmerlin

if your getting a leak under the tank the most likely contributors are
a loose check valve ,
the 3 sealing washers
and a crushed hard line from the pump outlet to the filter.

Usually the sealing washers are reused, they work harden then wont seal properly.
Then the cap nut is overtightened to try to seal the washers,
then the end of the hard line crushes and deforms enough to cause a leak that can only be fixed by replacement of the hard line and washers..
If your going to have to replace any of these parts sealing washers or hard line i suggest to also replace the check valve,
Put some PTFE sealant on the threads of the check valve then some anti seize on the cap nut.
Work on the whole assembly after removing the fuel pump filter from the car,
dont over tighten the wire nuts they can strip off the studs.

Also less of a chance is that the fuel strainer or internal fuel pump if you have one can develop a leak where the metal collar in the tank is damaged from removal of an old part

geneburda

Adam,
I had a leak in the same place some time ago, turned out to be a hair line crack in the tank itself. Looked to me like the bottom support pan and straps caused a pressure point on the tank which stressed the plastic and caused the crack. I was able to repair the tank with "Seal All" which is available at hardware and home stores.
I did have a spare used tank that someone had give me, and I did install that tank after several month with no problems with the repair.

atb

Sounds like no time trials for me this weekend.

Stromius

I bought the crush washers at the local VW dealer. Per PET they are 12 x 16 - 2 needed.

Mrmerlin

actually there are 3 sealing washers but if the check valve is tight and not leaking then you only need 2

Tom. M

If you noticed..my track car is doing the same...mine is coming from the in-tank filter.. I tightened it just a bit and it slowed..but I was hesitant to do too much ...didn't want to pull the metal ring out of the plastic tank.

Put it up in the air and drop the straps...should be obvious where the leak is coming from..

atb

I had it up on the lift last night, but not enough time to do anything about it.
I was hoping to see an easy way to tie the gas tank up to the body so I could release the straps and see what was going on, but it looks like the tank will need to be supported from underneath unless someone else has a tried and true method.
Maybe some late night wrenching if I can get away.

Tom. M

Depends on how much fuel is in the tank... I was able to loosen the two back straps and the tank stayed in place....enough for me to tighten the in-tank fitting..and then bolt the straps back up...

Maybe a strategically placed 2x4 to hold the tank up..?...

atb

Well, got lucky and unlucky.
Lucky in that the leak turned out to be a very small split in the fuel line on the output barb of the fuel pump. Just cut out the split and used a new proper sized hose clamp.

Unlucky is that while the car was up in the air, I noticed that the alternator belt tensioning bracket had taken a hit. Unbolted the bracket from the bottom of the alternator, and when I went to unbolt it from the block saw that the bottom half of the boss was missing from the block.

Mrmerlin

get some JB weld and get a longer bolt with threads,
cut off the head and JB weld the bolt into the block let it cure then put the bracket over the stud .
Other option get a welder and weld the bottom surround onto the girdle retap (then JB weld a stud into the hole this would be the strongest repair)