Air bubbles in Injection pump feed line...

[Jettagli16v]

Jeez, guys....

I feel like I treat you like an ex-girlfriend!!
I never talk to you guys when my cars are running well, and as soon as I have a problem, I call you, beggin you to take me back!

Anyways,
Working on a new one, 1981 Rabbit Pickup..
I am seeing a constant trickle of air bubbles in the clear plastic line going to my Inj pump.

I know it is a suction side air leak,
likely caused my (mostly) original fuel lines...

Is there a good way to find which line is leaking?

I thought I should saturate the rubber lines with water, one at a time, with the car running, to see when the bubbles went away. (I am a swimming pool guy and that is what we do to find air on the suction side of the pump)
But then I thought, I really don't want to put water in my fuel, especially after the water seperator...

Is there something safe (Veg oil is too hard on rubber, maybe WD-40, or ATF?)
I can apply to the lines to see if I can find my air leak?

or is there a better way? Pressurize the system and look for a leak?

I know I really should replace all the lines, but of course, I am trying to be cheap and direct!

Thanks in advance!
-Brad

[meanvw]

I had that problem with bubbles while running.  Replacing fuel filter fixed it.  All my lines were new/tight.
Can't explain why... But it fixed it.

[Mark(The Miser)UK]

Grease the joints one at a time, or flex  them to make it worse

[jb86]

I fired up my newly rebuilt 1.6 td on Sunday
The clear vinyl line would fill up with air but increased throttle would keep it running
Starting at the tank to the water drain I replaced all rubber fuel line with new diesel line
Parker push loc for 1/4" and marine diesel (low permeation) for 5/16"
Clamped all tight
I temporarily installed an electric lift pump at the fuel tank
That kept the line full of fuel
I'm wondering if the line - filter to IP could leak at the copper crush washer
I don't know a torque rating so I just made them as tight as I dared
I figured I could pressure test with air
Plug the return line coming from IP
Then the line that returns to the tank, install a barb fitting with a Schrader valve and put maybe 10psi into that and see if air bubbles come out some where
Jon

[ORCoaster]

When removing the copper washers from the filter, IP or anywhere on the IP I inspect them carefully and if needed I smooth them out using some diesel on 600 grit wet rub sandpaper in a figure eight pattern.  Then I get a torch and heat them up till they are blue, holding them with a pair of needle nosed pliers.  Then I re-install and tighten back down real good.  Read heavy torque.

[92EcoDiesel Jetta]

Torque the copper washers just enough so it does not leak. You do not want to over torque them if they don't seal, use a new washer instead. The banjo fittings are plated brass or bronze and will crack if over torqued.

[Jettagli16v]

So,
it seems like the short answer is: not so much....

The filter is new,
I have been through a few while getting this thing running.

I do worry about the integrity of my copper washers,
but have had a difficult time finding them in town.
Any advice here?

-Brad

[jb86]

I measured all of the sizes of the copper washers
I found 4 sizes - banjo fittings on filter head - old rabbit style filter (cheaper than mk2 filters) are 19mm head bolt, bolt on IP are 17mm, the air bleeder screw is 8mm, then the timing plug was 6mm, as I recall
I googled and found grainger.com has all of the sizes in 25pkgs for about $5-$8 pkg
Enough for quite a while
Not much available locally
Other than going to dealer
So
They're all new
Concern I had with torque is how much to avoid over torque and damage a thread in the IP or other
I couldn't find torque specs in bentley
I'm out of town for a few days
When I get back I'll try what I mentioned to pressurize from the return line
At that point if pressure drops I can drop some diesel on the lines and look for bubbles
Hopefully
Jon