[Vwdiesel] Fuel Leak on Engine

[Val Christian]

Mikey,

I was suspicious when you made your first posting that you might have a
fuel line problem.  You really need to nail down the exact source of
your leak.  This could be by degreasing the area with fuel, and then
having someone tap the starter while you watch.

Do NOT overtorque the injectors.  Their looseness would be a breach of the
compression chamber.  If they are leaking, it's because they were disassembled
and not reassembled correctly.  Not likely.

Remember that the injectors are "gasketed" into the combustion chamber with
the dished "heat shields", which should be replaced each time an injector
is removed.  I've reused them, but I try to keep spares around.  When I
buy bulk, they're less than $1 each.  When putting in an injector, I'd
always use a torque wrench.  Also, I'd make certain that you're not
side-loading the injector when tightening.  I've heard more than one tale
of woe about breaking off part of the cylinder head when torquing down
the injector (with socket extension, and torque being non-rotational
on the socket).

I have seen 1.5/1.6 engines where someone overtightened the fuel lines
leading to the injectors (or pump, but usually injectors), and
the compression nut was stripped, causing insufficient seating torque.
This could cause something like what you describe.

I've also seen it where the flare in the fuel distribution (harness) piping
was damaged, causing a leak.

Lastly, I've seen it where the flare fittings just weren't seated right
when they were tightened down, and wiggling each one prior to tightening
caused them to get seated correctly.  This seemed to happen in cases
where the compression fitting was somehow improperly installed, causing
damage to the seating faces of the softer tubing.  Observations support
the theory that perhaps compression nuts were torqued down, where the
flare fitting was up against the side of the compression nut, and the
fitting it was up against (injector pump or injector) cut into the flare
fitting, leaving a "half moon" indentation, which subsequently leaked.

My opinion is that teflon tape is not the way to go.  You don't want any
stuck in an injector, for sure.  But the real problem is that the threads
are not the sealing component...it's the flared tubing and the injector
or pump fitting, and of course, the compression nut.

Let's talk torque for a moment.  I don't have Bentley in front of me...but
I would say that the compression fittings should never be torqued beyond
30 ft/lbs.  My guess is that when I tighten them, I get them between
15 and 20 ft/lbs (calibrated hand [it takes years of doing aircraft
spark plugs]).

The best approach (redundant, redundant) is to nail down the source of
the leak, and then you're just trying to fix one thing.  Otherwise, you can
screw up or break something else in the process.  Not positive motivation
for the amateur mechanic, and expensive to the customer for the professional
mechanic.

Oh, one more source of a similar leak...the fitting on the injector pump.
Yep, on an 84 Rabbit, I recall the lower rear fitting somehow got loose,
perhaps when I took off a compression fitting, and leaked.  Not enough to
prevent things from running, but enough to wash the engine with fine smelling
diesel fuel, which would drain off with grime when I shut down the car.
The solution was to take a deep socket and tighten the one fitting.  I recall
doing it a couple of times, as I was very ginger, and incrementally
tightened things.  As I recall, the torque required to stop the leak
was a bit higher than I really wanted to go.

Let me know if I can help more.  Again, I urge you to get a helper, and
isolate the area where the fuel is leaking out.  Degrease (careful
application of brake cleaner fluid on a cold engine), and then use
paper towels, and inspection mirrors, while someone taps the starter.
If you want, email me, and we can setup a phone call to discuss.

Good luck,

Val




> Hey gang, To bring everyone up to speed, I had a fuel leak from the front s=
> ide of the engine (1.6 NA in a 1982 Rabbit). I wasn't sure of the source so=
>  I tried some different stuff.  1. I cleaned the fuel injector pump mount s=
> ince I know I neglected to do it when I put the engine back together...it w=
> as nasty dirty. 2. I checked all fuel lines (to/from) the pump to ensure th=
> at they were tight and well mounted. Now I know there's still a fuel leak '=
> cause when I try to turn it over to get it to start, it still pours fuel ou=
> t of the engine. Now, it seems to be definitely from the area of the inject=
> ors. Some thoughts/questions. 1. how hard is it ensure that the injectors a=
> re seated properly? Can I just crank them down if they are loose? What type=
>  of seat are they on? 2. how hard is it to ensure that that the fuel lines =
> (stainless steel) are properly tightened on the injectors...they seem to be=
>  on there right, should I put some pipe-dope (teflon tape) on the threads? =
> Any thoughts would be greatly appreciated. Thanks,Mikey