Subject: Fire Hazard!: Be sure to also check your hard lines!!
bajachris88
A.k.a.: Chris Leete
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posted on April 12th, 2015 at 11:21 AM
Fire Hazard!: Be sure to also check your hard lines!!
Thought i'd share an experience last week, it might prevent heartache for some.
Long story short, got back from Stradbroke Island in the baja. Over the coming days, a fuel smell, followed by a puddle in the dirt under the engine
bay developed. I didn't plan on driving it that week so no stress.
On inspection, where the hard (steel) fuel line penetrated through a hole in the fire wall, the years of 'rubbing' and vibration through the sheet
metal hole (and it wasn't a sharp edge hole either) resulted in a 'V' groove into the hard fuel line, to the point that it began leaking. drip drip
drip at an alarming rate! Lost a quarter of a tank on the gauge.
and as we know, the fuel line wraps and dangles down past the passenger side ignition leads, past the dissy etc, with plenty risk of spark.
Moral of the story: yes, check your soft lines, but also your hard lines! And rubber grommets are a great idea! If it hadn't been a baja with the
open ventilated engine bay, it could have been far more risky.
The hard line was original vw.
Thanks,
Chris.
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posted on April 12th, 2015 at 02:13 PM
Quote:
Originally
posted by bajachris88
... the hard (steel) fuel line penetrated through a hole in the fire wall, the years of 'rubbing' and vibration through the sheet metal hole (and it
wasn't a sharp edge hole either) resulted in a 'V' groove ...
Chris.
True dat. Here is one of Bob Hoover's famous "sermons" on the subject:
How to Prevent Engine Fires
in
Air Cooled Volkswagens
A trite phrase sprang up in southern California with the introduction of the fuel injected flat fours. "There's only two kinds of Volkswagens: Those
that have had an engine fire and those that are about to." But the odd thing was, veedubs have ALWAYS had engine fires, and in the case of the bugs
and buses, the cause was almost always the same.
In over 90% of early VW engine fires the steel fuel line breaks where it passes through the breast tin on the driver's side of the engine
compartment. The broken line dumps fuel directly onto the neck of the #3 exhaust outlet. The rest is history. Once the fuel line breaks, gravity keeps
the fuel flowing to the fire. When the magnesium tranny housing heats to the point of ignition, even water can't put it out. (That's what's inside
a Thermite grenade.)
Why does the fuel line break? Because of the failure of the rubber grommet where the steel fuel line passes through the forward breast tin. Located
only inches away from the the #3 exhaust stack, which runs red hot, the grommet soon hardens. Vibration does the rest, first crumbling the grommet
then providing the motion that allows the breast tin to cut through the steel tubing like a hacksaw. A dull and toothless hacksaw but one that cuts a
lot faster than you would think. This scenario of component failure and wear is generally known as The Engine Fire Syndrome.
The fix? Make a bulkhead fitting.
You can make a bulkhead fitting that's good enough for the job using lamp repair parts, purchased at a hardware store. The light socket is attached
to the lamp by a piece of threaded 3/8" steel or brass tubing. The threaded tubing is widely available, often sold bubble-packed in an assortment of
lengths. You need a piece about an inch long. Matching nuts are sold the same way, they are usually hanging side-by-side among the other lamp repair
parts. You will also need a pair of flat washers with a 3/8" center hole. Be sure the washers are large enough to cover the hole in the breast tin.
Fender washers work best but you'll have to drill them out to pass the threaded tubing.
Assemble the parts so as to sandwich the breast tin between the two washers. To make sure it doesn't come apart, bed the washers and nuts in
high-temperature RTV compound. It's messy but I've found this is the only assembly method that stands up over the years.
In proper terms, what you end up with isn't a bulkhead fitting but a pass-through. And what you pass through it is a piece of 5mm steel fuel line
(that is, regular VW fuel pipe) about three inches long. Bed this in RTV as you insert it into the threaded sleeve with a twisting motion (but don't
get any in the fuel line). NOW you have a bulkhead fitting. Use regular push-on fuel line (but with clamps, please) to connect to the bulkhead fitting
and you're all done.
The Engine Fire Syndrome was first identified about 1958. Despite frequent fires, VW showed no interest in fixing the problem, insisting the lame
rubber grommet they used was good enough so long as someone inspected/replaced it every 3,000 miles or so(!), which they did, back when there was a VW
dealer in every town and service was cheap.
Making a bulkhead fitting from commonly available parts will prevent a lot of engine fires but the fuel system on early Volkswagens remains a
compromise between safety and cost. Having invested considerable time and money keeping our bugs alive, it seems silly to put that investment at risk
by using push-on fuel lines. Threaded aircraft-type fittings are a better solution; the carb and fuel pump can be modified to accept such fittings.
Using a true bulkhead fitting through the forward breast tin, and braided stainless steel flex lines between there and the carb, will give you the
safest possible installation.
If you're serious about safety and long-term durability, you may wish to carry the fuel line modifications all the way through to the gas tank, even
to replacing the fuel pipe in the center hump with stainless steel tubing. This is best accomplished during a body-off resto. Once things are back
together you'll know your fuel system will never fail.
A neat trick that gets around the difficulties of replacing tubing in the center hump is to run a new 3/8" diameter stainless steel fuel line
EXTERNALLY. It is protected by a piece of 3/4" angle iron welded to the belly pan in the form of a 'V'. A bit of artful grinding and some careful
bending allows the angle iron stock to follow the contours of the belly pan stampings. Tacked and then welded full-length, the modification is strong,
attractive and durable.
I've been working on VWs since 1956 and have seen, personally or in photos, the results of several fires as described above. The cause of the fire
was often overlooked because the steel fuel line appears to be intact. But on cleaning away the fire's residue you'll discover the tube is cut half
through, which for a fuel pipe is as far as you need go to make the juice flow.
posted on April 12th, 2015 at 11:21 AM
