Sunday, December 24, 2006

VW - TULZ Part Six


TULZ – Part Six

FIRE!

Gotta fire extinguisher? No? Howzabout a bag of marshmallows? Cuz if you own a Volkswagen you really should carry one or the other. Your choice.

On average, it takes a 15 lb dry-type fire extinguisher to snuff an engine fire on a Volkswagen. That's assuming you know what you're doing and jump right on it. Assuming you've got one on-board. And can get to it. Bus owners should carry two, one reachable from the driver's seat, the other from the cargo-bay door. Jump on it quick and the damage can be limited to the wiring, fan belt and hoses. But if you dawdle the fire will ignite the magnesium crankcase and tranny. Ever tried to put out a magnesium fire?

Come to think of it, have you EVER used a fire extinguisher? Old sailors like me know how; firefighting and damage control is part of Navy boot camp. (Why? Cuz you can't walk home.) If you've never donated eyebrows to the Maltese Cross it wouldn't hurt to check with your local Fire Department. Most of them will be happy to show you how tackle a gasoline fire. There's a bit more to it than Point & Shoot.

(Funny-Sad Stories: Woman's westy catches fire. No problem, she has a big extinguisher. Lugs it around to the smoking vent… and finds she can't pull the pin, unaware that particular extinguisher requires the handle to be partially depressed to allow the pin to pull free. Marshmallow event. Similar but different case: Plumber in his service truck sees a VW bug smoking on the side of the road, pulls up to help. Discovers the safety pin on his extinguisher has had the end peened over. Has to find a pair of pliers to free the pin, by which time it was too late to do much good.)

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Volkswagens like to catch fire, mostly because of you; because of the things you do and because of things you don't.

A fire stands on three legs, fuel, air and a source of ignition. Chop off any one of those legs and you don't have a fire. With a car, you can't do much about the air or the source of ignition so you focus on the fuel, the gasoline.

Pound for pound, gasoline has more potential energy than dynamite. Toss a kid a two-pound stick of 20% Hercules and he's liable to crap his pants. But give him an even more dangerous quart of gasoline and watch the foolishness begin.

Here's a good example. See that cute little fuel filter? The one between the fuel pump and the carb? You probably paid about two bucks for it even though it only cost a nickel, wholesale. When you installed it you thought you were doing your ride a favor but the truth is, those two bucks can cause your Volkswagen to catch fire. Herez how: The added mass of that little filter, combined with the normal vibrations produced by the engine and the surface of the road, is enough to loosen the brass ferules in your carb and fuel pump as the hose wiggles up & down. And once they come loose, they pop out. The engine keeps right on running of course – there's plenty of fuel left in the carb. And so long as the engine is running, so is the fuel pump. The gasoline gets sprayed all over the engine compartment and is ignited by the sparks from the generator or the distributor (there's plenty of sparking going on inside your distributor and it's open to the atmosphere).

That little fuel filter can be the dumbest two bucks you'll ever spend.

Volkswagen provided your fuel system with a strainer in the fuel tank and a fine-mesh filter – finer than any orifice in your carb – in your fuel pump. When they went to the non-rebuildable pump they put the filter under the fuel tank.

The filter in your pump is supposed to be cleaned every three thousand miles. Nobody does, of course. Too much work or something. Instead, they buy one of those kewl two-dollar filters that everybody sez is such a smart idea. The only smarts in this equation is the 2000% mark-up on that crappy little filter :-)

So why'd folks start putting filters between the pump & carb? Because either the gas tank or the fuel pipe was starting to rust. The VW is a cheaply built car, the fuel tank is made of plain carbon steel. It loves to rust. When it does, you don't add filters, you deal with the rust. You pull the fuel tank, etch it with acid then slosh it with PVA sealant. Bingo! No more rust. Or you replace the fuel pipe. Or both. (See the real Volkswagen Workshop Manual for the repair procedures.) [Roland Wilhelmy replaced the fuel pipe in the tunnel of his '57 with a single piece of stainless steel tubing. He put threaded fittings on either end. Neatest bit of plumbing I've ever seen on a bug.]

The punch line to the joke is that lotsa kiddies will spend thousands of dollars getting rid of the rust on the OUTSIDE of their Volkswagen but ignore the cancer in their fuel tank, even though they know it's there. That's why the bought the filter, right? (And if you haven't figured it out by now 'kiddie' has nothing to do with age. It has to do with acting in a childish or immature manner.)

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So you check the brass ferules on your fuel pump & carb and, big surprise, they're loose. Now what?

The best fix is to replace them with threaded fittings. There is some aircraft stuff that is small enough to fit the casting yet provides adequate flow.

Or you can knurl the ferules and reinstall them with a dot of sleeve retainer. And then safety the hose. Herez how.

To knurl the brass tube you use a mill-cut file as a knurling tool. ( A mill- cut file has just one row of teeth across the face of the file.) You put the brass ferule on a piece of smooth wood then press the file down on top of the brass tube then ROLL the tube by pushing on the file. The teeth of the file will EMBOSS grooves in the brass and in doing so, increase the OD of the ferule. Making it larger in diameter makes it fit tighter in the casting. (No grooves? Press harder. The hardened teeth of the file WILL emboss the softer brass. Just be sure to use a block of hard wood, leather or plastic for the 'anvil' on which you do the rolling. If you roll it

on metal, the metal will simply flatten the grooves out again, as fast as you make them.)

So go clean the casting (ie, the carb or the fuel pump). Chuck something into your Makita, put a wisp of fine steel wool on the tip and polish the bore in the casting. When it's shiny, swab it out with MEK and a Q-tip. Now the sleeve retainer will bond to the pot-metal casting.

Got your sleeve retainer? Sleeve retainer is high-strength loctite, the green stuff. Use MEK to clean the ferule you've just knurled, put a dot of sleeve retainer on the knurled part and drive that sucker into the bore with a well aimed tap of a hammer. Then let it cure for 25 hours. 24 if you're in a rush.

Install the fuel hose with clamps on both ends. To safety the hose, use light-gauge safety wire, the same stuff you use to safety the set-screw on the shifter-rod (I think it's .028; mebbe .016. Either size is commonly available. See the Harbor Freight catalog.) Make a double wrap around the hose BEHIND the clamp then secure the wire to the carb or fuel pump. Now even if something comes loose, the worst it can do is leak; it can't blow off and spray gasoline all over the engine.

The other common cause of engine fires is due to your failure to replace the grommet isolating the fuel pipe where it passes through the forward breast tin.

Back in the good old days, whenever that was, every time you took your Volkswagen in for service they'd check the grommet. (You check it with your thumbnail.) If it was hard, they'd replace it. And it got hard pretty quick since it's only inches away from the #3 exhaust stack, which runs red hot at highway speed. The rubber grommet soaks up the radiant heat from the cherry-red steel and cooks itself harder than a bride's biscuits in no time at all.

Once the grommet gets hard it cracks into pieces and falls out, leaving your fuel pipe to rub against the .025 edge of the sheet metal of the forward breast tin. Now, you wouldn't think a piece of sheet metal would make a very good saw but remember, it only has to cut far enough to let the fuel spray out. And that don't take long at all. So now you got raw gasoline dribbling out the fuel pipe just inches from the #3 exhaust stack.

See why you need to carry those marshmallows? No sense letting a good bonfire go to waste :-)

So what to do? You can just keep putting grommets in the hole but that's sorta lame. It was okay back then; cheap car, inexpensive service, only takes a few minutes to replace the grommet. And so long as you had the vehicle serviced by the dealer there was never a problem. But times change. Nowadays, the whiz kid at the local quickie lube emporium wouldn't recognize a grommet if it ran up and pee'd on his leg. And even if he did, he'd want a zillion dollars to replace it, being a highly trained technician and all.

So you install a bulkhead fitting, which actually isn't. Bulkhead fittings are threaded on both sides. What you'll make up looks kinda like a bulkhead fitting but it's actually a 'pass-through'. Easy to make. Cost you mebbe two bucks. No more grommet, no more fuel-pipe failure and no more fuel-pipe-related fires. You can leave the marshmallows at home. (But keep the extinguisher in the car. Shit happens.)

To make your bulkhead fitting you begin with a piece of Volkswagen fuel pipe, three inches long. Quarter-inch tubing (that is, non-metric SAE stuff) is a little bit too large for the stock VW fuel hose but a SAE brake line stock, which is available from most FLAPS, is close enough to work.

The three-inch long piece of fuel pipe must chamfered on the ID at both ends and then the ends must be carefully smoothed with #600 paper. Finally, you need the flare the ends just a tad to create a SMALL lip to secure the hose. Be careful here. Small means exactly that. You can feel the flared lip but it isn't obvious to the eye. The important thing is that the hose will feel it too.

The other parts for the bulkhead fitting are down at your local hardware store, hanging on the rack with the other ELECTRICAL repair parts. Ask for 'lamp repair parts.' A common brand-name 'Angelo' (ie, Angelo Brothers Co., from Philadelphia). You want a threaded barrel one-inch long. It will probably come in a blister-pack with an assortment of barrels of other lengths. The 1/8-IP thread is standard for all lamp stuff so don't worry about it; lamp nuts fit on lamp barrels.

Once you have the barrel you need two nuts to fit it. They'll be hanging on the same rack. If they have internal-tooth lockwashers for the nuts, get some.

The other part of the kit is a pair of fender washers having an ID large enough to accept the threaded barrel.

Lamp hardware comes in both brass and steel. Brass will work but the steel stuff is stronger. If you live in the rust belt, brass might be a better

choice. I assume you'll paint the steel stuff.

To assemble the pass-through you want to bed the piece of fuel pipe in the threaded barrel. To do this, insert the fuel pipe into the barrel for about an inch then slather RTV on the exposed fuel pipe for a distance of about an inch. Now insert the slathered fuel pipe into the barrel using a twisting motion. You want to end up with an inch of fuel pipe projecting from each end of the threaded barrel and the fuel pipe firmly bedded in RTV inside of the barrel. Once you've achieved that, put the thing aside to cure.

To install the pass through you spin a washer (and lockwasher, if you have it) onto the barrel, about half-way down. Then slide a fender washer onto the threaded barrel so it comes up against the nut (or lockwasher).

The object is to insert the threaded barrel through the hole in the forward breast tin and form a sandwich of fender washer – breast-tin – fender washer, secured by nuts on either side. That's the goal. And it works. But the first few of these I made, the nuts came loose. I used lockwashers and even two nuts on each side but given the heat from the exhaust stack and the vibration, the things eventually loosened up.

So I glued it together. I used some high-temp (red) RTV and liberally buttered the washers & nuts before tightening the thing down. That was in 1981. It's still tight. So use the RTV trick to keep it from coming loose.

Stock VW fuel hose will push over the SLIGHTLY flared ends of the fuel pipe. You should then install hose clamps but do so LIGHTLY. You don't have to tighten a hose-clamp very much. The combination of the clamp and the small flare effectively locks the hose to the pipe.

There are some details here you should be aware of. The old fuel pipe will need to be shortened. I use the stock bracket on the end of the blower housing to secure the stock fuel pipe. On some vehicles the bulkhead fitting can be difficult to install with the engine in the vehicle. I

think it's a mod worth dropping the engine for but then, I drop the engine just to wash the engine compartment.

One thing you should do IMMEDIATELY is go out to your car and check that damn grommet. IF it is hard or missing, replace it NOW. A quick but TEMPORARY fix is to slit a section of suitably sized hose, clip it around the fuel pipe, slide it into the hole in the breast tin and slather it with high- temp RTV. In theory, that should work at least as well as the grommet and maybe as well as the bulkhead fitting. But in practice, the thing tends to come adrift, possibly because it gets gasoline on the RTV or mebbe from the heat or… something. The metal barrel works best. But you're the Mechanic-in-Charge. Your ride; your decision.

The grommet problem isn't new. It was first identified as a cause of Volkswagen engine fires about 1958. In the 1960's I used aviation-grade bulkhead fittings on my Volkswagens, replacing all of the stock fuel plumbing with higher quality aviation stuff. That's when I was working for Uncle Sam and he didn't mind if his nephews diddled the system a little, so long as the planes didn't fall out of the sky. Not too long after leaving the Navy I needed a bulkhead fitting, saw how much the silly things cost and came up the lamp-parts arrangement as a substitute. It works.

-Bob Hoover
-20 April 2K

1 comment:

Jeff Boatright said...

On fire extinguishers and things that can go wrong with them, I was at a Road Atlanta and saw a car totally gutted by fire because the extinguisher pin was "safetied" with a zip tie (NOT the little, skinny, easy-to-break plastic ring that they are sold with). When the corner worker couldn't pull the pin, the driver snatched the extinguisher from him. When HE couldn't pull the pin, he just through the damned thing through the (now melted) windshield and stalked off screaming and waving his fists at the safety tower. I've always wondered about the brain power it took to safety an extinguisher pin with a tie wrap the size that police use as quickie handcuffs...

As to always having an extinguisher on board, it's good for even more than just your protection. Back in our high school daze, my brother was driving himself and his date to dinner when the car stopped in front of them at the light caught fire. My bro nonchalantly got out, pulled the extinguisher from the trunk, and calmly extinguished the fire. His date was so impressed with that "James Bond" attitude and action that he got to run the bases that night. Or so HE says... :)

So, practice safe sex, but watch how you "safety" your pins!