Tuesday, December 12, 2006

VW - How to Cook a VW Bus

I thought I'd seen/heard every way there was to set your bus on fire. Wrong.

A local fellow (near Vista, California) managed to do it by overhauling his carb.

After rebuilding the carb he fired it up to adjust the idle. Left the air cleaner off. He said it didn't want to start but finally did, running kinda funny, as if a plug wire had come loose. That's when he saw the smoke. Shut off the engine but the thing was burning pretty good by then.

No fire extinguisher of course. He had one but it was buried under a lot of stuff in the back of the bus and the bus was in the garage and he was on the opposite side and besides, there was a garden hose just beside the garage door.

If you drive an air cooled VW a fire extinguisher is some of the smartest money you can spend. If you drive a bus, you need two of the things, one located in the cockpit where the driver can grab it as they jump out, the other in the cargo bay.

He used the garden hose. Worked, but only because there wasn't a pool of gasoline
under the bus.

Hell of a mess. The rear portion of the air seal was fried, along with the fan belt and most of the wiring. But it wasn't quite as bad as it looked. Had to drop the engine so he could replace the air seal. I went over and helped him with the wiring.

The cause of the fire was a mystery. And he'd already figured out that it would be plain crazy to put the engine back in without knowing why it had caught fire.

The only clue I considered significant was that the gasoline had sprayed all over the top of the engine compartment. I thought the fuel hose had blown off or he'd left out a gasket. But the fuel line was in place. All of the gaskets on the carb were in place and the screws were tight. So maybe it was the fuel pump. Or perhaps he'd used one of the old gaskets by mistake. Old gaskets often break when you remove them, leaving a gap for the fuel to escape. The
overhaul kit was still on the bench along with the old gaskets. And two float valves, the old one he removed from the carb before soaking it in carb cleaner, and the new one he forgot to install. Mystery solved.

The float bowl is vented to the atmosphere. On the Solex the vent is a metal pipe about a quarter-inch in diameter that points into the open throat of the carb at an angle. With no float valve installed, once the fuel pump filled the bowl the vent acted as a nozzle, squirting gasoline out of the carb (no air cleaner), onto the ceiling of the engine compartment and from there, all over the engine compartment.

Distributor cap was still in place so the initial ignition point was probably the generator brushes, which create sparks during normal operation.

The Boot Camp of Reality is coming to grips with our own fallibility. Alas, it's a lesson most fail to learn. Once you accept the fact that errors are human and therefore normal, you make it a habit to write things down, to measure twice before cutting, to use lay-out boards when assembling an engine, to use check-off lists before take-off and so on. Not very kewl of course but totally professional.

Education is usually expensive. This lesson was a bargain. He's still got his bus. And his house.

-Bob Hoover

PS - I stole the pictures from the internet. The one at the top is from www.ratwell.com, the one above is from Australia

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