Gasoline Filtering

This article was contributed by Jay Salser who is a reader of 1967beetle.com. Where to place a fuel filter in an air-cooled engine has always been the topic of heated debate. I personally do not run mine in the engine area, nor do I recommend it. However, I do see the value in a good argument. Jay makes some good points from his own experiences that are worth sharing. Where do you place your own fuel filter? Feel free to join the conversation at the bottom of this article.

A Short Discussion on the Filtering of Gasoline for VW Engines

It was the early ‘80s and I awakened one day to find that my ’67 Beetle would not start and run. “What?” I thought. At the time, we had 3 other VWs—two more Beetles and a ’67 Karmann Ghia—all running, driving, registered, inspected and insured.

That day, I didn’t go to work. Instead, I opened the carburetor and found gunk! Pure gunk! Upon inspection of the 3 other vehicles, I found a similar situation. There was nothing to do but to bite the bullet, tear into the carbs and clean the gas tanks. I did all of this that day.

Subsequently, I went to the gas station that we patronized and accused them of having dirty gas. They asked to see the receipt for the carb kits and promptly paid. But, they wouldn’t pay me for my labor.

I installed a fuel filter in each car.

A few days later, my wife was at that same gas station and happened to look at the pump. To her surprise, a notice was posted there: Contains Ethanol. Aha! The culprit.

The Ethanol had absorbed moisture in the tanks, along with any debris there and had carried everything to my unfiltered carbs. We switched gas station companies. It was a couple of years before that station chain began using Ethanol. Nevertheless, I had learned my lesson. I became a champion of fuel filters!

Since then, I have had a fuel filter in every VW that I have owned and driven.

I place them in the engine compartment where they can be regularly observed. There is nothing like being able to have an easy window to assess one’s fuel supply. I have heard of people who place the filter beneath the car and forget it. Out of sight, out of mind.

I hasten to admit that having the filter in the engine compartment is unsightly, especially in a classically restored car. As well, some worry about the danger of fire, should the filter spring a leak or come loose.

Some place the filter before the fuel pump in the engine compartment. Generally, this has the filter lying on the engine tin. I prefer not to have it on the tin where heat could melt the plastic and/or boil the gasoline, or where friction could wear away the filter housing.

By the way—using a metal bodied filter defeats the advantage of being able to view the filter’s contents. A metal bodied filter should be changed on a regular basis to insure good performance.

My habit has been to install the filter on the “high” side of the pump with a short length of hose from the pump to the filter followed by another short length of hose to the carburetor. This keeps the filter off the tin.

But, I want to speak to the issue of fires in the engine compartment. Of the VW fires which I have observed (and burnt cars), the problem usually comes from 4 sources:

1. The Brass Inlet Tube to the carburetor. These tubes eventually can work loose due to age, vibration and pressure. Anytime I am replacing fuel hose to the carb, I check the brass inlet tube to be certain that it is tight. If I have the carb out of the car, I use a tiny punch to “stake” (gently) around the tube to expand the carb’s metal housing against the tube.

2. Old Hose. We tend to forget how long it has been since fuel lines in the engine compartment were replaced. I tell people to monitor the fuel lines in the engine compartment constantly. It the lines are showing age–at all–including discoloration, fraying, etc., remove and replace! No cutting off the “bad end” and reinstalling–replace!

3. The Wrong Type of Fuel Hose. People WILL go to XYZ Auto Supply and buy any kind of rubber hose and install it into their cars. Use only approved fuel hose—5mm cloth-braided hose with gasoline resistant core. This hose immediately fits the carb and fuel pump tubes and is durable.

4. The Lack of Clamps at the Carburetor, Both Sides of the Fuel Pump and At Other Junctions. Unfortunately, most of us can’t find (or don’t bother to find) the proper clamps (similar to the clamp/squeeze-on original style). We use screw clamps. These should be used carefully, if that’s what’s available. I never clamp a fuel filter. The ends on a fuel filter are large enough so that they will fit snugly into regulation hose and will not come loose. Some people make the mistake of clamping the filter ends–this tends to smash the plastic and can restrict gas flow.

I do not like the look of a filter in the engine bay. It just doesn’t look right. But, we are at a place where we need filters and we need to monitor them on a regular basis. A compromise would be to place the filter beneath the car when showing the car but have it in the engine compartment when driving. Or…to follow Eric Shoemaker’s example: have a white board in the garage where maintenance requirements and servicing can be recorded and seen daily.

Happy Motoring!