Hi! The other day, I noticed this foamy goop inside my oil cap.
I sniffed it and got the strong odor of gasoline!
After a quick search online, I located this excellent write-up, Gas in the Oil, on Rob and Dave's Aircooled Volkswagen Pages.
Apparently, the most likely cause is that the rubber diaphragm in the fuel pump is cracked. This crack lets fuel leak down through the connection from the pump to the engine into the oil. Engine oil mixed with gasoline is not thick enough to protect your engine. So fixing this problem should be a high priority.
Note: The pump works a lot like a bicycle pump: The engine moves a shaft (like your leg) up and down; the pushes presses up and down the spring-loaded diaphragm inside the pump; the pressure of the pump moves fuel up through the filter into your carburetor.
I hypothesize that this crack has several causes: mechanical wear over time, elevated temperatures, and back-pressure from dirty fuel filters. Above, you can see that the fuel level inside the filter is a bit high, and dirt is visible in the folds of the paper.
Ordering the Correct Pump
Looking online, I can see the correct model of fuel pump for my '72 SuperBeetle. However, I'm not sure my car has the stock engine for that year and model. The previous owner said the owner before him had made modifications to the engine.
To avoid mistakes, I'm going to see if the fuel pump on my car displays a part number. From the outside, I don't see any part numbers. So I use a 13mm wrench to loosen and remove the two bolts holding down the pump. (First, I use the standard wrench shown here, but then I switch to the better took, a 13mm socket wrench, not shown)
The following image shows what you see on top of the engine after you remove the pump and the paper gasket: You see a little camshaft sticking out of the engine and some indentations with oil in them. I poked my finger in this oil then sniffed my finger - still the smell of gasoline.
Note to self for next time I do this: At this point, I should still have the fuel lines connected to the pump so I can push the flange and see if any gas comes squirting out the bottom of the pump. Instead, this time, I loosened the O-clamps and removed the fuel lines.
Removing the fuel lines caused a small amount of gasoline to spill on my hands. (This is a severe fire hazard. It's tough to put out a gasoline fire while your hands are burning.) I corked the fuel line from the tank with a wooden pencil.
Note to self: Do this repair with a nearly empty tank next time. Have a friend standing by with the fire extinguisher. Don't allow any ignition sources nearby, such as flames, electrical motors, or electrostatic sparks due to cold-dry weather. Use protective gloves. Gasoline is bad for you. I decided to not pinch the fuel line from the tank with a pair of pliers because doing so was likely to crack the rubber in the hose.
The following image shows the underside of the pump (part# 113127025D). You can see a flange, what I'll call the "pedal", that the camshaft pushes on. According to JBugs.com, this model of the pump has a short flange. If I were using an alternator instead of a generator, I would order a different model of the pump with a longer flange.
Here's an image of the pump laying on a towel. You can also see the paper gasket, bolts, and washers. This conclusively proves that the part I'm looking at online is the right one (pump with short flange).
While I'm in there, I replace the filter with a new one I have on hand (not shown). I bolt everything back together and, now that the gasoline has dried up, start up the engine. Everything runs fine.
I put away my tools and go inside to order the new pump. Unfortunately, although I like and recommend JBugs, they charge shipping for orders under $100. Feeling a little guilty, I order the same part with free shipping from eBay. I also order a pack of fuel filters and some replacement fuel hose.
When it arrives, I'll take pictures and show you how I replaced the fuel pump.
If you enjoyed this content, please upvote and follow. I welcome all of your comments and questions.