Gas Engine Fuel Smells in Car

This one you definitely do not want to ignore!

A few days ago I fired up my 1971 300SEL 3.5. Within a minute after start up I could pick up a faint smell of gasoline fumes. I immediately shut the engine down. I learned a long time ago flying airplanes you don't ignore fuel smells or strange noises. I looked under the car and could see fuel dripping down the back of the engine block and onto the garage floor. Without even opening up the hood I had a pretty good idea what I was going to find.

Problem & Solution

Common among these chassis:

Classic Sedans
W108 W109
W110 W111 W112 Sedan
W111 W112 Coupe


Sure enough it was a leaking braided fuel hose (and I had even replaced these about 5 years ago). This is a very common problem on older gasoline engines and has led to many engine fires. If you smell fuel DONT drive the car. Find the source of the smell immediately. 8 out of 10 times expect to find a leaking fuel hose. 

I hate braided fuel hose on both gas and diesel engines. It tends to deteriorate and weep out the the braided covering. I no longer use it. I replace all fuel hoses with high quality rubber reinforced hose. In the case of my 3.5 I replaced the braided hose with a high pressure fuel injection hose used on older BMW's. 

This is a good example of why I no longer use braided fuel hose.