Diesel fuel leak

In February a local garge replaced the fuel filter on my good-running 2005 VW Gulf diesel & caused a leak. They blamed it on cracking a valve & replaced the valve. Ever since then I’ve gotten a quick puff of fuel smell when starting the cold engine, or when taking off from a light or after parking the warm car, shopping for an hour & starting it again. It didn’t always happen, tho, & would disappear instantly. Since warm weather came & I have had windows down, noted fuel odor coming in the front-passenger window while driving & is sometimes noticeable in the car now while driving, windows closed, no fan or AC on. Local garage & VW mechanics can’t find source. No puddles on ground, no apparent leaks inside engine compartment. Fuel MPG down from 50s to 40s. Car never smelled of anything before fuel filter was changed. Still runs smoothly. Any ideas from anyone out there in cyberland?

Diesel only needs a very small leak to pong very badly. And small leaks can be very difficult to detect.

Your best bet is clean all the fuel pipework with a rag, get hold of some talcum powder and dose around all of the fuel pipe unions. You’ll soon see if you have a leak and where it is. The drops however small will wash away the talc or discolor it.

The talk will easily wash off once you’re done. In any case you engine bay will smell better unless you can get unscented from Wallgreens.

Generally, if you have a fuel system leak on a diesel you’ll get air in the lines and the motor will shut down.

On thing about diesel is the smell is very difficult to get rid of. If you’ve ever worked on one, you know what I’m talking about. You can wash your hands and smell it the next day. Is it possible the mechanic got into your car with diesel on his clothes and smeared it on the seat or carpet?

Another thing I would look for is a leaking injector. Injectors that leak will generally fill the oil pan with diesel. Pull the dipstick and check the oil. If you have more than you are supposed to, that’s a good indication of a leaking injector.

Fuel mileage drops generally make me suspicious of 3 things: Leaking injector, need new air filter, or need new fuel filter.