gas smell

[nucor]

i changed my gas filter back about month ago in my 94 e420 i am starting to smell gas near the rear passenger side of the car but there is no leak i dont see gas on ground n gas mileage is real bad now

[86560SEL]

Could be a poor seal on your fuel tank cap.

[tinypanzer]

Not trying to be flip or sarcastic in this response, but you've contradicted yourself. If you're smelling gas then there IS a leak, by definition.

So, if this problem cropped up right after the fuel filter was changed, then that's probably the source of the leak. Compression fittings can be a real pain. Sometimes they just don't want to seal up and you wind up having to polish out whatever blemishes have occurred on the mating surfaces.

Just because you don't see gas on the ground doesn't mean much. Keep in mind that gas evaporates very quickly and I've seen rather substantial leaks that never made it to the ground, they just trickle all over the undercarriage and stink everything up. On bright metal surfaces, the evaporating gas will leave behind a yellow-brown varnish which will have a gas odor. A quick wipe with a cloth followed by a sniff will tell you if that's going on.

If you did the filter yourself, I'd try to re-seal the compression fitting. If you paid to have it done, then take it back, it's under warranty.

The other possibility is that you have an evap/purge issue possibly due to a plugged up charcoal canister or some other tank venting issue. That would possibly explain mileage too, but then so would a leak.

Originally Posted by nucor

i changed my gas filter back about month ago in my 94 e420 i am starting to smell gas near the rear passenger side of the car but there is no leak i dont see gas on ground n gas mileage is real bad now

[big dog 2]

I had the same problem for awhile! There were no leaks until one day the gas smell got worse (along with the gas mileage) and a small puddle of gas appeared below the car where the filter was. Turned out the rubber hose from the fuel filter to the metal fuel line had a small crack in it and it got worse over time. I ordered a new hose online for about $25. It is a hose with a custom fitting on it that attaches to the fuel filter. It was simple to replace!

[dhjenkins]

No puddle does not equal no leak as fuel evaporates quickly.

Recheck your fittings & hoses. Apply some yellow teflon tape just in case.

If your rubber hoses are hard, replace them.

[gsxr]

Any update and/or solution?

[stevenstevensteven]

Originally Posted by dhjenkins

No puddle does not equal no leak as fuel evaporates quickly.

Recheck your fittings & hoses. Apply some yellow teflon tape just in case.

If your rubber hoses are hard, replace them.

I've got a similar problem, which I've also had in the past with my compression fittings. I've not tried the yellow teflon tape before, is that a common fix for sealing these compression fittings?

I was thinking about trying some of the blue locktite I have. Is that an acceptable option?

[Rob Pruijt]

I always put a little grease on the compression fittings, they seal more easily that way.

Rob

[stevenstevensteven]

Originally Posted by Rob Pruijt

I always put a little grease on the compression fittings, they seal more easily that way.

Rob

Actually, I just did some poking around on the web and the following Permatex product was suggested for automotive flare nut applications.

http://www.permatex.com/products/Automotive/thread_compounds/a_thread_sealants/auto_Permatex_High_Performance_Thread_Sealant.htm

Any comments on this product?

[Ferdman]

nucor, closely examine the rubber fuel lines in the vicinity of the fuel pump with the engine running. I recently replaced the rubber fuel lines on our 1995 E320 because they were leaking. The fuel lines utilized hose clamps on both ends, as opposed to compression fittings, so check what style fuel lines are on your car before purchasing any replacement parts. Purchased replacement fuel line at our local MB dealer and reused the hose clamps.

[86560SEL]

I was going to give you Barney Fifes answer to this....

In a high agitated voice....
"Of course you smell gas, what do you think this car runs on, coal"?

LOL. Sorry, could not resist.

[Rob Pruijt]

Originally Posted by stevenstevensteven

Actually, I just did some poking around on the web and the following Permatex product was suggested for automotive flare nut applications.

http://www.permatex.com/products/Automotive/thread_compounds/a_thread_sealants/auto_Permatex_High_Performance_Thread_Sealant.htm

Any comments on this product?

Compression fittings do not seal on the treads, the grease is just to make it seat more easy.

Rob

[stevenstevensteven]

Originally Posted by Rob Pruijt

I always put a little grease on the compression fittings, they seal more easily that way.

Rob

Originally Posted by Rob Pruijt

Compression fittings do not seal on the treads, the grease is just to make it seat more easy.

Rob

Rob, I'm a little confused. So you do NOT put the grease on the threads of the flare nut?




When then do you apply the grease, on the tapered portion of the nut? If yes, does this simply help create a barrier/seal when the flare nut is compressed onto the end of the metal hose? If placing the grease on the tapered portion, do I not need to concern myself with getting grease inside the fuel system and fouling the injectors?

Thanks.

[Rob Pruijt]

Not on the treads just a little bit on the mating surfaces.

The grease can not get in the fuel system, the pressure is in the other direction.

Rob

[WaBenzer]

As an aircraft mechanic, when in the field without resources, I've found that most flare fittings *except oxygen lines fire hazard* I can rub my clean fingers on the crease between my nose and cheek. Or, rub my forehead and wipe my fingers on the flare surfaces. The film helps the metals slide to seat when tightening. The threads may need a little too. Because the threads are supposed to be dry, sometimes the lines just won't line up good enough to start threading without a little help.