Diesel smell after braking

[SSteve]

Once stopped after a moderate to hard brake, the dash air delivers a strong raw diesel fuel smell into the coach. It is in the front of the coach only and dissipates after a minute or two when the coach is moving again.

Once, DW was following in the TOAD and said she could smell it as she passed through where the coach had been.

There is never a fuel odor at any other time.

Looking for leaks, I've checked the left and right fuel caps, filler and vent piping both at the tank and at the fill ports and the fuel lines to the engine and generator. The only thing I can find is a light oily residue around the seal for the generator fuel/oil filter access panel, but no obvious source. It could just as easily be oil as fuel.

Anyone see (smell) this before?

Cat C7, Onan 7500

Steve

[powerboatr]

i will go out on a limb and say after a hard braking you might just be sloshing fuel out of the vents or through a leaking fuel cap, doe sit do it with a full bag of fuel or always no matter the fuel load

[SSteve]

Good question on the fuel level. Alas, I don't have a good answer.

Right now, we're at about 5/8 full and it does it, can't swear to the tank level at other times. It has, however, become a predictable event.

Except for the gen filter access cover, I can find no evidence (wet, staining, disturbed dirt, etc.) to show me where the fuel is coming from.

Steve

[Flagelpater]

Have your DW follow you while you do the same level of braking and look to see if the exhaust is excessively black, maybe have someone video it. The diesel may not be reducing fuel flow soon enough. Just a thought.

[autofish]

I get a hot brake smell after hard to moderate braking this could be called a diesel smell this is ok. If you have a diesel fuel leak it will be easy to spot as fuel is oily and shows up as a wet oil look so just look under the rig to see if is a leak. My bet is it is just brake smell...............good luck.

[HobbyJack]

I have had that smell under hard braking.

[SSteve]

Time for an update.

The Bounder has sat, miserably in it's spot since we returned in late May. No real opportunities to further investigate the diesel smell issue.

Took the Bounder to the dealer for an oil change and chassis lube before heading out again. Didn't smell the smell on the way. Dealer called the next day to say the right side differential seal (at the wheels) was leaking. Freightliner covered the repair (THANKS FREIGHTLINER!!) and we picked up the Bounder the next day.

No smell on the way home! A week later, we loaded the beast and headed out. In the next 4500 miles, we smelled (or thought we smelled) the smell only once. We also had a few opportunities to smell the "hot brake" odor. Very, very different from what we smelled earlier.

So, I can unequivocally confirm that MAYBE the leaking rear seal was the cause and that burning lubricants can lead the unwary into thinking fuel is on the escape. It seems a fair bet.

Keep your smeller in tune.

Steve

[autofish]

Thanks for the up date. Glad to hear they found the cause. Had a ford truck with the same axle leak back in 1989 not only did it smell but make lots of smoke on hard braking till fixed.