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Diesel smell in basement

I'm still trying to track down the source of the strong smell of diesel in my basement.  I thought for awhile it might be coming from the aqua hot but now I think it's probably coming from the fuel tank area and seeping into the main storage compartment through the cable/fuel line opening.  Both areas smell very strongly of diesel but in the storage compartment the strongest smell is up near the cableway opening.  It's hard to see into the small area above tank, but what I could see/feel is that all the fuel connections that I could reach feel tight and dry except for the one I'm enclosing a picture of.  Don't know exactly what it is but two small fuel lines T together and are secured to the tank with a black gasket and nut.  There is obviously fuel glistening around this nut and gasket.  Don't know how it is secured on the inside of the tank.  If there is another nut on the inside of the tank it looks like the tank would have to come out to replace the gasket. Tried tightening the nut a little and didn't help.
I looked on a 2000 U320 and saw where this connection was welded/soldered on instead of the nut/gasket arrangement so I'm guessing this was not a good design and was changed.
The two photos show it now and the top view of the tank when it was out for fuel line replacement last fall.
Does anyone have any experience with this connection?  Is it normally tight and dry and just needs a new gasket or is this a common problem? 
BJ Holden
'98 U320 36'
Motorcade #16754

Re: Diesel smell in basement

Reply #1 –
Have you checked both connections above the gasketed one?  Clean with brake cleaner and inspect carefully.
Regards,
Brett

'99 42' Foretravel Xtreme
'14 Brown Motorsports Stacker
'05 Chevy SSR
'02 BMW R1150R

Re: Diesel smell in basement

Reply #2 –
Everything above seems to be tight and dry.  Just the nut/washer/gasket area is wet.
BJ Holden
'98 U320 36'
Motorcade #16754

Re: Diesel smell in basement

Reply #3 –
BJ,

The fitting that you have the blue tie wrap on is your fuel supply and return to the aquahot.  On ours there is a gasket on the inside just like you have on the outside.  Is your tank still out? If so just loosen the top swageloc fitting, This will let you loosen the "T" from the bulkhead fitting.  When the "T" is completely loose it can be lifted out along with the fuel pick up line.  The trick to getting the bulkhead fitting out is to fish a piece of wire through the center of the fitting around and back out through the fill neck.  Once this is done then you can unscrew the nut on the bulkhead fitting and be able to get the inside part out without it falling to the bottom of the tank. Now you can replace both gaskets and do all this in reverse and you will be good to go.

If you don't understand I will P/M you my number a so we can talk. We have helped 2 or 3  other members with the exact same problem.

Pamela & Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Diesel smell in basement

Reply #4 –
I'm not sure of this, but once I filled the fuel tank clear to the very top and placed the coach in storage.  When I returned a week later there was fuel spilled all over the place.  Overfilling is the only thing I could come up with.  Has not happened since and I no longer fill the tank full to the top.  The coach is parked under roof, so the only heat that may have caused fuel expansion is the returned fuel from preheater.  Only dorve 1 mile from fuel fill to storage and I filled with 100 of 150 gallons.

Once the fuel dried up inside the compartment, the diesel smell went away.
Peter & Beth Martin
No Forrest? What have you done?
MC# 15890 until Dec 2016; FMCA #F329677
Cincinnati, OH

Re: Diesel smell in basement

Reply #5 –
Peter,

Particularly if this was in the summer and the station tanks were in the ground, this is normal.

Cold fuel filling the tank and them warmed up (exposed to ambient temperatures) EXPANDS. If the tank was full to start with, it will escape from the tank vent.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Diesel smell in basement

Reply #6 –
So maybe it has been assembled wrong and the gasket is supposed to be on the inside?  Or is there supposed to be a gasket on both sides?  And when it is assembled correctly will it actually be tight or is it just a bad design and will always leak a little?
The tank is not out now.  That picture was taken last fall when Bernd was replacing the fuel lines.  I don't think he did anything with that connection itself, just replaced the fuel lines that connect to it.  I'm presuming that the connection and it's gasket are still original from 1998. 
I'm leaving for the Maritimes shortly and am going to Nac enroute.  I'm taking it back to Bernd to do whatever we have to do to fix it and I'm thinking that the tank will have to be slid out again.  If you have done this before I would like to get the details on how you did it and will pass that along to Bernd.
I've had a little fuel smell in the basement storage forever, just wasn't near this bad.  I figured everybody had that.  But maybe this has been oozing for a long time.
I usually do not fill clear to the top, and always try to plan my fuel stops so I burn some off before I bring it home and it sets. 
The smell is really bad and permeates the whole coach.  Don't know if that little leaky connection can explain all that or not but I can't find anything else.
BJ Holden
'98 U320 36'
Motorcade #16754

Re: Diesel smell in basement

Reply #7 –
Where is the vent?
BJ Holden
'98 U320 36'
Motorcade #16754

Re: Diesel smell in basement

Reply #8 –
BJ,

On our coach there was a gasket on both sides.  On some coaches you have enough room to get the fuel pick up line out without removing the tank but that just depends on the location as to where it was put in the tank.

Pamela & Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Diesel smell in basement

Reply #9 –
Have you tried tightening the nut while holding the fitting?  That is what compresses the gaskets and makes for a "diesel tight" seal.  Stop before you deform the gasket.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Diesel smell in basement

Reply #10 –
Yes I did try to tighten it that way.  But when II tightened it just a little bit the edge of the gasket started to lift right away so I think it is about as tight as it reasonably can be.
Is the vent the thing that looks like a gray pipe cap with a white tie wrap around it in the center of the picture that shows the top of the tank?  If so where does the vent line go?  The line that is attached to it disappears toward the center of the coach and I can't follow it.
BJ Holden
'98 U320 36'
Motorcade #16754

Re: Diesel smell in basement

Reply #11 –
Quote from: corndog254 –
Is the vent the thing that looks like a gray pipe cap with a white tie wrap around it in the center of the picture that shows the top of the tank?

 If so where does the vent line go?  The line that is attached to it disappears toward the center of the coach and I can't follow it.
1. Yes that is your vent
2. The line goes to the cable tray and heads to the front, as it exits the front bulkhead it turns down and ends just above the angle that is the bottom of the bulkhead almost dead center.
Pamela & Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Diesel smell in basement

Reply #12 –
Thank you for that bit of information.  I went out, crawled underneath, and found it.  As you said, it comes down from the cableway and ends just above the big angle at the front bulkhead.  It is fastened so close it is almost jammed up against the angle.  And in that 1/8 inch of space between the end of the tubing and the bottom of the angle was a little gob of Alaska mud.
So if that vent line got clogged how does it vent?
BJ Holden
'98 U320 36'
Motorcade #16754

Re: Diesel smell in basement

Reply #13 –
Quote from: corndog254 –
of the angle was a little gob of Alaska mud.
So if that vent line got clogged how does it vent?
Mud daubbers also do a number on that line too.
 
If you don't have a venting fuel cap most likely out around that gasket of the fuel tap for the aquahot.

Pamela & Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Diesel smell in basement

Reply #14 –
BJ,

While clean take a piece of screen wire and make a cover for it and tie wrap it around the line. It will prevent future problems.

Pamela & Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."