gas smell in gtd drivers compartment

[vic mastrorocco]

I been asked for any sugestions regarding dealing with gas fumes in the drivers compartment of late model GTD 40. Has anybody had this problem ?

I occaisionally got fuel smells when both fuel tanks were very full ie to the brim. Run a bit off both sides and the whiff went!

Otherwise can only suggest you check all pipe connections and joints thoroughly.

Malcolm

[DC]

I've just cured a similar problem. I know you can get fuel smells from the standard fuel caps as they do not seal the tanks. I fitted locking Aero fillers inside the original caps (they are a dead size very fortunately) - these seal and I get no smells/leaks at the front. You do have to change the filler necks etc.

The rear is a different problem. I had several sources of leaks and the smell seemed to permeate back up the pontoons into the cabin, this happended when the tanks were full or after a burst of acceleration. In fact parking on my drive, which is sloped, with full-ish tanks caused a drip from the sills.

1) The bolts holding the fuel senders into the tank leaked up the threads, I used Chemical metal two pack (the only compound I found which specially states being fuel proof) to bond some threaded rod (bolts with the heads cut off) into the fixing holes - this seals them well, you then obviously use nuts to make the fixing.

2) My fuel senders leaked under the flange and I made up some rubber gaskets to go under them.

3) Lastly I had fitted some tank breather valves at the rear of the tanks. I did this at the back as some one said you can get air expansion in hot weather which forces fuel up the filler hose and potentially out. They allow air in as fuel is used (which is important if you seal the front of the tank with proper filler caps) AND are supposed to prevent fuel escape from splashing in the tank (or roll over - God forbid!). However I found they do leak if the tank is full-ish - maybe faulty? I temporarily removed the nearside and hey presto no fuel smells or leaks even with a full tank at all now.

I do still need to vent the tank as when you open the filler after a run there is a long loud sucking noise of air entering. I will probably run a line from the vent to the top of the front filler and vent it there.

Hope this helps.

[pete vines]

The problem I had was that the breather on the front was well below the top of the tank. When the tank was full there was a lot of air trapped. As the car moved, or the temperature went up, pressure was built up in the system which tended to force the fuel back up the filler tube. This forced the fumes out into the cabin. I added a breather right in the middle of the top. There isn't a lot of room but it cured the problem.

[Brian Magee]

I sometimes get a smell of gas in my car - normaly just after I have frightened myself! [img]images/icons/grin.gif[/img] [img]images/icons/grin.gif[/img]

Brian.

[Howard Jones]

Dave I'm worried about liquid fuel dripping from your sidepods ANYTIME. Please find the leak and fix it. This could turn into a very bad day in the GT40 world. My smelly gas problem came from a sloppy job of filling the fuel tanks and getting a little fuel on the filler plate. Just about any will cause a fuel smell in the cockpit. I have decided to add a roll over check valve in each filler plate vent line. I was looking a a friends sprint car and I believe that a 1/2" check valve in the vent line would do the trick. I will have to weld a proper fillneck on to the original plate, under the current flip up cap, thus allowing for a proper non venting cap. The vent line must be routed to a different place on the fill plate to provide atmospheric pressure to the tank.In the event of a rollover the fuel will be contained in the tank via the sealing fuel cap and a now closed rollover valve. This is the way my friends sprint car is setup. All this stuff can be sourced from www.racerpartswholesale.com 1-800-379-7815.
Any body got any good ideas in this area?

Another idea is to change the tank breather connection position from the front of the tank to the rear so that it gets less fuel in it as you fill up. Maybe best to do that mod when there is zero fuel (and zero fuel fumes)! [img]images/icons/grin.gif[/img]

Malcolm

[Dave Bilyk]

I have fixed one fuel leak, which was due to a leaking diaphragm in the fuel pressure regulator.
Although my car is a DAX the problem seems to be similar to the ones in this thread. Now I find that the drivers side fuel sender appears to be designed to vent the tank since it has a pressed rim with a hole drilled in the sealing ridge. Since it is on a thin paper gasket, this hole is not sealed by the gasket.
The sender also has a larger vent union. The hose connected to this union comes back then loops forward into the sill area. I think it is probably connected to the filler overfill drain, but have yet to check thoroughly.
If I seal the small hole in the sender unit, I dont think that the tank will be vented at all, since the filler drain is in the area sealed by the spring loaded cap.
So I think that I will need to provide an atmospheric vent with a check valve.
Any advice on the right way to do this appreciated.

regards
Dave

[Pete.]

[ QUOTE ]
I sometimes get a smell of gas in my car - normaly just after I have frightened myself! [image]

[/ QUOTE ]
Stop eating all those Vindaloo's [img]/ubbthreads/images/graemlins/grin.gif[/img]