Definitive answer needed.

[lyons]

Over the years I have always been troubled with a fuel smell in DHC boot, so need the "definitive answer"

Tank is new and solid, hoses are all fuel compliant, so while winter is here I need to tackle this problem again.

Reading previous answers from eg Angus is seems that my new gaskets from SNG should be fitted dry after roughing up the mating sufaces of the tank pick-up and the fuel sender with PTFE on the bolt threads. Is this recommended.

Previously have used bue hylomar with correct length bolts that do not bottom out with new copper washers and new hose clips - it still smells.

P.S Not related to fuel level in tank.

Thanks

[politeperson]

Leaks form the sender and fuel supply panels on the top of the tank should be obvious with the boot floor removed, especially when the tank is full. They are actually positioned slightly below the highest point of the tank if you look.

If fuel is leaking anywhere from the tank, you should see droplets on the ground, at the left hand side of the car behind the wheel, or drops of fuel on the seam between the boot floor and the IRS cover panels.

The most common point for the tank to leak is the filler tube lower hose clip. It is difficult to seal with a single jubilee, sometimes it needs two. Sometimes the rubber filler tube is supplied the incorrect diameter to get a snug seal. Sometimes this joint can leak only when the car is being filled or under hard cornering as the fuel sloshed around, just smelling of fuel the rest of the time in the car as it vents.

Maybe your breather hose is venting into the car because it is split or detached form the fuel filler box at the top? The only way to tell is to slide the tank out and have a look.

Sliding the tank out can be a bit if a bear as you have to lean right in. 2 out of 3 bolts need a wobble on your socket to extract them. One of the tank support brackets needs removing for the outside in the center of the car near the IRS which can be a bit tight, use a ratchet spanner for the 4 short half inch set screws. Also the LH inner wing strengthening panel can sometimes be set at a slightly lower height than the top of the tank, meaning some gentle massaging may be required to lift it over the tank as it slides into the center of the car.

If you have a later US car, it also has additional vent tubes from the tank to the carbon canister which could be a vent point inside the car if they split.

[lyons]

Thanks for your reply.

I have already gone to the pain of extracting the NEW tank again just to make sure that all the hoses were connected. After this, filled the tank 1/2 full and went for a run and the fuel smell filled the cabin.

It is spoiling was is really a good car which drives well, but no distance can be covered comfortably, hence back to the gaskets on the top of the tank - dry or sealed that is the question.

Has anyone installed these gaskets successfully without any sealing medium between ? or used a good fuel compliant sealer.

Thanks

P.S Will try double clips on the main filling hose just to see it it helps

[rswaffie]

Hi,
I don’t know what model you have, but I had something similar on my 3.8 fhc. I started getting fuel smells in the cabin and after ruling out leaking carbs etc under the bonnet, I checked the pump and sender gaskets but all were ok. What I found was the banjo union (28 below) holding the nylon fuel pipe where it goes through the rear boot bulkhead was not tight and fuel had been dripping down behind the spare wheel and also soaked into the cloth I had wrapped around the spinner mallet that was tucked below the union. When I tightened it, problem solved.

[vee12eman]

Hi.
I had similar problems and also read about the Angus’ ideas of dry joint with roughing prior to assembling. I have recently replaced the gasket as described and like you had previously used hylomar. That had softened and escaped from the joint in a soft stringy mess, despite careful application originally. I also remember the original gasket sliding out of the joint on assembly, even before the screws were tight. That didn’t happen with the dry/rough assembly. I did not use PTFE. I was sick of the smell (FHC) and my wife was reluctant to get in the car with the smell, so I added a belt/braces approach of some fuel resistant sealant over the screws and covering both that and the joint with aluminium tape (self adhesive). I have little concern for absolute original appearance and the smell has gone. Difficult to say if it is the gasket or the tape doing the trick but it seemed much better on assembly, prior to adding the aluminium tape and Angus definitely knows his stuff. Dry/roughed is the way to go in my opinion.

Good luck.

[JerryL770]

You don't say what model or vintage you have but from your comments I presume it is a S1 or S2 FHC. If it is S3 I do not know if the following still applies.

When I got my FHC after restoration I had fuel smell lots of the time, irrespective of fuel level. I had no leaks anywhere. The problem was the wrong filler cap on the tank. I needed the one with a vent hole. Changing the cap to one with a vent hole cured the problem completely.

If you do not have a vented cap, either swap for one or simply drill a 1.6mm hole through the top of the cap near the centre.

[lowact]

DHC, you mean OTS? If so yr problem is almost certainly exhaust fumes.

E-types without or with modified emissions control generally run rich, there are unburnt hydrocarbons in the exhaust from which, due to e-type aerodynamics, you can never escape. Result can be hair, clothes, luggage smelling of petrol. May be most noticeable after lengthy journeys at highway speed, under such steady state conditions, due to the aerodynamics, cloud of exhaust is firmly anchored to and surrounding the rear of the car.

Fumes get into the boot via empty screw/bolt holes, drains without bungs and loose or worn boot lid seal. Largest opening is usually the gap between the ends of the boot lid seal at the latch.

Worst case is if there is opening from the bottom of the boot across which there is negative pressure, i.e. air is sucked out of the boot. This air is replaced by exhaust fumes through other openings, i.e. you have a positively powered circulation of exhaust gases through the boot.

This issue is pretty much confined to OTS cars. With FHC’s the “boot” is part of the cabin, there is positive ventilation drawn from the front of the car, at other openings there is cabin air exiting, not exhaust gases entering.

Posts on other forums suggest meticulously sealing the boot; difficult to do entirely. Another solution may be to implement a boot ventilation system that effectively mimics the FHC condition. Install a rear facing nozzle from one of the boot floor drains, for strong suction of air from the boot. Install a generous air supply to the boot, ducted from a location towards the front of the car where there is positive pressure and no exhaust contamination.

Solving the boot issue still leaves the hair and clothes. To solve this, first requirement is to get yr car professionally tuned using an exhaust gas analyser to reduce unburnt hydrocarbons. Again difficult to do entirely due to our cars are 60 year old technology. Next solution would be to have a catalytic converter retrofitted. Difficult, not a backyard or local mechanic job, would need to be designed, by cat experts.

[chrisfell]

I had fuel smells for ages. I replaced the gasket, sealed with all sorts of gunk, did that all again, and still after filling the tank fuel leaked all over the top. Then I placed some blue paper towels all over the top of the tank and went for a drive with a full tank, stoping regularly to see where the leak was coming from. It was the hose connection all the time. I bought a new clip, tightened it and have had no fuel smells since.

I get smells, mainly oil dripping on hot exhaust, but not fuel, and not from the tank.