Full rebuild - Stink of Petrol

[NYK]

Reached a major milestone in the 5 year full rebuild this week with the initial fire up of the engine which went well.
Tank was filled with around a gallon of fuel and pretty soon I noticed a strong smell of fuel. There was an obvious leak from the tank banjo so the tank was drained and I’m awaiting delivery of some fibre washers.
Two days after this trial there is still a stink of fuel, garage has been well ventilated. I have cut away any felt in the boot which probably soaked up some fuel and there is still a residual smell of fuel in the boot. However there also seems a really strong smell of fuel in the engine bay. There are no obvious signs of any leaks, everything seems dry. One carb has its pancake filter in place the other does not. I can see that there is fuel in the pump’s glass bowl and I presume the float chambers are still full of fuel.
Would one expect there to be a fuel smell in the engine bay under these circumstances?

[nmauduit]

if everything is tight and leak free there should be no strong smell on a 2 seater (not from the mechanical pump bowl, nor the carbs cuves) - only a normal "car smell" , which most people find very pleasant on the forum. If you have changed the fuel hoses, you may want to double check if they keep alcohol or let it perspire (though that should not make for a strong smell).

as for the rear, on Plus2 I've read that the fuel tank venting system is specific (including hoses going around the rear screen), which may be an other lead for things to double check in addition to the items you've already listed.

Then of course the most obvious : if the tank is original, pinholes due to corrosion from inside (water ingress or condensation) can be a nuisance and should be treated...

good luck !

[NYK]

During the rebuild I did the Plus 2 tank vent mod, aside from the tank everything is new or rebuilt. I’m more curious about the petrol smell in the engine bay, I suspect the smell in the boot is due to the initial leak.

[ericbushby]

Weber carburettors always lose petrol by evaporation after use. This is more severe with a hot engine though. If you do not have Webers, then please ignore the above.
Eric in Burnley
S3 DHC

[NYK]

Weber carburettors always lose petrol by evaporation after use. This is more severe with a hot engine though. If you do not have Webers, then please ignore the above.
Eric in Burnley
S3 DHC

Sorry, I should have mentioned they are Dellortos

[davidj]

If the accelerator pump diaphragm on dellortos is leaking, petrol will drip onto the distributor and starter. Always wise to check.

[NYK]

If the accelerator pump diaphragm on dellortos is leaking, petrol will drip onto the distributor and starter. Always wise to check.

I replaced diaphragms when I stripped the carbs, I also crawled under the car today there are no signs of leaks anywhere. The engine is fully rebuilt and the engine bay is fresh paintwork so it’s really easy to see if there were drips or moist pipes etc. I really could see nothing. Very odd, perhaps petrol spills just take a long time to dissipate.

[Bigbaldybloke]

Regarding the tank banjo fitting, mine always seemed just damp on the outside, never dripping but damp. I tried it with copper washers, fibre washers and aluminium washers, no change. I machined the underside of the bolt head on my lathe to ensure it was flat and square, still the same. Eventually found that the banjo was the wrong size, the hole the pipe went into was oversize and allowed the pipe to skew and the olive wasn’t sealing properly. Found a different banjo which was a snug fit on the pipe and all sorted. As it’s an alloy tank I used aluminium washers. All fine now, completely dry.

[nmauduit]

All fine now, completely dry.

Glad to know all is well now, adequate metal banjo seal should be strong, safe and long lasting (fiber need to be of proper quality to stand fuel over time, I would prefer not to use them hiden in the trunk).

[alan.barker]

Just for info the position of the "Olive" on the Fuel line should not be flush with the end of the Fuel Line.
It should be a little back along the Fuel line. Then when assembled the Fuel line will locate (centralise) in the Banjo keeping it square. The end of the Fuel Line must slide into the hole in the Banjo before nipping up the Olive.
It's best to nip up/set the Olive before Banjo is placed upto the Fuel Tank.
Access for assembly to Fuel Tank is very difficult and a one Hand job.
Alan

[Bigbaldybloke]

Hi Alan, you’re right the banjo is a pain to get to, that explains why I had not noticed that the pipe was a loose fit in the banjo earlier. I’m well used to making up compression fittings having been an instrument technician working on offshore oil rigs in a previous life where we had gauges to check the position of the rings on pipe joints we made up. I found that the best way to access the banjo was from the left side wheel arch as I’m right handed.
For info we occasionally used to test our joints to failure and with a properly made up joint the pipe would usually fail before the joint at around 15,000psi, that’s with stainless tubing and double ring fittings!

[alan.barker]

Hi Bigbaldybloke,
sorry if it seemed i was telling you how to suck Eggs. With the plastic Fuel Line it's not easy and gets necked easily when Olive is nipped up.
Oh the joys of Lotus
Alan