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Hi all

I've noticed petrol dripping from underneath the manifold on my Lomax (2cv) engine. I first noticed it after running, but it also seems to happen when just pumping the pedal with the engine off. Now, I've read on this forum some other people discussing this, and understand that it can indicate a flooding carb (eg needle valve not sealing fully). But there was also mention that this can be "normal", and some later models had a pad to absorb the drips and allow it to evaporate.

So, before I think about poking about inside the carb, how much is "normal"? And are there any other tests to try or things to consider?

Thanks for any tips!

Andy

Hello MM.
There is a small pin hole on the bottom of the manifold directly below carb. Surplus fuel leaving the carb will run down and find the hole. Pumping the pedal will squirt fuel from the acceleration pump straight down into the mmanifold.
As far as I am aware, fuel dripping from this hole is normal on shutdown.....

Rob Bryant

Thanks Rob, that's very interesting. So the pumping situation makes sense, and isn't a problem. I guess the issue would be if it drips during normal running, not just at shutdown?

My fear is that it's a fire risk, of course -- although I suppose a Lomax (and even a 2CV) is "open" enough that vapour build-up in the engine bay isn't possible.

Hello again MM.
I often thought of the fire risk, but as you say, it evaporates away quickly on a clean visible engine block.
I always leave it idling for a minute before turning off, not sure if I am just convincing myself, but I think it helps reduce any dripping..
Rob Bryant

Rob,
I'd doubt that letting the engine idle prior to switching if off will make any difference, since the mechanical pump is actually more efficient in transferring fuel at low rpm.

As for Andy's original question,
Now, I've read on this forum some other people discussing this, and understand that it can indicate a flooding carb (eg needle valve not sealing fully). But there was also mention that this can be "normal", and some later models had a pad to absorb the drips and allow it to evaporate.
.
Leakage after shutdown can indeed suggest that the needle valve is not 100%, however if the engine ticks over reliably for several minutes, it's not (yet) a problem.
When it comes to the foam pad wedged between the manifold and the crankcase, that was fitted at the factory purely for transport purposes and should have been removed during the dealer's PDI...