Citroen Specials Club - the club for all lightweight cyclecars

Hello. Looking for some advice regarding petrol/exhaust fumes that appear mostly when I change gear or make large changes in throttle. I’m very new to the 2CV engine so any advice would be welcome. On searching the internet for advice I came across an article at hubnut.org that gave the following advice -

You learn as a 2CVer to smell the difference between head fumes and general exhaust fumes. I have one or two leaky clamps so I get that smell too! The cylinder head leak fumes are a bit sweeter. Less sharp. They typically occur when the engine is under high load, with a surge in aroma as you lift off the throttle. Exhaust fumes tend to be at their worse as the car is slowing or travelling downhill on a closed throttle, but in gear. There may also be a popping noise.

- This would suggest a cylinder head leak. The car is running well so I don’t want to start taking it to bits until I’m sure of the cause. Would a compression test eliminate the cylinder head leak? Any other ideas? Thanks in advance.

Hi Karic,

Not sure of what car you have and I assume it's an open top model. Firstly I'd take out the plugs and see if there is an indication of a rich mixture - that could indicate that the carb was flooding and needed looking at. Perhaps a float level problem.

Thanks billp. Sorry for the delay in replying but only just seen your message. I've made a few changes since my original message. New float bowl gasket, adjusted the float height, new petrol pipe between pump and carb and new plugs. This seemed to reduce the problem. I've also changed the location of the tail pipe from the back to the side just in front of the rear wheel and that seemed to make a huge difference. I still get the occasional smell when changing gear but I guess that might be inevitable with an open top car. I still have a slight leak from the carb float bowl so have just ordered a new valve so that might help as well as the car might be running a bit rich if the float bowl is flooding. Hopefully the new valve will stop the leak and help with the smell.

Karic
And are the carb. floats floating OK ?
I expect leaky 2cv floats are unusual, though, being plastic.
Davidm

And check the crankcase breather. fumes from the crankcase can be super smelly!
Howard