Please help, rear carb is dumping fuel from this spot where the blue arrow is.
What is this, what is supposed to be here (it does not look threaded underneath) and can I plug it or seal it with RTV?




Thanks.

RTV won't hold up to fuel. Go to the vintage portion of this board, some over there have dealt with these carbs.

I know carbs in general, but I don't have direct experience with these Zenith units, and I'm going off a photo that doesn't show much detail, so take this with a grain of salt:

It's hard to tell exactly but it looks like you are pointing at the area where the "Bowl Vent Valve" is located. Part of the throttle lever extends under there, and operates the valve (holds open at idle?). Fuel coming out there would seem to indicate trouble with the needle valve and/or float assembly, i.e. fuel free flowing through the bowl and out the vent. Does the car run rich? You might pull one of those rear spark plugs and compare to one of the fronts.

I'd read up on those Zenith INAT carbs. I searched "zenith inat carb" and got a lot of hits. Might be time to go through both of them, clean everything up and replace all the consumable parts with fresh ones from a kit, and check/set all the adjustments. At minimum you'd be looking at pulling the top off that carb to have a look.

I could be wrong about all this. Maybe a better photo of the area that's getting wet, while it's wet?

__________________
- Greg -
1973 220D, The Prodigal Benz
1974 240D