There is an ugly part in my old Dodge b250 campervan somebody has helpfully held in place with an coathanger. It consists of a duct (with torn sections) from the manifold up to the intake of the air filter, and rusty remains of a housing that I think used to cover the entire manifold. I'd like to replace it either with a matching part, or maybe just remove it entirely, since it definitely isn't working as intended right now.

From what I understand it is intended to pull in hot air from around the manifold for emissions purposes.

Not exactly sure what to call it, I've tried "heated air inlet duct" and similar terms., but haven't found the part, discontinued or otherwise.

full view, from passenger side coathanger fix

Do I need this part?

2 Answers 2


It was not for emissions purposes, it was for the cold weather when the air was very cold and the venturi effect in the carb would cause the moisture to freeze causing running problems.

Finding a replacement would be a good idea, or making something neat to do the same.

  • Hot air will decrease power due to a lower air density, is this a constant hot air feed or only if the temperature drops below a certain level.
    – GdD
    Commented Jul 3, 2019 at 15:13
  • @GdD if you look above the pipe bringing the hot air (top image), there is a vacuum controlled round bit which senses the temperature and moves a flap to choose either warmer or colder air as appropriate... It was, as I said, for the colder weather.
    – Solar Mike
    Commented Jul 3, 2019 at 15:16
  • thanks solarmike. it's a camper, 90% driving is summer, so sounds like this intake won't even be used until we do some winter trips. I am going to remove it for now and see about tracking down a replacement Commented Jul 3, 2019 at 17:16

You can find a replacement for the corrugated tubing at just about any auto parts stove. Some car makers called it a stove heater tube. When you start the engine in cold weather, the diverter valve in the snorkel closes off cold air from the open end of the snorkel and sucks air that's been warmed by the exhaust manifold. That's to prevent carburetor icing and to help fuel vaporization in cold weather. Once the engine heats up, the diverter closes off the hot air and sucks air through the open end. Getting this back in working order will help with cold weather operation.

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