Having a stack without a flapper

[Chevysilver0195]

Just bought a diesel has a stack on it. The guys helping me work on it said it isn't good to have a stack without a flapper cause the rain goes down it what do you guys think

[trbankii]

Well, I’m refrain from comments on stacks on pickups… But you’re obviously going to get rain in there. Depending on how regularly you drive it and how far you typically go, it is either going to accumulate and be a nuisance or just vaporize.

[Dvldog8793]

Howdy
Water will accumulate in the lowest part of the system and might eventually rust it out. It might also blow a big bunch of nastiness out when you fire it up, so make sure you park next to the appropriate person.
The main thing farmer flappers were for is to keep rain out of tractors that had a direct shot to the engine. In some of those the rain could go straight into the engine from the pipe....we always used a coffee can:D

Hope this helps!