whats the best (proper) way to put a hole in the firewall to run wires? drill, paint, grommet? how can i seal it?

is there a way to pull wires through the existing wiring harness hole?

ive never attempted this, so good seasoned help will be awesome
thanks

 

Depending upon what I'm doing, I usually just stick it out the engine harness gromet side, just by poking a hole in it and sticking my wire through, if it's required on the drivers side area, I usually find a path already made to go through, otherwise, as you said, drill, paint so it doesn't rust, jam a grommet in.

 

I've put a couple of wires through existing grommets as Rat as done, and the tube for my vac gauge had to have a drilled hole on the right side. RTV works very well as a "grommet" after running the wiring, to seal any holes you may drill, and to protect the wire/tube/etc from chaffing...

 

Good point, I usually run a ton of wires through at one time so I make a big one big enough for a grommet, didn't even think of RTV for tinier holes for single wires/etc. Good info!